Question: what are the transmission routes of coronavirus?

Title: Is SARS-CoV-2 Also an Enteric Pathogen With Potential Fecal-Oral Transmission? A COVID-19 Virological and Clinical Review Content: In as few as 3 months, coronavirus disease 2019 (COVID-19) has spread and ravaged the world at an unprecedented speed in modern history, rivaling the 1918 flu pandemic. Severe acute respiratory syndrome coronavirus-2, the culprit virus, is highly contagious and stable in the environment and transmits predominantly among humans via the respiratory route. Accumulating evidence suggest that this virus, like many of its related viruses, may also be an enteric virus that can spread via the fecal-oral route. Such a hypothesis would also contribute to the rapidity and proliferation of this pandemic. Here we briefly summarize what is known about this family of viruses and literature basis of the hypothesis that severe acute respiratory syndrome coronavirus-2 is capable of infecting the gastrointestinal tract and shedding in the environment for potential human-to-human transmission.

Title: Closing the knowledge gaps on MERS: three and half years since its detection, what have we learnt and what needs to be done urgently? (Editorial). Content: The Middle East respiratory syndrome coronavirus (MERS-Cov), first detected in 2012, continues to cause health concerns owing to the grave uncertainties that have surrounded the virus since it emerged. Three and half years after the first known human infection was detected, cases continue to be reported every month, over 85% of which have been from Saudi Arabia and other countries in the Arabian Peninsula. Despite its low levels of transmission, the virus presents an uncertain future as a number of critical knowledge gaps on the source and route of transmission have hindered the global response to this emerging infection.

Title: Facing the COVID‐19 outbreak: What should we know and what could we do? Content: A novel coronavirus, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), emerged in Wuhan, Hubei Province in China in December 2019 and caused a serious type of pneumonia called coronavirus disease 2019 or COVID-19. This epidemic quickly spread across China and extended to more than 20 other countries. This commentary discusses the reasons for the fast spread of SARS-CoV-2 in three aspects: the infectious sources, including the biological nature of the virus; the susceptible population; and the transmission routes. The current situations and suggestions regarding the control of the disease are summarized. This article is protected by copyright. All rights reserved.

Title: Tissue Distribution of the MERS-Coronavirus Receptor in Bats Content: Middle East respiratory syndrome coronavirus (MERS-CoV) has been shown to infect both humans and dromedary camels using dipeptidyl peptidase-4 (DPP4) as its receptor. The distribution of DPP4 in the respiratory tract tissues of humans and camels reflects MERS-CoV tropism. Apart from dromedary camels, insectivorous bats are suggested as another natural reservoir for MERS-like-CoVs. In order to gain insight on the tropism of these viruses in bats, we studied the DPP4 distribution in the respiratory and extra-respiratory tissues of two frugivorous bat species (Epomophorus gambianus and Rousettus aegyptiacus) and two insectivorous bat species (Pipistrellus pipistrellus and Eptesicus serotinus). In the frugivorous bats, DPP4 was present in epithelial cells of both the respiratory and the intestinal tract, similar to what has been reported for camels and humans. In the insectivorous bats, however, DPP4 expression in epithelial cells of the respiratory tract was almost absent. The preferential expression of DPP4 in the intestinal tract of insectivorous bats, suggests that transmission of MERS-like-CoVs mainly occurs via the fecal-oral route. Our results highlight differences in the distribution of DPP4 expression among MERS-CoV susceptible species, which might influence variability in virus tropism, pathogenesis and transmission route.

Title: [Transmission routes of 2019-novel coronavirus (2019-nCoV)] Content: Since the outbreak of COVID-19 in Wuhan, China, at the end of 2019, it has demonstrated China's ability to identify unknown pathogens. At present, reports showed that the main transmission routes are respiratory droplets and indirect contact, other vertical transmission routes have yet to be confirmed. This review discusses the possible transmission routes of 2019-novel coronavirus (2019-nCoV), based on currently research, the main transmission routes are respiratory droplets and indirect contact, fecal-oral might bepossible, while aerosol, tear (conjunctival) and mother-to-fetus still have yet to be confirmed, providing a reference basis for 2019-nCoV prevention and control and public protection.

Title: [Transmission routes of 2019-novel coronavirus (2019-nCoV)]. Content: Since the outbreak of COVID-19 in Wuhan, China, at the end of 2019, it has demonstrated China's ability to identify unknown pathogens. At present, reports showed that the main transmission routes are respiratory droplets and indirect contact, other vertical transmission routes have yet to be confirmed. This review discusses the possible transmission routes of 2019-novel coronavirus (2019-nCoV), based on currently research, the main transmission routes are respiratory droplets and indirect contact, fecal-oral might bepossible, while aerosol, tear (conjunctival) and mother-to-fetus still have yet to be confirmed, providing a reference basis for 2019-nCoV prevention and control and public protection.

Title: Is SARS-CoV-2 Also an Enteric Pathogen with Potential Fecal-Oral Transmission: A COVID-19 Virological and Clinical Review Content: Abstract In as short as 3 months, COVID-19 has spread and ravaged the world in an unprecedented speed in modern history rivaling the 1918 flu pandemic. SARS-CoV-2, the culprit virus, is highly contagious and stable in the environment and predominantly transmits among humans via the respiratory route. Accumulating evidence suggest that this virus, like many of its related viruses, may also be an enteric virus that can spread via the fecal-oral route. Such a hypothesis would also contribute to the rapidity and proliferation of this pandemic. Here we briefly summarize what is known about this family of viruses and literature basis of the hypothesis that SARS-CoV-2 is capable of infecting the gastrointestinal tract and shedding in the environment for potential human-to-human transmission.

Title: Personal Protective Equipment and COVID-19: A Review for Surgeons Content: There is a long history of personal protective equipment (PPE) used by the surgeon to minimize the transmission of various pathogens. In the context of the present coronavirus disease 2019 pandemic there is significant controversy as to what forms of PPE are appropriate or adequate. This review aims to describe the pathogenic mechanism and route of spread of the causative virus, severe acute respiratory syndrome coronavirus, as it pertains to accumulated published data from experienced centers globally. The various forms of PPE that are both available and appropriate are addressed. There are options in the form of eyewear, gloves, masks, respirators, and gowns. The logical and practical utilization of these should be data driven and evolve based on both experience and data. Last, situations specific to surgical populations are addressed. We aim to provide granular collective data that has thus far been published and that can be used as a reference for optimal PPE choices in the perioperative setting for surgical teams.

Title: Personal Protective Equipment and COVID-19: A Review for Surgeons Content: : There is a long history of personal protective equipment (PPE) used by the surgeon to minimize the transmission of various pathogens. In the context of the present coronavirus disease 2019 pandemic there is significant controversy as to what forms of PPE are appropriate or adequate. This review aims to describe the pathogenic mechanism and route of spread of the causative virus, severe acute respiratory syndrome coronavirus, as it pertains to accumulated published data from experienced centers globally. The various forms of PPE that are both available and appropriate are addressed. There are options in the form of eyewear, gloves, masks, respirators, and gowns. The logical and practical utilization of these should be data driven and evolve based on both experience and data. Last, situations specific to surgical populations are addressed. We aim to provide granular collective data that has thus far been published and that can be used as a reference for optimal PPE choices in the perioperative setting for surgical teams.

Title: Role of fomites in SARS transmission during the largest hospital outbreak in Hong Kong Content: The epidemic of severe acute respiratory syndrome (SARS) had a significant effect on global society in the early 2000s and the potential of its resurgence exists. Studies on the modes of transmission of SARS are limited though a number of outbreak studies have revealed the possible airborne route. To develop more specific and effective control strategies, we conducted a detailed mechanism-based investigation that explored the role of fomite transmission in the well-known Ward 8A outbreak. We considered three hypothetical transmission routes, i.e., the long-range airborne, fomite and combined routes, in 1,744 scenarios with combinations of some important parameters. A multi-agent model was used to predict the infection risk distributions of the three hypothetical routes. Model selection was carried out for different scenarios to compare the distributions of infection risk with that of the reported attack rates and select the hypotheses with the best fitness. Our results reveal that under the assumed conditions, the SARS coronavirus was most possible to have spread via the combined long-range airborne and fomite routes, and that the fomite route played a non-negligible role in the transmission.

Title: A study of the probable transmission routes of MERS‐CoV during the first hospital outbreak in the Republic of Korea Content: Infections caused by the Middle East respiratory syndrome coronavirus (MERS‐CoV) are a serious health issue due to their prevalence and associated mortality. However, the transmission routes of the virus remain unclear, and thus, the current recommended control strategies are not evidence based. In this study, we investigated the transmission routes of MERS‐CoV during the first nosocomial outbreak in the Republic of Korea in May 2015 using a multi‐agent modeling framework. We identified seven hypothesized transmission modes based on the three main transmission routes (long‐range airborne, close contact, and fomite). The infection risks for each hypothesis were estimated using the multi‐agent modeling framework. Least‐squares fitting was conducted to compare the distribution of the predicted infection risk in the various scenarios with that of the reported attack rates and to identify the hypotheses with the best fit. In the scenarios in which the index patient was a super‐spreader, our model simulations suggested that MERS‐CoV probably spread via the long‐range airborne route. However, it is possible that the index patient shed an average viral load comparable to the loads reported in the literature, and that transmission occurred via a combined long‐range airborne and close contact route.

Title: Transmission routes of 2019-nCoV and controls in dental practice Content: A novel β-coronavirus (2019-nCoV) caused severe and even fetal pneumonia explored in a seafood market of Wuhan city, Hubei province, China, and rapidly spread to other provinces of China and other countries. The 2019-nCoV was different from SARS-CoV, but shared the same host receptor the human angiotensin-converting enzyme 2 (ACE2). The natural host of 2019-nCoV may be the bat Rhinolophus affinis as 2019-nCoV showed 96.2% of whole-genome identity to BatCoV RaTG13. The person-to-person transmission routes of 2019-nCoV included direct transmission, such as cough, sneeze, droplet inhalation transmission, and contact transmission, such as the contact with oral, nasal, and eye mucous membranes. 2019-nCoV can also be transmitted through the saliva, and the fetal–oral routes may also be a potential person-to-person transmission route. The participants in dental practice expose to tremendous risk of 2019-nCoV infection due to the face-to-face communication and the exposure to saliva, blood, and other body fluids, and the handling of sharp instruments. Dental professionals play great roles in preventing the transmission of 2019-nCoV. Here we recommend the infection control measures during dental practice to block the person-to-person transmission routes in dental clinics and hospitals.

Title: Transmission routes of 2019-nCoV and controls in dental practice Content: A novel ß-coronavirus (2019-nCoV) caused severe and even fetal pneumonia explored in a seafood market of Wuhan city, Hubei province, China, and rapidly spread to other provinces of China and other countries. The 2019-nCoV was different from SARS-CoV, but shared the same host receptor the human angiotensin-converting enzyme 2 (ACE2). The natural host of 2019-nCoV may be the bat Rhinolophus affinis as 2019-nCoV showed 96.2% of whole-genome identity to BatCoV RaTG13. The person-to-person transmission routes of 2019-nCoV included direct transmission, such as cough, sneeze, droplet inhalation transmission, and contact transmission, such as the contact with oral, nasal, and eye mucous membranes. 2019-nCoV can also be transmitted through the saliva, and the fetal-oral routes may also be a potential person-to-person transmission route. The participants in dental practice expose to tremendous risk of 2019-nCoV infection due to the face-to-face communication and the exposure to saliva, blood, and other body fluids, and the handling of sharp instruments. Dental professionals play great roles in preventing the transmission of 2019-nCoV. Here we recommend the infection control measures during dental practice to block the person-to-person transmission routes in dental clinics and hospitals.

Title: Routes of transmission of influenza A H1N1, SARS CoV, and norovirus in air cabin: Comparative analyses Content: Identifying the exact transmission route(s) of infectious diseases in indoor environments is a crucial step in developing effective intervention strategies. In this study, we proposed a comparative analysis approach and built a model to simulate outbreaks of 3 different in‐flight infections in a similar cabin environment, that is, influenza A H1N1, severe acute respiratory syndrome (SARS) coronavirus (CoV), and norovirus. The simulation results seemed to suggest that the close contact route was probably the most significant route (contributes 70%, 95% confidence interval [CI]: 67%‐72%) in the in‐flight transmission of influenza A H1N1 transmission; as a result, passengers within 2 rows of the index case had a significantly higher infection risk than others in the outbreak (relative risk [RR]: 13.4, 95% CI: 1.5‐121.2, P = .019). For SARS CoV, the airborne, close contact, and fomite routes contributed 21% (95% CI: 19%‐23%), 29% (95% CI: 27%‐31%), and 50% (95% CI: 48%‐53%), respectively. For norovirus, the simulation results suggested that the fomite route played the dominant role (contributes 85%, 95% CI: 83%‐87%) in most cases; as a result, passengers in aisle seats had a significantly higher infection risk than others (RR: 9.5, 95% CI: 1.2‐77.4, P = .022). This work highlighted a method for using observed outbreak data to analyze the roles of different infection transmission routes.

Title: What was the primary mode of smallpox transmission? Implications for biodefense Content: The mode of infection transmission has profound implications for effective containment by public health interventions. The mode of smallpox transmission was never conclusively established. Although, “respiratory droplet” transmission was generally regarded as the primary mode of transmission, the relative importance of large ballistic droplets and fine particle aerosols that remain suspended in air for more than a few seconds was never resolved. This review examines evidence from the history of variolation, data on mucosal infection collected in the last decades of smallpox transmission, aerosol measurements, animal models, reports of smallpox lung among healthcare workers, and the epidemiology of smallpox regarding the potential importance of fine particle aerosol mediated transmission. I introduce briefly the term anisotropic infection to describe the behavior of Variola major in which route of infection appears to have altered the severity of disease.

Title: COVID-19 pandemic: Impact of lockdown, contact and non-contact transmissions on infection dynamics Content: COVID-19 coronavirus pandemic has virtually locked down the entire world of human population, and through its rapid and unstoppable spread COVID-19 has essentially compartmentalised the population merely into susceptible, exposed, infected and recovered classes. Adapting the classical epidemic modelling framework, two distinct routes of COVID-19 transmission are incorporated into a model: (a) direct person-to-person contact transmission, and (b) indirect airborne and fomites-driven transmission. The indirect non-contact transmission route needs to explored in models of COVID-19 spread, because evidences show that this route of transmission is entirely viable with hugely uncertain level of relative contribution. This theoretical study based on model simulations demonstrates the following: (1) Not incorporating indirect transmission route in the model leads to underestimation of the basic reproduction number, and hence will impact on the COVID-19 mitigation decisions; (2) Lockdown measures can suppress the primary infection peak, but will lead to a secondary peak whose relative strength and time of occurrence depend on the success and duration of the lockdown measures; (3) To make lockdown effective, a considerable level of reduction in both contact and non-contact transmission rates over a long period is required; (4) To bring down the infection cases below any hypothetical health-care capacity, reduction of non-contact transmission rate is key, and hence active measures should be taken to reduce non-contact transmission (e.g., extensive uses of areal and aerosol disinfectant in public spaces to improve contaminated surfaces and air); (5) Any premature withdrawal of lockdown following the sign of a brief retracement in the infection cases can backfire, and can lead to a quicker, sharper and higher secondary peak, due to reactivation of the two transmission routes. Based on these results, this study recommends that any exit policy from lockdown, should take into account the level of transmission reduction in both routes, the absolute scale of which will vary among countries depending on their health-service capacity, but should be computed using accurate time-series data on infection cases and transmission rates.

Title: Body fluids may contribute to human-to-human transmission of severe acute respiratory syndrome coronavirus 2: evidence and practical experience Content: BACKGROUND: In December 2019, an unbelievable outbreak of pneumonia associated with coronavirus was reported in the city of Wuhan, Hubei Province. This virus was called severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Although much effort has been spent on clarifying the transmission route of SARS-CoV-2, but, very little evidence is available regarding the relationship between human body fluids and transmission of SARS-CoV-2 virus. Considerable evidence from hospital in Wuhan indicates that strict rules to avoid occupational exposure to patients’ body fluids in healthcare settings, particularly among every medical staff, limited person-to-person transmission of nosocomial infections by direct or indirect contact. CONCLUSION: We tried to provide important information for understanding the possible transmission routes of SARS-CoV-2 via body fluids including bronchoalveolar-lavage, saliva, blood, urine, feces, sputum, tears, and semen in order to control coronavirus disease 2019 (COVID-19) occurrences.

Title: Transmission routes of SARS-CoV-2 and protective measures in dental clinics during the COVID-19 pandemic Content: RESULTS: The outbreak of coronavirus disease 2019 (COVID-19) has become a primary challenging public health issue for not only China but also the world On March 11, 2020, the World Health Organization declared that the pandemic of COVID-19 had become a public health emergency of global concern As of May 12, 2020 COVID-19 has been reported in over 180 countries/regions, with a total of 4,178,156 confirmed cases and over 280,000 deaths The risk of cross-infection by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) might be elevated between dental specialists and patients due to the peculiarity of dental practice Therefore, detailed and effective infection control measures are imminently needed to prevent nosocomial coronavirus infection This paper, based on proven effective experience, relevant guidelines, and research, not only presents the fundamental knowledge about the name, etiologic characteristics, epidemiologic characteristics and clinical manifestations of COVID-19, transmission routes and risk points of SARS-CoV-2 in dental clinics but also provides recommended protective measures for dental professionals to interdict the transmission of SARS-CoV-2 in dental clinics Classification schemes as well as color identification according to the results of the questionnaire survey and temperature measurement in precheck and triages are innovations proposed in this paper CLINICAL SIGNIFICANCE: This paper, based on proven effective experience, relevant guidelines, and research, not only presents the fundamental knowledge about the name, etiologic characteristics, epidemiologic characteristics and clinical manifestations of COVID-19, transmission routes and risk points of SARS-CoV-2 in dental clinics but also provides recommended protective measures for dental professionals to interdict the transmission of SARS-CoV-2 in dental clinics

Title: Transmission routes of SARS-CoV-2 and protective measures in dental clinics during the COVID-19 pandemic. Content: RESULTS The outbreak of coronavirus disease 2019 (COVID-19) has become a primary challenging public health issue for not only China but also the world. On March 11, 2020, the World Health Organization declared that the pandemic of COVID-19 had become a public health emergency of global concern. As of May 12, 2020 COVID-19 has been reported in over 180 countries/regions, with a total of 4,178,156 confirmed cases and over 280,000 deaths. The risk of cross-infection by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) might be elevated between dental specialists and patients due to the peculiarity of dental practice. Therefore, detailed and effective infection control measures are imminently needed to prevent nosocomial coronavirus infection. This paper, based on proven effective experience, relevant guidelines, and research, not only presents the fundamental knowledge about the name, etiologic characteristics, epidemiologic characteristics and clinical manifestations of COVID-19, transmission routes and risk points of SARS-CoV-2 in dental clinics but also provides recommended protective measures for dental professionals to interdict the transmission of SARS-CoV-2 in dental clinics. Classification schemes as well as color identification according to the results of the questionnaire survey and temperature measurement in precheck and triages are innovations proposed in this paper. CLINICAL SIGNIFICANCE This paper, based on proven effective experience, relevant guidelines, and research, not only presents the fundamental knowledge about the name, etiologic characteristics, epidemiologic characteristics and clinical manifestations of COVID-19, transmission routes and risk points of SARS-CoV-2 in dental clinics but also provides recommended protective measures for dental professionals to interdict the transmission of SARS-CoV-2 in dental clinics.

Title: Controversy around airborne versus droplet transmission of respiratory viruses: implication for infection prevention. Content: PURPOSE OF REVIEW Health agencies recommend transmission-based precautions, including contact, droplet and airborne precautions, to mitigate transmission of respiratory viruses in healthcare settings. There is particular controversy over the importance of aerosol transmission and whether airborne precautions should be recommended for some respiratory viruses. Here, we review the current recommendations of transmission-based precautions and the latest evidence on the aerosol transmission of respiratory viruses. RECENT FINDINGS Viral nucleic acids, and in some instances viable viruses, have been detected in aerosols in the air in healthcare settings for some respiratory viruses such as seasonal and avian influenza viruses, Middle East respiratory syndrome-coronavirus and respiratory syncytial virus. However, current evidences are yet to demonstrate that these viruses can effectively spread via airborne route between individuals, or whether preventive measures in airborne precautions would be effective. SUMMARY Studies that use transmission events as outcome to demonstrate human-to-human transmission over the aerosol route or quantitative measurement of infectious respiratory viruses in the air are needed to evaluate the infectiousness of respiratory viruses over the aerosol route. When a respiratory virus in concern only leads to disease with low severity, airborne precautions are not likely to be justified.

Title: SARS‐CoV‐2 possible contamination of genital area: implications for sexual and vertical transmission routes Content: The severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2) is responsible for a pandemic that is causing thousands of deaths worldwide. The virus can be transmitted from person to person, directly or indirectly, via the respiratory, oro‐fecal and probably sexual routes.(1) The eventual vertical transmission route is still poorly explored. However, mother‐to‐child SARS‐CoV‐2 transmission through the placenta probably does not occur, or likely occurs very rarely.(2) All the studies conducted on COVID‐19 pregnant women involved patients undergoing cesarean section, but the indications for such delivery modality were not clearly stated.

Title: Multi-route respiratory infection: when a transmission route may dominate Content: The exact transmission route of many respiratory infectious diseases remains a subject for debate to date. The relative contribution ratio of each transmission route is largely undetermined, which is affected by environmental conditions, human behavior, the host and the microorganism. In this study, a detailed mathematical model is developed to investigate the relative contributions of different transmission routes to a multi-route transmitted respiratory infection. It is illustrated that all transmission routes can dominate the total transmission risk under different scenarios. Influential parameters considered include dose-response rate of different routes, droplet governing size that determines virus content in droplets, exposure distance, and virus dose transported to the hand of infector. Our multi-route transmission model provides a comprehensive but straightforward method to evaluate the transmission efficiency of different transmission routes of respiratory diseases and provides a basis for predicting the impact of individual level intervention methods such as increasing close-contact distance and wearing protective masks.

Title: Novel analytic tools for the study of porcine reproductive and respiratory syndrome virus (PRRSv) in endemic settings: lessons learned in the U.S. Content: Since its emergence in the late 1980’s, the porcine reproductive and respiratory syndrome virus (PRRSv) has posed a significant challenge to the pig industry worldwide. Since then, a number of epidemiological tools have been created to support control and eventual elimination of the disease at the farm and regional levels. Still, many aspects of the disease dynamics are yet-to-be elucidated, such as what are the economically optimal control strategies at the farm and regional level, what is the role that the voluntary regional control programs may play, how to optimize the use of molecular tools for surveillance and monitoring in infected settings, what is the full impact of the disease in a farm, or what is the relative contribution of alternative transmission routes on the occurrence of PRRSv outbreaks. Here, we summarize a number of projects demonstrating the use of novel analytical tools in the assessment of PRRSv epidemiology in the United States. Results presented demonstrate how quantitative analysis of routinely collected data may help in understanding regional epidemiology of PRRSv and to quantify its full impact, and how the integration of phylodynamic methods as a standard tool for molecular surveillance of PRRSv might help to inform control and prevention strategies in high-risk epidemiological situations. Ultimately, these tools will help to support PRRSv control at farm and regional levels in endemically infected settings.

Title: Preliminary investigation on feline coronavirus presence in the reproductive tract of the tom cat as a potential route of viral transmission Content: OBJECTIVES: Feline infectious peritonitis (FIP) is an immune-mediated disease initiated by feline coronavirus (FCoV) infection. To date, the only proven route of transmission is the faecal–oral route, but a possible localisation of FCoV in the reproductive tract of tom cats is of concern, owing to the involvement of the male reproductive tract during FIP and to the presence of reproduction disorders in FCoV-endemic feline catteries. The aim of the study was to investigate the presence and localisation of FCoV in semen and/or in the reproductive tract of tom cats, and its possible association with seroconversion and viraemic phase. METHODS: Blood, serum, semen and/or testicle samples were obtained from 46 tom cats. Serology was performed on 38 serum samples, nested reverse transcriptase PCR (nRT-PCR) and reverse transcriptase quantitative PCR (RT-qPCR) were performed on 39 blood samples and on 17 semen samples, and histology, immunohistochemistry and nRT-PCR were performed on 39 testicles. RESULTS: Twenty-four of 38 serum samples were positive on serology. Semen samples were negative on RT-PCR and RT-qPCR for FCoV, while all blood samples were negative at both molecular methods, except for one sample positive at RT-qPCR with a very low viral load. All testicles were negative at immunohistochemistry, while six were positive at nRT-PCR for FCoV. Serology and blood PCR results suggest that the virus was present in the environment, stimulating transient seroconversion. FCoV seems not to localise in the semen of tom cats, making the venereal route as a way of transmission unlikely. Although viral RNA was found in some testicles, it could not be correlated with the viraemic phase. CONCLUSIONS AND RELEVANCE: In the light of these preliminary results, artificial insemination appears safer than natural mating as it eliminates the direct contact between animals, thus diminishing the probability of faecal–oral FCoV transmission.

Title: COVID-19 vulnerability: the potential impact of genetic susceptibility and airborne transmission Content: The recent coronavirus disease (COVID-19), caused by SARS-CoV-2, is inarguably the most challenging coronavirus outbreak relative to the previous outbreaks involving SARS-CoV and MERS-CoV. With the number of COVID-19 cases now exceeding 2 million worldwide, it is apparent that (i) transmission of SARS-CoV-2 is very high and (ii) there are large variations in disease severity, one component of which may be genetic variability in the response to the virus. Controlling current rates of infection and combating future waves require a better understanding of the routes of exposure to SARS-CoV-2 and the underlying genomic susceptibility to this disease. In this mini-review, we highlight possible genetic determinants of COVID-19 and the contribution of aerosol exposure as a potentially important transmission route of SARS-CoV-2.

Title: Transmission of SARS-CoV-2 via fecal-oral and aerosols-borne routes: Environmental dynamics and implications for wastewater management in underprivileged societies Content: The advent of novel human coronavirus (SARS-CoV-2) and its potential transmission via fecal-oral and aerosols-borne routes are upcoming challenges to understand the fate of the virus in the environment. In this short communication, we specifically looked at the possibilities of these transmission routes based on the available literature directly related to the SARS-CoV-2 as well as on the closer phylogenetic relatives such as SARS-CoV-1. The available data suggest that, in addition to human-to-human contact, the virus may spread via fecal-oral and aerosols-borne routes. Existing knowledge states that coronaviruses have low stability in the environment due to the natural action of oxidants that disrupt the viral envelope. Previous recommended dosage of chlorination has been found to be not sufficient to inactivate SARS-CoV-2 in places where viral load is high such as hospitals and airports. Although there is no current evidence showing that coronaviruses can be transmitted through contaminated drinking water, there is a growing concern on the impact of the current pandemic wave on underprivileged societies because of their poor wastewater treatment infrastructures, overpopulation, and outbreak management strategies. More research is encouraged to trace the actual fate of SARS-CoV-2 in the environment and to develop/revise the disinfection strategies accordingly.

Title: Transmission of SARS-CoV-2 via fecal-oral and aerosols–borne routes: Environmental dynamics and implications for wastewater management in underprivileged societies Content: Abstract The advent of novel human coronavirus (SARS-CoV-2) and its potential transmission via fecal-oral and aerosols-borne routes are upcoming challenges to understand the fate of the virus in the environment. In this short communication, we specifically looked at the possibilities of these transmission routes based on the available literature directly related to the SARS-CoV-2 as well as on the closer phylogenetic relatives such as SARS-CoV-1. The available data suggest that, in addition to human-to-human contact, the virus may spread via fecal-oral and aerosols-borne routes. Existing knowledge states that coronaviruses have low stability in the environment due to the natural action of oxidants that disrupt the viral envelope. Previous recommended dosage of chlorination has been found to be not sufficient to inactivate SARS-CoV-2 in places where viral load is high such as hospitals and airports. Although there is no current evidence showing that coronaviruses can be transmitted through contaminated drinking water, there is a growing concern on the impact of the current pandemic wave on underprivileged societies because of their poor wastewater treatment infrastructures, overpopulation, and outbreak management strategies. More research is encouraged to trace the actual fate of SARS-CoV-2 in the environment and to develop/revise the disinfection strategies accordingly.

Title: Emerging coronaviruses: first SARS, second MERS and third SARS-CoV-2: epidemiological updates of COVID-19. Content: Since December 2019, the emergence of the Severe Acute Respiratory Syndrome Coronavirus (SARS-CoV-2) infection has been reported unexpectedly in Wuhan, China, with staggering infection speed across China and around the world. To date, seven known strains of HCoVs belonging to four genera (i.e., α?, β?, γ, and δ-CoV) have been recognized; the latest one has been identified as the SARS-CoV-2. Although the common transmission routes of SARS-CoV-2 is the respiratory tract, it seems that other routes such as the gastrointestinal tract may be effective for the entry of the virus in the body. Although there are no biological markers to predict the susceptibility of humans to COVID-19, several risk factors have been identified to predict the susceptibility of patients to COVID-19. Initial data revealed that males, pregnant women, elderly, and underlying conditions predispose patients to higher morbidity or mortality and also might be at risk for a severe infection of COVID-19. There is a greater need to better understand the mechanisms and risk factors of transmission routes. To date, despite the whole world effort to review various aspects of SARS-CoV-2, including epidemiology, clinical manifestations, diagnosis, and treatment options, there are still gaps in the knowledge of this disease and many issues remain unclear. Therefore, there is an urgent need for update data on SARS-CoV-2. Here, this study provide the current epidemiological status (transmission routes and risk of transmission, possible origins and source, mortality and morbidity risk, and geographical distribution) of the SARS-CoV-2 in the world in 2020.

Title: Emerging coronaviruses: first SARS, second MERS and third SARS-CoV-2: epidemiological updates of COVID-19 Content: Since December 2019, the emergence of the Severe Acute Respiratory Syndrome Coronavirus (SARS-CoV-2) infection has been reported unexpectedly in Wuhan, China, with staggering infection speed across China and around the world To date, seven known strains of HCoVs belonging to four genera (i e , alpha?, beta?, gamma, and delta-CoV) have been recognized;the latest one has been identified as the SARS-CoV-2 Although the common transmission routes of SARS-CoV-2 is the respiratory tract, it seems that other routes such as the gastrointestinal tract may be effective for the entry of the virus in the body Although there are no biological markers to predict the susceptibility of humans to COVID-19, several risk factors have been identified to predict the susceptibility of patients to COVID-19 Initial data revealed that males, pregnant women, elderly, and underlying conditions predispose patients to higher morbidity or mortality and also might be at risk for a severe infection of COVID-19 There is a greater need to better understand the mechanisms and risk factors of transmission routes To date, despite the whole world effort to review various aspects of SARS-CoV-2, including epidemiology, clinical manifestations, diagnosis, and treatment options, there are still gaps in the knowledge of this disease and many issues remain unclear Therefore, there is an urgent need for update data on SARS-CoV-2 Here, this study provide the current epidemiological status (transmission routes and risk of transmission, possible origins and source, mortality and morbidity risk, and geographical distribution) of the SARS-CoV-2 in the world in 2020

Title: Recreational waters - A potential transmission route for SARS-CoV-2 to humans? Content: Coronavirus disease 2019 (COVID-19), the respiratory illness caused by the novel virus, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), which has lead to high morbidity and mortality rates worldwide, has been causing major public health concerns since first detected in late 2019. Following identification of novel pathogens, questions in relation to dissemination of the pathogen and transmission routes begin to emerge. This rapidly spreading SARS-CoV-2 virus has been detected in both faecal and wastewater samples across the globe, highlighting the potential for faecal-oral transmission of the virus. As a result, concerns regarding the transmission of the virus in the environment and the risk associated with contracting the virus in recreational waters, particularly where inadequately treated wastewater is discharged, have been emerging in recent weeks. This paper highlights the need for further research to be carried out to investigate the presence, infectivity and viability of this newly identified SARS-CoV-2 virus in wastewater effluent and receiving recreational waters.

Title: Recreational waters – A potential transmission route for SARS-CoV-2 to humans? Content: Coronavirus disease 2019 (COVID-19), the respiratory illness caused by the novel virus, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), which has lead to high morbidity and mortality rates worldwide, has been causing major public health concerns since first detected in late 2019. Following identification of novel pathogens, questions in relation to dissemination of the pathogen and transmission routes begin to emerge. This rapidly spreading SARS-CoV-2 virus has been detected in both faecal and wastewater samples across the globe, highlighting the potential for faecal-oral transmission of the virus. As a result, concerns regarding the transmission of the virus in the environment and the risk associated with contracting the virus in recreational waters, particularly where inadequately treated wastewater is discharged, have been emerging in recent weeks. This paper highlights the need for further research to be carried out to investigate the presence, infectivity and viability of this newly identified SARS-CoV-2 virus in wastewater effluent and receiving recreational waters.

Title: What makes a foodborne virus: comparison between coronaviruses with human noroviruses Content: In order to answer the question whether coronaviruses (CoVs) can be transmitted via foods, this review made a comparison between CoVs with the most recognized foodborne virus, human noroviruses (NoVs). As a result, although CoVs indeed have shown the possibilities to remain infectious on foods and/or food packaging materials long enough (from several days to several weeks) to potentially cause transmission, they seem to be less persistent than NoVs towards common disinfection practices with alcohols, chlorine and ultraviolet (UV). More importantly, the chance of foodborne transmission of CoVs is considered low as CoVs mainly spread through the respiratory tract and there is no clear evidence showing CoVs can follow fecal-oral routes like human NoVs and other foodborne viruses.

Title: Facemasks prevent influenza-like illness: implications for COVID-19 Content: The coronavirus disease 2019 (COVID-19) pandemic is causing a huge toll on individuals, families, communities and societies across the world. Currently, whether wearing facemasks in public should be a measure to prevent transmission of severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) remains contraversial.1 This is largely because there have been no randomized controlled trials (RCTs) for coronavirus to directly support this. However, lessons may be taken from published RCTs examining influenza-like illness (ILI).2,3 Recent studies suggested that SARS-CoV-2 shares similar transmission route with influenza virus,4 and the incidence of community transmission of SARS-CoV-2 in individuals with ILI is high.5 Therefore, we undertook this meta-analysis of RCTs examining the efficacy of wearing facemasks to prevent ILI in community settings, irrespective of confirmatory testing for the causative virus. We undertook a systematic literature search for RCTs related to facemasks and ILI between 1966 and April 2020 using PUBMED, EMBASE, and Cochrane library. RCTs undertaken in community (not hospital) settings comparing wearing and not wearing facemasks for ILI were included. Incidence of ILI (e.g., fever, cough, headache, sore throat, aches or pains in muscles or joints) was estimated per group. Relative risk (RR) and 95% confidence interval (CI) were calculated. We screened 899 related abstracts and eventually included 8 RCTs (Figure S1). Basic characteristics and quality of included RCTs are listed in Supplement. Participants wearing facemasks had a significantly lower risk of developing ILI than those not wearing facemasks (pooled RR=0.81, 95% CI: 0.70-0.95) and there was no heterogeneity (Figure 1). The decreased risk of ILI was more pronounced if everyone wore facemask irrespective of whether they were infected or not (RR=0.77, 95% CI: 0.65-0.91), compared to those wearing facemasks when infected (RR=0.95, 95% CI: 0.58-1.56) or uninfected (RR=1.26, 95% CI: 0.69-2.31). This study shows that wearing facemasks, irrespective of infection status, is effective in preventing ILI spread in the community. This situation mirrors what is happening now in public settings where we do not know who has been infected and who has not. Although there are no RCTs of facemasks for SARS-CoV-2, as with other simple measures such as social distancing and handwashing, these data support the recommendation to wear facemasks in public to further reduce transmission of SARS-CoV-2 and flatten the curve of this pandemic, especially when social distancing is impractical, such as shopping, or travelling with public transport for work that cannot be done from home.

Title: Transmission of SARS-CoV-2, Required Developments in Research and Associated Public Health Concerns Content: Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is rapidly spreading across the world to cause thousands of mortalities each day. Poor responses from the authorities to the spread of infection, lack of effective measures for prevention, unavailability of promising treatment options, and sufficient diagnostic options have created an alarming for the world. The transmission routes from human to human of SARS-CoV-2 can be the direct transmission, droplet inhalation transmission, contact transmission, transmission through saliva, and transmission via fecal–oral routes. Due to the asymptomatic spread of SARS-CoV-2's, developing control and prevention measures is challenging. Implementing proper strategies addressing the infection control and clinical supplies, understanding the mechanism associated with pathogenesis, advancing in preventive measures and effective treatment and diagnostic options are necessary to control the ongoing pandemic. In this article, we briefly discuss the features, entry mechanism, infectiousness, and health consequences related to the COVID-19 outbreak.

Title: Deep phylogenetic analysis of Orthocoronavirinae genomes traces the origin, evolution and transmission route of 2019 novel coronavirus Content: The outbreak of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in Wuhan city, China in December 2019 and thereafter its spillover across the world has created a global pandemic and public health crisis. Today, it appears as a threat to human civilization. Scientists and medical practitioners across the world are involved to trace out the origin and evolution of SARS-CoV-2 (also called 2019 novel coronavirus and referred as 2019-nCoV), its transmission route, cause of pathogenicity, and possible remedial action. In this work, we aim to find out the origin, evolutionary patternthat led to its pathogenicity and possible transmission pathway of 2019-nCoV. To achieve the aims we conducted a large-scale deep phylogenetic analysis on the 162 complete Orthocoronavirinae genomes consisting of four genera namely Alphacoronavirus, Betacoronavirus, Deltacoronavirus and Gammacoronavirus, their gene trees analysis and subsequently genome and gene recombination analyses. Our analyses revealed that i) bat, pangolin and anteater are the natural hosts of 2019-nCoV, ii) outbreak of 2019-nCoV took place via inter-intra species transmission mode, iii) host-specific adaptive mutation made 2019-nCoV more virulent, and the presence of widespread recombination events led to the evolution of new 2019-nCoV strain and/or could be determinant of its pathogenicity. Highlights Orthocoronavirinae genome phylogeny revealed that bat, pangolin and anteater are natural reservoir hosts of novel coronavirus (2019-nCoV/SARS-CoV-2). Host-specific adaptive mutation occurred among the coronaviruses. Transmission of 2019-nCoV to human took place by inter-intra species mode of transmission. Presence of widespread recombination events led to the evolution of new 2019-nCoV strain and/or could be determinant of its pathogenicity.

Title: The epidemic of 2019-novel-coronavirus (2019-nCoV) pneumonia and insights for emerging infectious diseases in the future Content: At the end of December 2019, a novel coronavirus, 2019-nCoV, caused an outbreak of pneumonia spreading from Wuhan, Hubei province, to the whole country of China, which has posed great threats to public health and attracted enormous attention around the world. To date, there are no clinically approved vaccines or antiviral drugs available for these human coronavirus infections. Intensive research on the novel emerging human infectious coronaviruses is urgently needed to elucidate their route of transmission and pathogenic mechanisms, and to identify potential drug targets, which would promote the development of effective preventive and therapeutic countermeasures. Herein, we describe the epidemic and etiological characteristics of 2019-nCoV, discuss its essential biological features, including tropism and receptor usage, summarize approaches for disease prevention and treatment, and speculate on the transmission route of 2019-nCoV.

Title: The epidemic of 2019-novel-coronavirus (2019-nCoV) pneumonia and insights for emerging infectious diseases in the future Content: Abstract At the end of December 2019, a novel coronavirus, 2019-nCoV, caused an outbreak of pneumonia spreading from Wuhan, Hubei province, to the whole country of China, which has posed great threats to public health and attracted enormous attention around the world. To date, there are no clinically approved vaccines or antiviral drugs available for these human coronavirus infections. Intensive research on the novel emerging human infectious coronaviruses is urgently needed to elucidate their route of transmission and pathogenic mechanisms, and to identify potential drug targets, which would promote the development of effective preventive and therapeutic countermeasures. Herein, we describe the epidemic and etiological characteristics of 2019-nCoV, discuss its essential biological features, including tropism and receptor usage, summarize approaches for disease prevention and treatment, and speculate on the transmission route of 2019-nCoV.

Title: A scoping review on bio-aerosols in healthcare and the dental environment Content: BACKGROUND: Bio-aerosols originate from different sources and their potentially pathogenic nature may form a hazard to healthcare workers and patients. So far no extensive review on existing evidence regarding bio-aerosols is available. OBJECTIVES: This study aimed to review evidence on bio-aerosols in healthcare and the dental setting. The objectives were 1) What are the sources that generate bio-aerosols?; 2) What is the microbial load and composition of bio-aerosols and how were they measured?; and 3) What is the hazard posed by pathogenic micro-organisms transported via the aerosol route of transmission? METHODS: Systematic scoping review design. Searched in PubMed and EMBASE from inception to 09-03-2016. References were screened and selected based on abstract and full text according to eligibility criteria. Full text articles were assessed for inclusion and summarized. The results are presented in three separate objectives and summarized for an overview of evidence. RESULTS: The search yielded 5,823 studies, of which 62 were included. Dental hand pieces were found to generate aerosols in the dental settings. Another 30 sources from human activities, interventions and daily cleaning performances in the hospital also generate aerosols. Fifty-five bacterial species, 45 fungi genera and ten viruses were identified in a hospital setting and 16 bacterial and 23 fungal species in the dental environment. Patients with certain risk factors had a higher chance to acquire Legionella in hospitals. Such infections can lead to irreversible septic shock and death. Only a few studies found that bio-aerosol generating procedures resulted in transmission of infectious diseases or allergic reactions. CONCLUSION: Bio-aerosols are generated via multiple sources such as different interventions, instruments and human activity. Bio-aerosols compositions reported are heterogeneous in their microbiological composition dependent on the setting and methodology. Legionella species were found to be a bio-aerosol dependent hazard to elderly and patients with respiratory complaints. But all aerosols can be can be hazardous to both patients and healthcare workers.

Title: Transmission of SARS-CoV-2: an update of current literature Content: Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the etiologic agent for the 2019 coronavirus disease (COVID-19) pandemic, has caused a public health emergency. The need for additional research in viral pathogenesis is essential as the number of cases and deaths rise. Understanding the virus and its ability to cause disease has been the main focus of current literature; however, there is much unknown. Studies have revealed new findings related to the full transmission potential of SARS-CoV-2 and its subsequent ability to cause infection by different means. The virus is hypothesized to be of increased virulence compared with previous coronavirus that caused epidemics, in part due to its overall structural integrity and resilience to inactivation. To date, many studies have discussed that the rationale behind its transmission potential is that viral RNA has unexpectedly been detected in multiple bodily fluids, with some samples having remained positive for extended periods of time. Additionally, the receptor by which the virus gains cellular entry, ACE2, has been found to be expressed in different human body systems, thereby potentiating its infection in those locations. In this evidence-based comprehensive review, we discuss various potential routes of transmission of SARS-CoV-2—respiratory/droplet, indirect, fecal-oral, vertical, sexual, and ocular. Understanding these different routes is important as they pertain to clinical practice, especially in taking preventative measures to mitigate the spread of SARS-CoV-2.

Title: A new transmission route for the propagation of the SARS-CoV-2 coronavirus Content: We explore here how variation in the SARS-CoV-2 virus tropism could influence epidemic spread. We use a compartmental model fit to the existing data. The model indicates that Wuhan quarantine measures were effective but that alternative virus forms (gut tropism) and a second propagation route (through environment) was present. For Singapore and Shenzhen region the secondary route does not seem to be active yet. Adequate prevention measures taking into account both routes should be implemented.

Title: Is sweat a possible route of transmission of SARS-CoV-2? Content: Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has caused a global pandemic, in part due to the highly infectious nature of the disease. Because SARS-CoV-2 is new, much is unknown regarding mechanisms of transmission, and such information is urgently needed. Here, based on previous findings from related human betacoronaviruses, it is suggested that one possible route of transmission may be via infectious sweat. It is suggested that research be conducted in order to determine whether sweat in SARS-CoV-2 infected individuals harbors virus in quantities that can infect others. Findings could be used for formulations of mitigation strategies and empirically based public health messaging.

Title: Probable transmission routes of the influenza virus in a nosocomial outbreak. Content: Influenza is a long-standing public health concern, but its transmission remains poorly understood. To have a better knowledge of influenza transmission, we carried out a detailed modelling investigation in a nosocomial influenza outbreak in Hong Kong. We identified three hypothesised transmission modes between index patient and other inpatients based on the long-range airborne and fomite routes. We considered three kinds of healthcare workers' routine round pathways in 1140 scenarios with various values of important parameters. In each scenario, we used a multi-agent modelling framework to estimate the infection risk for each hypothesis and conducted least-squares fitting to evaluate the hypotheses by comparing the distribution of the infection risk with that of the attack rates. Amongst the hypotheses tested in the 1140 scenarios, the prediction of modes involving the long-range airborne route fit better with the attack rates, and that of the two-route transmission mode had the best fit, with the long-range airborne route contributing about 94% and the fomite route contributing 6% to the infections. Under the assumed conditions, the influenza virus was likely to have spread via a combined long-range airborne and fomite routes, with the former predominant and the latter negligible.

Title: A Review on 2019 Novel Coronavirus Pneumonia in Ophthalmology. Content: Purpose: To investigate the possibility of ocular involvement in the 2019-novel coronavirus infectious (2019-nCoV) and vital preventive measures in the field of ophthalmology.Methods: All the studies that were most relevant to the 2019-nCoV ocular involvement and routes of transmission, especially in the field of ophthalmology, thoroughly reviewed.Results: From the ocular perspective, conjunctivitis may be the first presenting symptom of 2019-nCoV, so, we as ophthalmologists are at the forefront of exposure with newly infected patients. Although transconjunctival aerosol is a suspected but, the main route of transmission is the known respiratory droplets which will be more significant due to close contact in the field of ophthalmology. This review advise a set of recommendation for preventive care to minimize cross-infection of 2019-nCoV.Conclusions: Ophthalmologists have an essential role in guiding cross-infection control measures between patients and staff. Until a vaccine is created, public health strategies are likely the best weapons against this invisible enemy.

Title: A Review on 2019 Novel Coronavirus Pneumonia in Ophthalmology Content: Purpose: To investigate the possibility of ocular involvement in the 2019-novel coronavirus infectious (2019-nCoV) and vital preventive measures in the field of ophthalmology.Methods: All the studies that were most relevant to the 2019-nCoV ocular involvement and routes of transmission, especially in the field of ophthalmology, thoroughly reviewed.Results: From the ocular perspective, conjunctivitis may be the first presenting symptom of 2019-nCoV, so, we as ophthalmologists are at the forefront of exposure with newly infected patients. Although transconjunctival aerosol is a suspected but, the main route of transmission is the known respiratory droplets which will be more significant due to close contact in the field of ophthalmology. This review advise a set of recommendation for preventive care to minimize cross-infection of 2019-nCoV.Conclusions: Ophthalmologists have an essential role in guiding cross-infection control measures between patients and staff. Until a vaccine is created, public health strategies are likely the best weapons against this invisible enemy.

Title: Fomite-mediated transmission as a sufficient pathway: a comparative analysis across three viral pathogens Content: BACKGROUND: Fomite mediated transmission can be an important pathway causing significant disease transmission in number of settings such as schools, daycare centers, and long-term care facilities. The importance of these pathways relative to other transmission pathways such as direct person-person or airborne will depend on the characteristics of the particular pathogen and the venue in which transmission occurs. Here we analyze fomite mediated transmission through a comparative analysis across multiple pathogens and venues. METHODS: We developed and analyzed a compartmental model that explicitly accounts for fomite transmission by including pathogen transfer between hands and surfaces. We consider two sub-types of fomite-mediated transmission: direct fomite (e.g., shedding onto fomites) and hand-fomite (e.g., shedding onto hands and then contacting fomites). We use this model to examine three pathogens with distinct environmental characteristics (influenza, rhinovirus, and norovirus) in four venue types. To parameterize the model for each pathogen we conducted a thorough literature search. RESULTS: Based on parameter estimates from the literature the reproductive number ([Formula: see text] ) for the fomite route for rhinovirus and norovirus is greater than 1 in nearly all venues considered, suggesting that this route can sustain transmission. For influenza, on the other hand, [Formula: see text] for the fomite route is smaller suggesting many conditions in which the pathway may not sustain transmission. Additionally, the direct fomite route is more relevant than the hand-fomite route for influenza and rhinovirus, compared to norovirus. The relative importance of the hand-fomite vs. direct fomite route for norovirus is strongly dependent on the fraction of pathogens initially shed to hands. Sensitivity analysis stresses the need for accurate measurements of environmental inactivation rates, transfer efficiencies, and pathogen shedding. CONCLUSIONS: Fomite-mediated transmission is an important pathway for the three pathogens examined. The effectiveness of environmental interventions differs significantly both by pathogen and venue. While fomite-based interventions may be able to lower [Formula: see text] for fomites below 1 and interrupt transmission, rhinovirus and norovirus are so infectious ([Formula: see text] ) that single environmental interventions are unlikely to interrupt fomite transmission for these pathogens. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (10.1186/s12879-018-3425-x) contains supplementary material, which is available to authorized users.

Title: Comparison of the COVID-19 infection risks by close contact and aerosol transmission Content: A comprehensive understanding of the transmission routes of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is of great importance for the effective control of the spread of Corona Virus Disease 2019 (COVID-19). Human-to-human transmission by close contact where large respiratory droplets play a significant role has been established as the main transmission route. At the same time the transmission by small aerosol is getting increasing attention. There is no distinct boundary between droplets and aerosol in nature so it is natural to investigate the infection risk due to aerosol. Here, we utilized a newly developed dose-response relation, combined with a box model for the exposure estimation, to quantitatively evaluate the infection risk of SARS-CoV-2 through aerosol transmission and compared with the risk due to close contact. The results indicated that the median infection risk via aerosol transmission was about 3.7x10-5 (95% confidence interval: 3.5x10-6 to 4.4x10-4) for one hour of exposure in a room with the size of 10 m (width)x10 m (length)x3 m (height) with one infected individual in it. The risk was more than three orders of magnitude lower than the risk at short distance, about 12.8% within 1 m, based on a meta-analysis. A simple exponential regression model Risk=10-0.90xD+0.10 (D<=5 m) could be utilized to characterize the magnitude of infection risk in the considered scenario based on the distance D from the infected individual. With prolonged exposure duration and large exposed population, the infection caused by aerosol transmission could be considerable, thus it is necessary to be cautious for the potential aerosol transmission risk in such situations.

Title: Vaccine Strategies Content: The new technologies of genomics, proteomics, and molecular immunology have led to an impressive increase in our knowledge of all aspects of virology, providing insights that can guide new vaccine concepts. When developing a new vaccine, the choice of approach is made very much on a case-by-case basis, and for a given virus is driven by knowledge its pathogenesis, serotype diversity, antigenic variation, immune evasion mechanisms, latency and route of transmission. High importance is given to what type of immunity arises as a result of natural infection and whether the pathogen can cause persistent and/or repeated infections in a single host. This article discusses the medical need for new human viral vaccines and focuses on the strategies available for their development and some of the challenges posed by the more difficult targets.

Title: Transmission routes of respiratory viruses among humans Content: Respiratory tract infections can be caused by a wide variety of viruses. Airborne transmission via droplets and aerosols enables some of these viruses to spread efficiently among humans, causing outbreaks that are difficult to control. Many outbreaks have been investigated retrospectively to study the possible routes of inter-human virus transmission. The results of these studies are often inconclusive and at the same time data from controlled experiments is sparse. Therefore, fundamental knowledge on transmission routes that could be used to improve intervention strategies is still missing. We here present an overview of the available data from experimental and observational studies on the transmission routes of respiratory viruses between humans, identify knowledge gaps, and discuss how the available knowledge is currently implemented in isolation guidelines in health care settings.

Title: Coronavirus disease 2019 (COVID-19): research progress and clinical practice Content: Coronavirus disease 2019 (COVID-19) is a respiratory tract infection caused by SARS-CoV-2 As of March 30, 2020, there have been 693,224 reported patients with COVID-19 worldwide, with 1,446 in Japan Currently, although aspects of the route of transmission are unclear, infection by contact and by inhaling droplets is considered to be the dominant transmission route Inflammatory symptoms in the upper respiratory tract persist for several days to 1 week after onset, and in some patients symptoms of pneumonia worsen and become severe The presence of underlying diseases and advanced age are risk factors for increased severity Diagnosis is based on detection of SARS-CoV-2 by polymerase chain reaction (PCR) testing of nasopharyngeal swabs or sputum Symptomatic management is the main treatment for this disease Although the efficacy of several agents is currently being tested, at present there is no effective therapeutic agent To prevent infection, in addition to standard preventive measures, measures that counteract infection by contact and droplet inhalation are important In addition, if procedures that cause aerosolization of virus are used, then measures that prevent airborne infection should be implemented

Title: Airborne or Fomite Transmission for Norovirus? A Case Study Revisited Content: Norovirus infection, a highly prevalent condition associated with a high rate of morbidity, comprises a significant health issue. Although norovirus transmission mainly occurs via the fecal-oral and vomit-oral routes, airborne transmission has been proposed in recent decades. This paper re-examines a previously described norovirus outbreak in a hotel restaurant wherein airborne transmission was originally inferred. Specifically, the original evidence that suggested airborne transmission was re-analyzed by exploring an alternative hypothesis: could this outbreak instead have occurred via fomite transmission? This re-analysis was based on whether fomite transmission could have yielded similar attack rate distribution patterns. Seven representative serving pathways used by waiters were considered, and the infection risk distributions of the alternative fomite transmission routes were predicted using a multi-agent model. These distributions were compared to the reported attack rate distribution in the original study using a least square methods approach. The results show that with some reasonable assumptions of human behavior patterns and parameter values, the attack rate distribution corresponded well with that of the infection risk via the fomite route. This finding offers an alternative interpretation of the transmission routes that underlay this particular norovirus outbreak and an important consideration in the development of infection control guidelines and the investigation of similar norovirus outbreaks in future.

Title: Exploration of the Effectiveness of Social Distancing on Respiratory Pathogen Transmission Implicates Environmental Contributions Content: Background. In both military and civilian settings, transmission of respiratory pathogens may be due to person-to-person and environmental contributions. This possibility was explored in a military training setting, where rates of febrile respiratory illness (FRI) often reach epidemic levels. Methods. Population size and FRI rates were monitored over 10 months in the units of 50–90 individuals. Some units were open to the influx of potentially infectious convalescents (hereafter referred to as “open units,” and some were closed to such an influx (hereafter referred to as “closed units”). Virologic testing and polymerase chain reaction analysis were used to detect adenovirus on surface structures. Results. The odds ratio (OR) associated with FRI in closed units, compared with open units, was 1.13 (95% confidence interval [CI], 0.99–1.28). The OR in units with a population greater than the median size, compared with units with a population lower than the median size was 1.38 (95% CI, 1.23–1.55). Between 5% and 9% of surface samples obtained from selected units harbored viable adenovirus. Conclusions. FRI rates were not reduced in units that were closed to potentially contagious individuals. These findings imply that the primary source of the pathogen is likely environmental rather than human, and they underscore what is known about other virus types. Diligence in identifying the relative roles of different transmission routes is suggested for civilian settings similar to those described in the current study.

Title: A Mathematical Framework for Predicting Lifestyles of Viral Pathogens Content: Despite being similar in structure, functioning, and size, viral pathogens enjoy very different, usually well-defined ways of life. They occupy their hosts for a few days (influenza), for a few weeks (measles), or even lifelong (HCV), which manifests in acute or chronic infections. The various transmission routes (airborne, via direct physical contact, etc.), degrees of infectiousness (referring to the viral load required for transmission), antigenic variation/immune escape and virulence define further aspects of pathogenic lifestyles. To survive, pathogens must infect new hosts; the success determines their fitness. Infection happens with a certain likelihood during contact of hosts, where contact can also be mediated by vectors. Besides structural aspects of the host-contact network, three parameters appear to be key: the contact rate and the infectiousness during contact, which encode the mode of transmission, and third the immunity of susceptible hosts. On these grounds, what can be said about the reproductive success of viral pathogens? This is the biological question addressed in this paper. The answer extends earlier results of the author and makes explicit connection to another basic work on the evolution of pathogens. A mathematical framework is presented that models intra- and inter-host dynamics in a minimalistic but unified fashion covering a broad spectrum of viral pathogens, including those that cause flu-like infections, childhood diseases, and sexually transmitted infections. These pathogens turn out as local maxima of numerically simulated fitness landscapes. The models involve differential and integral equations, agent-based simulation, networks, and probability.

Title: [Strengthening basic and clinical research on ocular infection caused by coronavirus]. Content: This article was published ahead of print on the official website of Chinese Jounal of Ophthalmology on February 19, 2020. The prevention and treatment of coronavirus disease 2019 (COVID-2019) has reached the critical stage in China. Ocular surface represents a possible route for infection. Based on the previous studies and our own research, we summarize the potential transmission route and clinical symptoms of COVID-2019 in the eye, as well as the further prevention and research, with the expectation of contributing to the development in the field of infectious eye disease in China. (Chin J Ophthalmol, 2020, 56:250-252).

Title: Potential fecal transmission of SARS-CoV-2: Current evidence and implications for public health Content: Coronavirus disease 2019 (COVID-19) emerged in Hubei Province, China in December 2019 and has since become a global pandemic, with hundreds of thousands of cases and over 165 countries affected. Primary routes of transmission of the causative virus, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), are through respiratory droplets and close person-to-person contact. While information about other potential modes of transmission are relatively sparse, evidence supporting the possibility of a fecally mediated mode of transmission has been accumulating. Here, current knowledge on the potential for fecal transmission is briefly reviewed and the possible implications are discussed from a public health perspective.

Title: Potential Fecal Transmission of SARS-CoV-2: Current Evidence and Implications for Public Health Content: Abstract Coronavirus disease 2019 (COVID-19) emerged in Hubei Province, China in December 2019 and has since become a global pandemic, with hundreds of thousands of cases and over 165 affected countries. Primary routes of transmission of the causative virus, severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2), are through respiratory droplets and close person-to-person contact. While information about other potential modes of transmission are relatively sparse, evidence supporting the possibility of a fecally-mediated mode of transmission has been accumulating. Here, current knowledge on the potential for fecal transmission is briefly reviewed and the possible implications are discussed from a public health perspective.

Title: Observations about sexual and other routes of SARS‐CoV‐2 (COVID‐19) transmission and its prevention Content: Sexual contact has been proposed as a route of transmission for the SARS-CoV-2 virus, which raises the question of alternate routes of transmission.

Title: Overview of new vaccines and technologies Content: Abstract Molecular technology has given us a greater insight into the aetiology of disease, the functioning of the immune system and the mode of action of veterinary pathogens. The knowledge gained has been used to develop new vaccines with specific, reactive antigens which elicit protective immune mediated responses (humoral and/or cell mediated) in the host. These vaccines should not burden the immune system by initiating responses against non-essential antigens. However, the efficacy of these vaccines is only as good as the delivery technology or route used to present them to the immune system. Some vaccines, traditionally given by the parenteral route, are now given by the natural route; either orally or intranasally. Two major advantages, often interrelated, are the rapid onset of immunity and stimulation of the local, mucosal immunity. These new technologies are now making an impact on current vaccine development. The balance has to be found between what is technologically feasible and what will provide at least as good a protective immunity as current, conventional vaccines. As new and emerging diseases appear globally, new opportunities arise for molecular and conventional technologies to be applied to both the development and delivery of novel vaccines, as well as the improvement of vaccines in current use.

Title: Risk of SARS-CoV-2 infection from contaminated water systems Content: Following the outbreak of severe acute respiratory syndrome coronavirus (SARS-CoV-2) in China, airborne water droplets (aerosols) have been identified as the main transmission route, although other transmission routes are likely to exist. We quantify SARS-CoV-2 virus survivability within water and the risk of infection posed by faecal contaminated water within 39 countries. We identify that the virus can remain stable within water for up to 25 days, and country specific relative risk of infection posed by faecal contaminated water is related to the environment. Faecal contaminated rivers, waterways and water systems within countries with high infection rates can provide infectious doses >100 copies within 100 ml of water. The implications for freshwater systems, the coastal marine environment and virus resurgence are discussed.

Title: Relative contributions of transmission routes for COVID-19 among healthcare personnel providing patient care. Content: The routes of COVID-19 transmission to healthcare personnel from infected patients is the subject of debate, but is critical to the selection of personal protective equipment. The objective of this paper was to explore the contributions of three transmission routes-contact, droplet, and inhalation-to the risk of occupationally acquired COVID-19 infection among healthcare personnel (HCP). The method was quantitative microbial risk assessment, and an exposure model, where possible model parameters were based on data specific to the SARS-CoV-2 virus when available. The key finding was that droplet and inhalation transmission routes predominate over the contact route, contributing 35%, 57%, and 8.2% of the probability of infection, on average, without use of personal protective equipment. On average, 80% of inhalation exposure occurs when HCP are near patients. The relative contribution of droplet and inhalation depends upon the emission of SARS-CoV-2 in respirable particles (<10 µm) through exhaled breath, and inhalation becomes predominant, on average, when emission exceeds five gene copies per min. The predicted concentration of SARS-CoV-2 in the air of the patient room is low (< 1 gene copy per m3 on average), and likely below the limit of quantification for many air sampling methods. The findings demonstrate the value of respiratory protection for HCP, and that field sampling may not be sensitive enough to verify the contribution of SARS-CoV-2 inhalation to the risk of occupationally acquired COVID-19 infection among healthcare personnel. The emission and infectivity of SARS-CoV-2 in respiratory droplets of different sizes is a critical knowledge gap for understanding and controlling COVID-19 transmission.

Title: Relative contributions of transmission routes for COVID-19 among healthcare personnel providing patient care Content: The routes of COVID-19 transmission to healthcare personnel from infected patients is the subject of debate, but is critical to the selection of personal protective equipment. The objective of this paper was to explore the contributions of three transmission routes-contact, droplet, and inhalation-to the risk of occupationally acquired COVID-19 infection among healthcare personnel (HCP). The method was quantitative microbial risk assessment, and an exposure model, where possible model parameters were based on data specific to the SARS-CoV-2 virus when available. The key finding was that droplet and inhalation transmission routes predominate over the contact route, contributing 35%, 57%, and 8.2% of the probability of infection, on average, without use of personal protective equipment. On average, 80% of inhalation exposure occurs when HCP are near patients. The relative contribution of droplet and inhalation depends upon the emission of SARS-CoV-2 in respirable particles (<10 µm) through exhaled breath, and inhalation becomes predominant, on average, when emission exceeds five gene copies per min. The predicted concentration of SARS-CoV-2 in the air of the patient room is low (< 1 gene copy per m3 on average), and likely below the limit of quantification for many air sampling methods. The findings demonstrate the value of respiratory protection for HCP, and that field sampling may not be sensitive enough to verify the contribution of SARS-CoV-2 inhalation to the risk of occupationally acquired COVID-19 infection among healthcare personnel. The emission and infectivity of SARS-CoV-2 in respiratory droplets of different sizes is a critical knowledge gap for understanding and controlling COVID-19 transmission.

Title: Identifying airborne transmission as the dominant route for the spread of COVID-19 Content: Various mitigation measures have been implemented to fight the coronavirus disease 2019 (COVID-19) pandemic, including widely adopted social distancing and mandated face covering. However, assessing the effectiveness of those intervention practices hinges on the understanding of virus transmission, which remains uncertain. Here we show that airborne transmission is highly virulent and represents the dominant route to spread the disease. By analyzing the trend and mitigation measures in Wuhan, China, Italy, and New York City, from January 23 to May 9, 2020, we illustrate that the impacts of mitigation measures are discernable from the trends of the pandemic. Our analysis reveals that the difference with and without mandated face covering represents the determinant in shaping the pandemic trends in the three epicenters. This protective measure alone significantly reduced the number of infections, that is, by over 78,000 in Italy from April 6 to May 9 and over 66,000 in New York City from April 17 to May 9. Other mitigation measures, such as social distancing implemented in the United States, are insufficient by themselves in protecting the public. We conclude that wearing of face masks in public corresponds to the most effective means to prevent interhuman transmission, and this inexpensive practice, in conjunction with simultaneous social distancing, quarantine, and contact tracing, represents the most likely fighting opportunity to stop the COVID-19 pandemic. Our work also highlights the fact that sound science is essential in decision-making for the current and future public health pandemics.

Title: Toxoplasma gondii: from animals to humans. Content: Toxoplasmosis is one of the more common parasitic zoonoses world-wide. Its causative agent, Toxoplasma gondii, is a facultatively heteroxenous, polyxenous protozoon that has developed several potential routes of transmission within and between different host species. If first contracted during pregnancy, T. gondii may be transmitted vertically by tachyzoites that are passed to the foetus via the placenta. Horizontal transmission of T. gondii may involve three life-cycle stages, i.e. ingesting infectious oocysts from the environment or ingesting tissue cysts or tachyzoites which are contained in meat or primary offal (viscera) of many different animals. Transmission may also occur via tachyzoites contained in blood products, tissue transplants, or unpasteurised milk. However, it is not known which of these routes is more important epidemiologically. In the past, the consumption of raw or undercooked meat, in particular of pigs and sheep, has been regarded as a major route of transmission to humans. However, recent studies showed that the prevalence of T. gondii in meat-producing animals decreased considerably over the past 20 years in areas with intensive farm management. For example, in several countries of the European Union prevalences of T. gondii in fattening pigs are now <1%. Considering these data it is unlikely that pork is still a major source of infection for humans in these countries. However, it is likely that the major routes of transmission are different in human populations with differences in culture and eating habits. In the Americas, recent outbreaks of acute toxoplasmosis in humans have been associated with oocyst contamination of the environment. Therefore, future epidemiological studies on T. gondii infections should consider the role of oocysts as potential sources of infection for humans, and methods to monitor these are currently being developed. This review presents recent epidemiological data on T. gondii, hypotheses on the major routes of transmission to humans in different populations, and preventive measures that may reduce the risk of contracting a primary infection during pregnancy.

Title: How does the outbreak of 2019-nCoV spread in mainland China? A retrospective analysis of the dynamic transmission routes Content: The fourth outbreak of the Coronaviruses, known as the 2019-nCoV, has occurred in Wuhan city of Hubei province in China in December 2019. We propose a time-varying sparse vector autoregressive (VAR) model to retrospectively analyze and visualize the dyamic transmission routes of this outbreak in mainland China over January 31 - February 19, 2020. Our results demonstrate that the influential inter-province routes from Hubei have become unidentifiable since February 4, whereas the self-transmission in each province was accelerating over February 4-15. From February 16, all routes became less detectable, and no influential transmissions could be identified on February 18 and 19. Such evidence supports the effectiveness of government interventions, including the travel restrictions in Hubei. Implications of our results suggest that in addition to the origin of the outbreak, virus preventions are of crucial importance in provinces with the largest migrant workers percentages (e.g., Jiangxi, Henan and Anhui) to controlling the spread of 2019-nCoV.

Title: Evidence for gastrointestinal infection of SARS-CoV-2 Content: The new coronavirus (SARS-CoV-2) outbreak originating from Wuhan, China, poses a threat to global health. While it's evident that the virus invades respiratory tract and transmits from human to human through airway, other viral tropisms and transmission routes remain unknown. We tested viral RNA in stool from 73 SARS-CoV-2-infected hospitalized patients using rRT-PCR. 53.42% of the patients tested positive in stool. 23.29% of the patients remained positive in feces even after the viral RNA decreased to undetectable level in respiratory tract. The viral RNA was also detected in gastrointestinal tissues. Furthermore, gastric, duodenal and rectal epithelia showed positive immunofluorescent staining of viral host receptor ACE2 and viral nucleocapsid protein in a case of SARS-CoV-2 infection. Our results provide evidence for gastrointestinal infection of SARS-CoV-2, highlighting its potential fecal-oral transmission route.

Title: Chapter 3 Routes of Transmission in the Food Chain Content: Abstract More than 250 different foodborne diseases have been described to date, annually affecting about one-third of the world's population. The incidence of foodborne diseases has been underreported and underestimated, and the asymptomatic presentation of some of the illnesses, worldwide heterogeneities in reporting, and the alternative transmission routes of certain pathogens are among the factors that contribute to this. Globalization, centralization of the food supply, transportation of food products progressively farther from their places of origin, and the multitude of steps where contamination may occur have made it increasingly challenging to investigate foodborne and waterborne outbreaks. Certain foodborne pathogens may be transmitted directly from animals to humans, while others are transmitted through vectors, such as insects, or through food handlers, contaminated food products or food-processing surfaces, or transfer from sponges, cloths, or utensils. Additionally, the airborne route may contribute to the transmission of certain foodborne pathogens. Complicating epidemiological investigations, multiple transmission routes have been described for some foodborne pathogens. Two types of transmission barriers, primary and secondary, have been described for foodborne pathogens, each of them providing opportunities for preventing and controlling outbreaks. Primary barriers, the most effective sites of prophylactic intervention, prevent pathogen entry into the environment, while secondary barriers prevent the multiplication and dissemination of pathogens that have already entered the environment. Understanding pathogen dynamics, monitoring transmission, and implementing preventive measures are complicated by the phenomenon of superspreading, which refers to the concept that, at the level of populations, a minority of hosts is responsible for the majority of transmission events.

Title: Influenza Virus Respiratory Infection and Transmission Following Ocular Inoculation in Ferrets Content: While influenza viruses are a common respiratory pathogen, sporadic reports of conjunctivitis following human infection demonstrates the ability of this virus to cause disease outside of the respiratory tract. The ocular surface represents both a potential site of virus replication and a portal of entry for establishment of a respiratory infection. However, the properties which govern ocular tropism of influenza viruses, the mechanisms of virus spread from ocular to respiratory tissue, and the potential differences in respiratory disease initiated from different exposure routes are poorly understood. Here, we established a ferret model of ocular inoculation to explore the development of virus pathogenicity and transmissibility following influenza virus exposure by the ocular route. We found that multiple subtypes of human and avian influenza viruses mounted a productive virus infection in the upper respiratory tract of ferrets following ocular inoculation, and were additionally detected in ocular tissue during the acute phase of infection. H5N1 viruses maintained their ability for systemic spread and lethal infection following inoculation by the ocular route. Replication-independent deposition of virus inoculum from ocular to respiratory tissue was limited to the nares and upper trachea, unlike traditional intranasal inoculation which results in virus deposition in both upper and lower respiratory tract tissues. Despite high titers of replicating transmissible seasonal viruses in the upper respiratory tract of ferrets inoculated by the ocular route, virus transmissibility to naïve contacts by respiratory droplets was reduced following ocular inoculation. These data improve our understanding of the mechanisms of virus spread following ocular exposure and highlight differences in the establishment of respiratory disease and virus transmissibility following use of different inoculation volumes and routes.

Title: Transmission Kinetics and histopathology induced by European Turkey Coronavirus during experimental infection of specific pathogen free turkeys Content: Numerous viruses, mostly in mixed infections, have been associated worldwide with poult enteritis complex (PEC). In 2008 a coronavirus (Fr‐TCoV 080385d) was isolated in France from turkey poults exhibiting clinical signs compatible with this syndrome. In the present study, the median infectious dose (ID (50))(,) transmission kinetics and pathogenicity of Fr‐TCoV were investigated in 10‐day‐old SPF turkeys. Results revealed a titre of 10(4.88) ID (50)/ml with 1 ID (50)/ml being beyond the limit of genome detection using a well‐characterized qRT‐PCR for avian coronaviruses. Horizontal transmission of the virus via the airborne route was not observed however, via the oro‐faecal route this proved to be extremely rapid (one infectious individual infecting another every 2.5 hr) and infectious virus was excreted for at least 6 weeks in several birds. Histological examination of different zones of the intestinal tract of the Fr‐TCoV‐infected turkeys showed that the virus had a preference for the lower part of the intestinal tract with an abundance of viral antigen being present in epithelial cells of the ileum, caecum and bursa of Fabricius. Viral antigen was also detected in dendritic cells, monocytes and macrophages in these areas, which may indicate a potential for Fr‐TCoV to replicate in antigen‐presenting cells. Together these results highlight the importance of good sanitary practices in turkey farms to avoid introducing minute amounts of virus that could suffice to initiate an outbreak, and the need to consider that infected individuals may still be infectious long after a clinical episode, to avoid virus dissemination through the movements of apparently recovered birds.

Title: The Ocular Surface and the Coronavirus Disease 2019: Does a Dual ‘Ocular Route’ Exist? Content: Coronavirus disease 2019 (COVID-19) is an important health problem that was defined as a pandemic by the World Health Organization on 11 March 2020. Although great concern has been expressed about COVID-19 infection acquired through ocular transmission, its underlying mechanism has not currently been clarified. In the current work, we analyzed and elucidated the two main elements that should be taken into account to understand the “ocular route”, both from a clinical and molecular point of view. They are represented by the dynamism of the ocular surface system (e.g., the tear film turnover) and the distribution of ACE2 receptors and TMPRSS2 protein. Although it seems, at the moment, that there is a low risk of coronavirus spreading through tears, it may survive for a long time or replicate in the conjunctiva, even in absence of conjunctivitis signs, indicating that eye protection (e.g., protective goggles alone or in association with face shield) is advisable to prevent contamination from external droplets and aerosol.

Title: A letter about the airborne transmission of sars-cov-2 based on the current evidence Content: World Health Organization has suggested that severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is transmitted through person-to-person transmission and contact with contaminated surfaces. However, rapid spread of the coronavirus disease 2019 (COVID-19) suggests other routes such as airborne transmission may be involved. A few research studies have been conducted to evaluate the potential transmission of this virus through air. Although some studies have found no evidence of airborne transmission, other more recent work is proving the presence of SARS-CoV-2 even in public places. Also, the past experiences and knowledge about the mechanisms of similar viruses such as SARS-CoV support this hypothesis. It seems that the best decision at the moment is to follow a conservative approach, and accept the hypothesis that SARS-CoV-2 is able to be transmitted through air. By this, control measures could be employed to prevent further COVID-19 infection.

Title: Digestive system involvement of novel coronavirus infection: Prevention and control infection from a gastroenterology perspective Content: An epidemic of an acute respiratory syndrome caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in Wuhan, China, now known as coronavirus disease 2019 (COVID-19), beginning in December 2019, has attracted an intense amount of attention worldwide. As the natural history and variety of clinical presentations of this disease unfolds, extrapulmonary symptoms of COVID-19 have emerged, especially in the digestive system. While the respiratory mode of transmission is well known and is probably the principal mode of transmission of this disease, a possibility of the fecal-oral route of transmission has also emerged in various case series and clinical scenarios. In this review article, we summarize four different aspects in published studies to date: (a) gastrointestinal manifestations of COVID-19; (b) microbiological and virological investigations; (c) the role of fecal-oral transmission; and (d) prevention and control of SARS-CoV-2 infection in the digestive endoscopy room. A timely understanding of the relationship between the disease and the digestive system and implementing effective preventive measures are of great importance for a favorable outcome of the disease and can help climnicians to mitigate further transmission by taking appropriate measures.

Title: Digestive system involvement of novel coronavirus infection: Prevention and control infection from a gastroenterology perspective Content: An epidemic of an acute respiratory syndrome caused by severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2) in Wuhan, China, now known as coronavirus disease 2019 (COVID‐19), beginning in December 2019, has attracted an intense amount of attention worldwide. As the natural history and variety of clinical presentations of this disease unfolds, extrapulmonary symptoms of COVID‐19 have emerged, especially in the digestive system. While the respiratory mode of transmission is well known and is probably the principal mode of transmission of this disease, a possibility of the fecal‐oral route of transmission has also emerged in various case series and clinical scenarios. In this review article, we summarize four different aspects in published studies to date: (a) gastrointestinal manifestations of COVID‐19; (b) microbiological and virological investigations; (c) the role of fecal‐oral transmission; and (d) prevention and control of SARS‐CoV‐2 infection in the digestive endoscopy room. A timely understanding of the relationship between the disease and the digestive system and implementing effective preventive measures are of great importance for a favorable outcome of the disease and can help climnicians to mitigate further transmission by taking appropriate measures.

Title: C19-TraNet: an empirical, global index-case transmission network of SARS-CoV-2 Content: Originating in Wuhan, the novel coronavirus, severe acute respiratory syndrome 2 (SARS-CoV-2), has astonished health-care systems across globe due to its rapid and simultaneous spread to the neighboring and distantly located countries. To gain the systems level understanding of the role of global transmission routes in the COVID-19 spread, in this study, we have developed the first, empirical, global, index-case transmission network of SARS-CoV-2 termed as C19-TraNet. We manually curated the travel history of country wise index-cases using government press releases, their official social media handles and online news reports to construct this C19-TraNet that is a spatio-temporal, sparse, growing network comprising of 187 nodes and 199 edges and follows a power-law degree distribution. To model the growing C19-TraNet, a novel stochastic scale free (SSF) algorithm is proposed that accounts for stochastic addition of both nodes as well as edges at each time step. A peculiar connectivity pattern in C19-TraNet is observed, characterized by a fourth degree polynomial growth curve, that significantly diverges from the average random connectivity pattern obtained from an ensemble of its 1,000 SSF realizations. Partitioning the C19-TraNet, using edge betweenness, it is found that most of the large communities are comprised of a heterogeneous mixture of countries belonging to different world regions suggesting that there are no spatial constraints on the spread of disease. This work characterizes the superspreaders that have very quickly transported the virus, through multiple transmission routes, to long range geographical locations alongwith their local neighborhoods.

Title: Ventilation in the Dental Clinic: An Effective Measure to Control Droplets and Aerosols during the Coronavirus Pandemic and Beyond. Content: Clinical and epidemiological studies suggest that human-to-human transmission of coronavirus disease 2019 (COVID-19) most frequently occurs through virus-laden respiratory droplets discharged from infected individuals while coughing and sneezing. Aerosols can act as another potential transmission route. The World Health Organisation (WHO) has advised medical personnel to consider taking 'airborne precautions'. It is important to protect dentists and patients and reduce the amount of spatter produced during dental procedures. In order to prevent airborne transmission, dental offices should be sufficiently ventilated, with great emphasis placed upon removing bioaerosols.

Title: COVID-19: Transmission, prevention, and potential therapeutic opportunities Content: The novel coronavirus disease (COVID-19) pandemic, caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), remains a global challenge. Despite intense research efforts worldwide, an effective vaccine and viable treatment options have eluded investigators. Therefore, infection prevention, early viral detection and identification of successful treatment protocols provide the best approach in controlling disease spread. In this review, current therapeutic options, preventive methods and transmission routes of COVID-19 are discussed.

Title: On-site measurement of tracer gas transmission between horizontal adjacent flats in residential building and cross-infection risk assessment Content: Abstract Airborne transmission is a main spread mode of respiratory infectious diseases, whose frequent epidemic has brought serious social burden. Identifying possible routes of the airborne transmission and predicting the potential infection risk are meaningful for infectious disease control. In the present study, an internal spread route between horizontal adjacent flats induced by air infiltration was investigated. On-site measurements were conducted, and tracer gas technique was employed. Two measurement scenarios, closed window mode and open window mode, were compared. Using the calculated air change rate and mass fraction, the cross-infection risk was estimated using the Wells–Riley model. It found that tracer gas concentrations in receptor rooms are one order lower than the source room, and the infection risks are also one order lower. Opening windows results in larger air change rate on the one hand, but higher mass fraction on the other hand. Higher mass fraction not necessarily results in higher infection risk as the pathogen concentration in the source room is reduced by the higher air change rate. In the present study, opening windows could significantly reduce the infection risk of the index room but slightly reduce the risks in receptor rooms. The mass fraction of air originated from the index room to the receptor units could be 0.28 and the relative cross-infection risk through the internal transmission route could be 9%, which are higher than the external spread through single-sided window flush. The study implicates that the horizontal transmission route induced by air infiltration should not be underestimated.

Title: Lack of Middle East Respiratory Syndrome Coronavirus Transmission in Rabbits Content: Middle East respiratory syndrome coronavirus (MERS-CoV) transmission from dromedaries to humans has resulted in major outbreaks in the Middle East. Although some other livestock animal species have been shown to be susceptible to MERS-CoV, it is not fully understood why the spread of the virus in these animal species has not been observed in the field. In this study, we used rabbits to further characterize the transmission potential of MERS-CoV. In line with the presence of MERS-CoV receptor in the rabbit nasal epithelium, high levels of viral RNA were shed from the nose following virus inoculation. However, unlike MERS-CoV-infected dromedaries, these rabbits did not develop clinical manifestations including nasal discharge and did shed only limited amounts of infectious virus from the nose. Consistently, no transmission by contact or airborne routes was observed in rabbits. Our data indicate that despite relatively high viral RNA levels produced, low levels of infectious virus are excreted in the upper respiratory tract of rabbits as compared to dromedary camels, thus resulting in a lack of viral transmission.

Title: Tropism of human adenovirus type 5-based vectors in swine and their ability to protect against transmissible gastroenteritis coronavirus. Content: The infection of epithelia] swine testicle and intestinal porcine epithelial (IPEC-1) cell lines by adenovirus type 5 (Ad5) has been studied in vitro by using an Ad5-luciferase recombinant containing the firefly luciferase gene as a reporter. Porcine cell lines supported Ad5 replication, showing virus titers, kinetics of virus production, and luciferase expression levels similar to those obtained in human 293 cells, which constitutively express the 5'-end 11% of the Ad5 genome. The tropism of Ad5-based vectors in swine and its ability to induce an efficient immune response against heterologous antigens expressed by foreign genes inserted in these vectors has been determined. Ad5 vectors replicate and express heterologous antigens in porcine lungs and mediastinal and mesenteric lymph nodes. Significant levels of heterologous antigen expression were also demonstrated in the small intestine (jejunum and ileum), but Ad5 replication in this organ was very poor, suggesting that Ad vectors undergo an abortive replication in the porcine small intestine. The tissues infected by Ad5 were dependent on the inoculation route. The oronasal route appeared to be best for inoculation of bronchus-associated lymphoid tissue infection, while the intraperitoneal route was best for gut-associated lymphoid tissue infection. Epithelial cells of bronchioles, macrophages, type II pneumocytes, and follicular dendritic cells were identified as targets for Ad5, while epithelial cells of the intestine were not infected by Ad5. Viruses with a deletion from 79.5 to 84.8 map units in the E3 region, with or without heterologous inserted genes, replicated to lower levels in porcine tissues than did wild-type Ad5. It was also shown that an Ad5 recombinant expressing the four antigenic sites (A, B, C, and D) of transmissible gastroenteritis coronavirus (TGEV) spike protein induced in swine immune responses which neutralized TGEV infectivity. In addition, porcine serum from Ad-TGEV-immune animals provide passive protection when mixed with fully virulent TGEV and orally administered to highly susceptible newborn piglets. These results taken together indicate that swine may be a good animal model for human Ad5 lung infection to aid in the evaluation of candidate adenovirus vaccines and that Ad5 may be suitable as a recombinant viral vaccine or for other applications in swine.

Title: Isolation of a porcine respiratory, non-enteric coronavirus related to transmissible gastroenteritis. Content: A porcine respiratory, non-enteric virus which is related to the coronavirus transmissible gastroenteritis virus (TGEV) has been isolated in pigs and in cell culture. The isolate was designated TLM 83. It has become very widespread and enzootic among the swine population in Belgium and in other swine raising countries. It causes an infection of the lungs and appears to spread by aerogenic route. It does not replicate in the enteric tract. The experimental infection in conventional and gnotobiotic pigs in isolation remains subclinical. The infection, either experimental or in the field, results in the formation of antibodies which neutralise the classical enteric TGEV. Based on this relationship, this virus is assumed to be a new TGEV-related porcine respiratory coronavirus or TGEV itself which has totally lost its tropism for the enteric tract.

Title: [Replication and transmission mechanisms of highly pathogenic human coronaviruses] Content: The three known human highly pathogenic coronaviruses are severe acute respiratory syndrome coronavirus (SARS-CoV), Middle East respiratory syndrome coronavirus, (MERS-CoV), and severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) Human highly pathogenic coronaviruses are composed of non-structural proteins, structural proteins and accessory proteins Viral particles recognize host receptors via spike glycoprotein (S protein), enter host cells by membrane fusion, replicate in host cells through large replication-transcription complexes, and promote proliferation by interfering with and suppressing the host's immune response Human highly pathogenic coronaviruses are hosted by humans and vertebrates Viral particles are transmitted through droplets, contact and aerosols or likely through digestive tract, urine, eyes and other routes This review discusses the mechanisms of proliferation and transmission of highly pathogenic human coronaviruses based on the results of existing research, providing basis for future study on interrupting the transmission and pathogenicity of human highly pathogenic coronaviruses

Title: [Replication and transmission mechanisms of highly pathogenic human coronaviruses]. Content: The three known human highly pathogenic coronaviruses are severe acute respiratory syndrome coronavirus (SARS-CoV), Middle East respiratory syndrome coronavirus, (MERS-CoV), and severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Human highly pathogenic coronaviruses are composed of non-structural proteins, structural proteins and accessory proteins. Viral particles recognize host receptors via spike glycoprotein (S protein), enter host cells by membrane fusion, replicate in host cells through large replication-transcription complexes, and promote proliferation by interfering with and suppressing the host's immune response. Human highly pathogenic coronaviruses are hosted by humans and vertebrates. Viral particles are transmitted through droplets, contact and aerosols or likely through digestive tract, urine, eyes and other routes. This review discusses the mechanisms of proliferation and transmission of highly pathogenic human coronaviruses based on the results of existing research, providing basis for future study on interrupting the transmission and pathogenicity of human highly pathogenic coronaviruses.

Title: Epidemiology of coronavirus disease 2019(COVID-19) caused by SARS-CoV-2 Content: In December, 2019, an infection outbreak occurred in Wuhan of unknown cause, which attracts intense attention. Shortly after the virus was identified with the name of severe acute respiratory syndrome coronavirus 2(SARS-CoV-2), the epidemic of coronavirus disease 2019 (COVID-19) broke out and an information storm occurred. At that time, two important aspects: the stage and the links of epidemic, were unclear. Answers to the questions, what are the sources, how do infections occur, and who will be affected should be clarified as the outbreak continues to evolve. Furthermore, the epidemic process and the stage of epidemic should be explored and discussed. Based on information of SARS, middle east respiratory syndrome(MERS) and COVID-19, the links of epidemic (the sources, the routes of infection, and the susceptible population) will be discussed as well as the role of the natural and the social factors. Epidemiology characteristics of patients will be traced based on current information.

Title: Epidemiology of coronavirus disease 2019(COVID-19) caused by SARS-CoV-2. Content: In December, 2019, an infection outbreak occurred in Wuhan of unknown cause, which attracts intense attention. Shortly after the virus was identified with the name of severe acute respiratory syndrome coronavirus 2(SARS-CoV-2), the epidemic of coronavirus disease 2019 (COVID-19) broke out and an information storm occurred. At that time, two important aspects: the stage and the links of epidemic, were unclear. Answers to the questions, what are the sources, how do infections occur, and who will be affected should be clarified as the outbreak continues to evolve. Furthermore, the epidemic process and the stage of epidemic should be explored and discussed. Based on information of SARS, middle east respiratory syndrome(MERS) and COVID-19, the links of epidemic (the sources, the routes of infection, and the susceptible population) will be discussed as well as the role of the natural and the social factors. Epidemiology characteristics of patients will be traced based on current information.

Title: Ocular conjunctival inoculation of SARS-CoV-2 can cause mild COVID-19 in Rhesus macaques Content: The outbreak of Corona Virus Disease 2019 caused by the severe acute respiratory syndrome coronavirus (SARS-CoV-2) is highly transmitted. The potential extra-respiratory transmission routes remain uncertain. Five rhesus macaques were inoculated with 1×106 TCID50 of SARS-CoV-2 via conjunctival (CJ), intratracheal (IT), and intragastric (IG) routes, respectively. Remarkably, the CJ inoculated-macaques developed mild interstitial pneumonia and viral load was detectable in the conjunctival swabs at 1 days post-inoculation (dpi). Only via IT inoculation, viral load was detected in the anal swab at 1-7 dpi and macaque showed weight loss. However, viral load was undetectable after IG inoculation. Comparatively, viral load was higher in the nasolacrimal system but lesions of lung were relatively mild and local via CJ inoculation compared with that via IT inoculation, demonstrating distinct characteristics of virus dispersion. Both the two routes affected the alimentary tract. Therefore the clinicians need to protect eye while working with patients.

Title: The 2019 novel coronavirus disease (COVID-19) pandemic: A zoonotic prospective Content: Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), a novel coronavirus (CoV), has recently emerged as a significant pathogen for humans and the cause for the recent outbreak of the 2019 novel coronavirus disease (COVID-19) throughout the globe For developing any preventive measure, an understanding of the zoonotic pattern for this virus is a necessity We should have a clear knowledge of its reservoir host, its distribution pattern and spreading routes Information about zoonotic reservoirs and its transmission among them can help to understand the COVID-19 outbreaks In this article, we discuss about the bats as the zoonotic reservoir of several CoV strains, co-existence of bats and CoV/viruses, the sequence similarity of SARS-CoV-2 with bat SARS-like CoV, the probable source of the origin of SARS-CoV-2 strain and COVID-19 outbreak, intermediate host of CoVs and SARS-CoV-2, human to human transmission and the possibility to maintain the zoonotic barriers Our knowledge about the zoonotic reservoir of SARS-CoV-2 and its transmission ability may help develop the preventive measures and control for the future outbreak of CoV

Title: Mask use during COVID-19: A risk adjusted strategy Content: In the context of Coronavirus Disease (2019) (COVID-19) cases globally, there is a lack of consensus across cultures on whether wearing face masks is an effective physical intervention against disease transmission. This study 1) illustrates transmission routes of Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2); 2) addresses controversies surrounding the mask from perspectives of attitude, effectiveness, and necessity of wearing the mask with evidence that the use of mask would effectively interrupt the transmission of infectious diseases in both hospital settings and community settings; and 3) provides suggestion that the public should wear the mask during COVID-19 pandemic according to local context. To achieve this goal, government should establish a risk adjusted strategy of mask use to scientifically publicize the use of masks, guarantee sufficient supply of masks, and cooperate for reducing health resources inequities.

Title: Mask use during COVID-19: A risk adjusted strategy() Content: In the context of Coronavirus Disease (2019) (COVID-19) cases globally, there is a lack of consensus across cultures on whether wearing face masks is an effective physical intervention against disease transmission. This study 1) illustrates transmission routes of Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2); 2) addresses controversies surrounding the mask from perspectives of attitude, effectiveness, and necessity of wearing the mask with evidence that the use of mask would effectively interrupt the transmission of infectious diseases in both hospital settings and community settings; and 3) provides suggestion that the public should wear the mask during COVID-19 pandemic according to local context. To achieve this goal, government should establish a risk adjusted strategy of mask use to scientifically publicize the use of masks, guarantee sufficient supply of masks, and cooperate for reducing health resources inequities.

Title: Prevention and control of COVID-19 in nursing homes, orphanages, and prisons Content: As the number of Coronavirus Disease (2019) (COVID-19) cases increase globally, countries are taking more aggressive preventive measures against this pandemic. Transmission routes of Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) include droplet and contact transmissions. There are also evidence of transmission through aerosol generating procedures (AGP) in specific circumstances and settings. Institutionalized populations without mobility and living in close proximity with unavoidable contact are especially vulnerable to higher risks of COVID-19 infection, such as the elderly in nursing homes, children in orphanages, and inmates in prisons. In these places, higher prevention and control measures are needed. In this study, we proposed prevention and control strategies for these facilities and provided practical guidance for general measures, health management, personal protection measures, and prevention measures in nursing homes, orphanages, and prisons, respectively.

Title: Middle East respiratory syndrome coronavirus (MERS-CoV) in dromedary camels, Oman, 2013. Content: A countrywide survey in Oman revealed Middle Eastrespiratory syndrome coronavirus (MERS-CoV) nucleicacid in five of 76 dromedary camels. Camel-derivedMERS-CoV sequences (3,754 nucleotides assembled from partial sequences of the open reading frame (ORF)1a, spike, and ORF4b genes) from Oman and Qatar were slightly different from each other, but closely related to human MERS-CoV sequences from the same geographical areas, suggesting local zoonotic transmission. High viral loads in nasal and conjunctival swabs suggest possible transmission by the respiratory route.

Title: Uncertainties about the transmission routes of 2019 novel coronavirus Content:

Title: Family cluster of three recovered cases of pneumonia due to severe acute respiratory syndrome coronavirus 2 infection Content: The coronavirus disease (COVID-19) outbreak caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) was first reported in Wuhan, China, in late 2019 and has affected more than 1 270 000 people worldwide. The numbers of reported cases continue to rise and threaten global health. Transmissions among family members are frequently observed, although the route of transmission is partially known. Here we report three cases of SARS-CoV-2 infection within one family. Sequencing of the S gene of the viral genome showed 100% identity among samples, suggesting that the same strain caused the infection. Following treatment with oseltamivir and short-term methylprednisolone combined with symptomatic management, all three patients recovered within 3 weeks, as evidenced by the disappearance of their symptoms, clearance of pulmonary infiltrates and consecutive negative molecular diagnostic test findings. Our observations suggest the importance of preventing family transmission and the efficacy of current integrated treatment for mild/moderate pneumonia in COVID-19 cases.

Title: Human intestinal tract serves as an alternative infection route for Middle East respiratory syndrome coronavirus Content: Middle East respiratory syndrome coronavirus (MERS-CoV) has caused human respiratory infections with a high case fatality rate since 2012. However, the mode of virus transmission is not well understood. The findings of epidemiological and virological studies prompted us to hypothesize that the human gastrointestinal tract could serve as an alternative route to acquire MERS-CoV infection. We demonstrated that human primary intestinal epithelial cells, small intestine explants, and intestinal organoids were highly susceptible to MERS-CoV and can sustain robust viral replication. We also identified the evidence of enteric MERS-CoV infection in the stool specimen of a clinical patient. MERS-CoV was considerably resistant to fed-state gastrointestinal fluids but less tolerant to highly acidic fasted-state gastric fluid. In polarized Caco-2 cells cultured in Transwell inserts, apical MERS-CoV inoculation was more effective in establishing infection than basolateral inoculation. Notably, direct intragastric inoculation of MERS-CoV caused a lethal infection in human DPP4 transgenic mice. Histological examination revealed MERS-CoV enteric infection in all inoculated mice, as shown by the presence of virus-positive cells, progressive inflammation, and epithelial degeneration in small intestines, which were exaggerated in the mice pretreated with the proton pump inhibitor pantoprazole. With the progression of the enteric infection, inflammation, virus-positive cells, and live viruses emerged in the lung tissues, indicating the development of sequential respiratory infection. Taken together, these data suggest that the human intestinal tract may serve as an alternative infection route for MERS-CoV.

Title: Implication of COVID‐19 in oral oncology practices in Brazil, Canada and the United States Content: The newly emerged Coronavirus disease 2019 (COVID‐19) is an infectious disease that has spread rapidly throughout the world. The most common signs and symptoms are fever, dry cough and shortness of breath which can progress to severe viral pneumonia and multi‐organ failure in susceptive patients (Chen et al. 2020, Wang et al. 2020). Droplet transmission and person‐person transmission appear to be the main route of transmission of COVID‐19, however asymptomatic patients are also carriers of the virus (Rothe et al. 2020).

Title: Ophthalmologic evidence against the interpersonal transmission of 2019 novel coronavirus through conjunctiva Content: Background: The emerging 2019 novel coronavirus (2019-nCoV) has pushed several countries into state of emergency all over the world. The possible transmission of 2019-nCoV by conjunctiva is controversial and has substantial public health implications. Methods: A retrospective cohort study was initiated to investigate the possible transmission of 2019-nCoV through aerosol contact with conjunctiva. We enrolled 67 cases of confirmed or suspected cases of novel coronavirus pneumonia (NCP) during 17-28 Jan 2020. Nasopharyngeal and conjunctival swabs were collected for real time RT-PCR analysis to detect 2019-nCoV. Results: 63 patients were identified as laboratory-confirmed NCP and the remaining four were suspected NCP. Conjunctival swab samples from one NCP patient yielded positive PCR results and two NCP patients yielded probable positive PCR results. None of the three patients had ocular symptoms. The only one NCP patient with conjunctivitis as the first symptom had negative conjunctival sac 2019-nCoV test. Conjunctival swab samples from the four suspected cases of NCIP were negative. Conclusion: 2019-nCoV can be detected in the conjunctival sac of patients with NCP. Through clinical analysis, viral transmission via the conjunctival route was not supported by the data. Good clinical protection can effectively cut off the transmission path.

Title: [Preliminary result on the nosocomial infection of severe acute respiratory syndrome in one hospital of Beijing]. Content: OBJECTIVE To study the transmission route of severe acute respiratory syndrome (SARS) nosocomial infection. METHODS Ten identified SARS patients were selected from a general hospital in March. Survey was carried out through a standardized questionnaire provided by Chinese Center for Disease Control and Prevention. Contents of the questionnaire would include: history of contact with SARS patient, route of infection, methods used for protection and so on. RESULTS (1) Distribution os SARS patients were confined to 3 wards: 4, 5, and 6 on the 7, 8, 12, 13 and 14 floors in the west unit of the inpatient building. Most of the inpatients were elderly and having severe original diseases. (2) Index patients were the first generation source of transmission and they infected inpatients and medical staff, making them the second generation. People with latent infection who had close contact with SARS patients might also serve as the possible source of transmission. (3) The major transmission routes were: near distant droplet infection and close contact infection. There was also a clue to the probability of aerosol or droplet nuclei infection through air-conditioning and ventilation system. CONCLUSION Nosocomial infection appeared to be the main characteristic of the SARS epidemic in the early stage of this hospital. Other than close contact and near space airborne transmission of SARS virus, the possibility of long-distance aerosol transmission called for further epidemiological and experimental studies in the future.

Title: Stability of bovine coronavirus on lettuce surfaces under household refrigeration conditions Content: Fecal suspensions with an aerosol route of transmission were responsible for a cluster of severe acute respiratory syndrome (SARS) cases in 2003 in Hong Kong. Based on that event, the World Health Organization recommended that research be implemented to define modes of transmission of SARS coronavirus through sewage, feces, food and water. Environmental studies have shown that animal coronaviruses remain infectious in water and sewage for up to a year depending on the temperature and humidity. In this study, we examined coronavirus stability on lettuce surfaces. A cell culture adapted bovine coronavirus, diluted in growth media or in bovine fecal suspensions to simulate fecal contamination was used to spike romaine lettuce. qRT-PCR detected viral RNA copy number ranging from 6.6 × 10(4) to 1.7 × 10(6) throughout the experimental period of 30 days. Whereas infectious viruses were detected for at least 14 days, the amount of infectious virus varied, depending upon the diluent used for spiking the lettuce. UV and confocal microscopic observation indicated attachment of residual labeled virions to the lettuce surface after the elution procedure, suggesting that rates of inactivation or detection of the virus may be underestimated. Thus, it is possible that contaminated vegetables may be potential vehicles for coronavirus zoonotic transmission to humans.

Title: Coronavirus (COVID-19) outbreak: what the department of endoscopy should know Content: Italy recorded its first case of confirmed acute respiratory illness because of coronavirus on February 18, 2020, soon after the initial reports in China. Since that time, Italy and nations throughout the world have adopted very stringent and severe measures to protect populations from spread of infection. Despite these measures, the number of infected people is growing exponentially, with a significant number of patients developing acute respiratory insufficiency. Endoscopy departments face significant risk for diffusion of respiratory diseases that can be spread via an airborne route, including aspiration of oral and fecal material via endoscopes. The purpose of this article is to discuss the measures, with specific focus on personal protection equipment and dress code modalities, implemented in our hospital to prevent further dissemination of COVID-19 infection.

Title: Early events during human coronavirus OC43 entry to the cell Content: The Coronaviridae family clusters a number of large RNA viruses, which share several structural and functional features. However, members of this family recognize different cellular receptors and exploit different entry routes, what affects their species specificity and virulence. The aim of this study was to determine how human coronavirus OC43 enters the susceptible cell. Using confocal microscopy and molecular biology tools we visualized early events during infection. We found that the virus employs caveolin-1 dependent endocytosis for the entry and the scission of virus-containing vesicles from the cell surface is dynamin-dependent. Furthermore, the vesicle internalization process requires actin cytoskeleton rearrangements. With our research we strove to broaden the understanding of the infection process, which in future may be beneficial for the development of a potential therapeutics.

Title: Role of viral bioaerosols in nosocomial infections and measures for prevention and control Content: Abstract The presence of patients with diverse pathologies in hospitals results in an environment that can be rich in various microorganisms including respiratory and enteric viruses, leading to outbreaks in hospitals or spillover infections to the community. All hospital patients are at risk of nosocomial viral infections, but vulnerable groups such as older adults, children and immuno-compromised/-suppressed patients are at particular risk of severe outcomes including prolonged hospitalization or death. These pathogens could transmit through direct or indirect physical contact, droplets or aerosols, with increasing evidence suggesting the importance of aerosol transmission in nosocomial infections of respiratory and enteric viruses. Factors affecting the propensity to transmit and the severity of disease transmitted via the aerosol route include the biological characteristics affecting infectivity of the viruses and susceptibility of the host, the physical properties of aerosol particles, and the environmental stresses that alter these properties such as temperature and humidity. Non-specific systematic and individual-based interventions designed to mitigate the aerosol route are available although empirical evidence of their effectiveness in controlling transmission of respiratory and enteric viruses in healthcare settings are sparse. The relative importance of aerosol transmission in healthcare setting is still an on-going debate, with particular challenge being the recovery of infectious viral bioaerosols from real-life settings and the difficulty in delineating transmission events that may also be a result of other modes of transmission. For the prevention and control of nosocomial infections via the aerosol route, more research is needed on identifying settings, medical procedures or equipment that may be associated with an increased risk of aerosol transmission, including defining which procedures are aerosol-generating; and on the effectiveness of systematic interventions on aerosol transmission of respiratory and enteric viruses in healthcare settings.

Title: Emergence of COVID-19 Infection: What Is Known and What Is to Be Expected-Narrative Review Article Content: BACKGROUND: The discovery of the coronavirus disease 2019 (COVID-19) during a pneumonia outbreak in Wuhan city (China) has raised a global public health concern, as the city consists of around 11 million people and is considered a major transport and logistics hub. This deadly virus caused the world to be in high alert as the death toll and the number of confirmed cases is continuously rising since the first case was reported. The Chinese government warned that the transmission ability of the virus is increasing, and international efforts are needed to overcome this outbreak. The purpose of this review is to focus on the published articles about the new virus, which will give an insight into the current state of research and data available, as well as recommending future studies. METHODS: For this narrative review, more than 20 relevant scientific articles and reports were considered from various databases (e.g., Google Scholar, PubMed and Science Direct) using keywords such as Coronavirus Outbreak, COVID-19, Emerging Epidemics, Emerging Infections, and Novel Coronavirus. RESULTS: The results from this review show that the situation is rapidly evolving, as human-to-human transmission is occurring, and the number of new cases and mortalities is increasing by the day and on a global level. There is still ambiguity about mutation risks and how the virus spreads as the source was not yet identified. Major gaps in knowledge about the origin of the virus, epidemiology and transmission impose a great challenge, which emphasizes the need for further studies in the future.

Title: The presence of SARS-CoV-2 RNA in the feces of COVID-19 patients Content: In December 2019, coronavirus disease 2019 (COVID-19), caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), emerged in Wuhan, China, and has spread globally. However, the transmission route of SARS-CoV-2 has not been fully understood. In this study, we aimed to investigate SARS-CoV-2 shedding in the excreta of COVID-19 patients. Electronical medical records, including demographics, clinical characteristics, laboratory and radiological findings of enrolled patients were extracted and analyzed. Pharyngeal swab, stool, and urine specimens were collected and tested for SARS-CoV-2 RNA by real-time reverse transcription polymerase chain reaction. Viral shedding at multiple time points in specimens was recorded, and its correlation analyzed with clinical manifestations and the severity of illness. A total of 42 laboratory-confirmed patients were enrolled, 8 (19.05%) of whom had gastrointestinal symptoms. A total of 28 (66.67%) patients tested positive for SARS-CoV-2 RNA in stool specimens, and this was not associated with the presence of gastrointestinal symptoms and the severity of illness. Among them, 18 (64.29%) patients remained positive for viral RNA in the feces after the pharyngeal swabs turned negative. The duration of viral shedding from the feces after negative conversion in pharyngeal swabs was 7 (6-10) days, regardless of COVID-19 severity. The demographics, clinical characteristics, laboratory and radiologic findings did not differ between patients who tested positive and negative for SARS-CoV-2 RNA in the feces. Viral RNA was not detectable in urine specimens from 10 patients. Our results demonstrated the presence of SARS-CoV-2 RNA in the feces of COVID-19 patients and suggested the possibility of SARS-CoV-2 transmission via the fecal-oral route.