DOI: 10.14744/ejmo.2020.12220
EJMO 2020;4(1):1–7

Review2019 Novel Coronavirus (COVID-19) Outbreak:
A Review of the Current Literature
Ahmet Riza Sahin,1 Aysegul Erdogan,2 Pelin Mutlu Agaoglu,2 Yeliz Dineri,2Mahmut Egemen Senel,3 Ramazan Azim Okyay2, Ali Muhittin Tasdogan4

Ahmet Yusuf Cakirci,2 		

Department of Infectious Diseases and Clinical Microbiology, Kahramanmaras Sutcu Imam University Faculty of Medicine,
Kahramanmaras, Turkey
2
Department of Public Health, Kahramanmaras Sutcu Imam University Faculty of Medicine, Kahramanmaras, Turkey
3
Department of Internal Medicine, Kahramanmaras Sutcu Imam University Faculty of Medicine, Kahramanmaras, Turkey
4
Department of Anesthesiology and Reanimation, Hasan Kalyoncu University Health Sciences Faculty, Gaziantep, Turkey
1

Abstract
Coronaviruses (CoV) belong to the genus Coronavirus with its high mutation rate in the Coronaviridae.
The objective of this review article was to have a preliminary opinion about the disease, the ways of treatment, andprevention in this early stage of COVID-19 outbreak.
Keywords: COVID-19, Coronaviruses, outbreak
Cite This Article: Sahin AR, Erdogan A, Mutlu Agaoglu P, Dineri Y, Cakirci AY, Senel ME, et al. 2019 Novel Coronavirus (COVID-19) Outbreak: A Review of the Current Literature. EJMO 2020;4(1):1-7.

C

oronaviruses (CoV) belong to the genus Coronavirus
in the Coronaviridae. All CoVs are pleomorphic RNA viruses characteristically containing crown-shape peplomers
with 80-160 nM in size and 27-32 kb positive polarity. Recombination rates of CoVs are very high because of constantly developing transcription errors and RNA Dependent RNA Polymerase (RdRP) jumps. With its high mutation
rate, Coronaviruses are zoonotic pathogens that are present in humans and various animals with a wide range ofclinical features from asymptomatic course to requirementof hospitalization in the intensive care unit; causing infections in respiratory, gastrointestinal, hepatic and neurologic systems.[1-3] They were not considered as highly pathogenic for humans until they have been seen with the severe
acute respiratory syndrome (SARS) in the Guangdong stateof China for the first time in 2002 and 2003. Before theseoutbreaks, there were the two most known types of CoV
as CoV OC43 and CoV 229E that have mostly caused mild
infections in people with an adequate immune system.[3, 4]
Approximately ten years after SARS this time, another highly pathogenic CoV, Middle East Respiratory Syndrome Coronavirus (MERS-CoV) has emerged in the Middle East countries.[5] In December 2019, 2019 novel Coronavirus (nCoV),
which is another public health problem, has emerged in
the Huanan Seafood Market, where livestock animals arealso traded, in Wuhan State of Hubei Province in China andhas been the focus of global attention due to a pneumonia epidemic of unknown cause.[6] At first, an unknown
pneumonia case was detected on December 12, 2019,and possible influenza and other coronaviruses were ruled

Address for correspondence: Ahmet Riza Sahin, MD. Kahramanmaras Sutcu Imam Universitesi Tip Fakultesi,
Enfeksiyon Hastaliklari ve Klinik Mikrobiyoloji Anabilim Dali, Kahramanmaras, Turkey
Phone: +90 505 541 37 65 E-mail: drahmet_riza@hotmail.com
Submitted Date: February 11, 2020 Accepted Date: February 12, 2020 Available Online Date: Fabruary 12, 2020©
Copyright 2020 by Eurasian Journal of Medicine and Oncology - Available online at www.ejmo.org
OPEN ACCESS This work is licensed under a Creative Commons Attribution-NonCommercial 4.0 International License.

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Sahin et al., 2019 Novel Coronavirus (COVID-19) Outbreak / doi: 10.14744/ejmo.2020.12220

out by laboratory testing. Chinese authorities announced
on January 7, 2020 that a new type of Coronavirus (novel
Coronavirus, nCoV) was isolated.[7] This virus was named as
Novel Coronavirus WHO on January 12 and COVID-19 on
11 February 2020. As of February 12, 2020, a total of 43.103
confirmed cases and 1.018 deaths have been announced.
[8]
When given where the first case originated, the infection
were transmitted probably as zoonotic agent (from animal
to human). The increase in the number of cases in Wuhan
city and internationally after closing the market and evacuation of the cases in China, has indicated a second transmission from human-to-human. New cases are identified,primarily in other Asian countries and in many countries
such as the trans-oceanic USA and France (Table 1).
The objective of this review article was to have a preliminary opinion about the disease, the ways of treatment, andprevention in this early stage of this outbreak.

Epidemiology
In December 2019, many pneumonia cases that were clustered in Wuhan city were reported and searches for thesource have shown Huanan Seafood Market as the origin.
The first case of the COVID-19 epidemic was discovered
with unexplained pneumonia on December 12, 2019, and27 viral pneumonia cases with seven being severe, were officially announced on December 31, 2019.[7,9] Etiologic investigations have been performed in patients who applied
to the hospital due to similar viral pneumonia findings. The
common history of high-risk animal contact in the medical histories of these patients has strengthened the likeliTable 1. The Number of Cases and Death of COVID-19 outbreak according to World Health Organization (WHO) Situation
Reports-22 on February 11, 2020[9]Country

Cases

DeathsRegionChina
Singapore
Hong Kong
ThailandSouth Korea
Japan
Malaysia
Germany
Australia
VietnamUnited States
FranceMacao
United Kingdom
United Arab Emirates

42.708
45
42
33
28
26
18
16
15
15
13
11
10
8
8

1.017
0
1
0
0
0
0
0
0
0
0
0
0
0
0

Asia
Asia
Asia
Asia
Asia
Asia
Asia
EuropeAustralia
Australia
North America
EuropeAsia
EuropeAsiahood of an infection transmitted from animals to humans.
On January 22, 2020, novel CoV has been declared to
be originated from wild bats and belonged to Group 2 ofbeta-coronavirus that contains Severe Acute Respiratory
Syndrome Associated Coronavirus (SARS-CoV). Although
COVID-19 and SARS-CoV belong to the same beta coronavirüs subgroup, similarity at genome level is only 70%, andthe novel group has been found to show genetic differences from SARS-CoV.[10][3, 9]

Similar to the SARS epidemic, this outbreak has occurred
during the Spring Festival in China, which is the most famous traditional festival in China, during which nearly 3
billion people travel countrywide. These conditions caused
favorable conditions for the transmission of this highly contagious disease and severe difficulties in prevention andcontrol of the epidemic. The period of the Spring Festival
of China was between January 17 and February 23 in 2003,
when the SARS epidemic peaked, while the period of thefestival was between January 10 and February 18 in 2020.
Similarly, there was a rapid increase in COVID-19 cases between January 10-22. Wuhan, the center of the epidemic
with 10 million population, is also an important center inthe spring festival transportation network. The estimatednumber of travelers during the 2020 spring festival has
risen 1.7 folds when compared with the number traveledin 2003 and reached to 3.11 billion from 1.82 billion. Thislarge-scale travel traffic has also created favorable conditions for the spread of this difficult-to-control disease.[11]Virology-Pathogenesis
Coronaviruses are viruses whose genome structure is best
known among all RNA viruses. Two-thirds of RNA they haveencodes viral polymerase (RdRp), RNA synthesis materials,
and two large nonstructural polyproteins that are not involved in host response modulation (ORF1a-ORF1b). The
other one-third of the genome encodes four structuralproteins (spike (S), envelope (E), membrane (M) ve nucleocapsid (N), and the other helper proteins.[12,13] Although
the length of the CoV genome shows high variability for
ORF1a/ORF1b and four structural proteins, it is mostly associated with the number and size of accessory proteins.
[12,13]
The first step in virus infection is the interaction of sensitive human cells with Spike Protein. Genome encoding
occurs after entering to the cell and facilitates the expression of the genes, that encode useful accessory proteins,which advance the adaptation of CoVs to their human host.
[13]
Genome changes resulting from recombination, geneexchange, gene insertion, or deletion are frequent among
CoVs, and this will take place in future outbreaks as in past
epidemics. As a result of the studies, the CoV subfamily is
rapidly expanding with new generation sequencing appli-

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cations that improve the detection and definition of novel
CoV species. In conclusion, CoV classification is continuallychanging. According to the most recent classification of The
International Committee on Taxonomy of Viruses (ICTV),
there are four genera of thirty-eight unique species.[14]SARS-CoV and MERS-CoV that attach to the host cell respectively bind to cellular receptor angiotensin-converting
enzyme 2 (SARS-CoV associated) and cellular receptor of dipeptidyl peptidase 4 (MERS-CoV associated).[15] After entering the cell, the viral RNA manifest itself in the cytoplasm.
Genomic RNA is encapsulated and polyadenylated, andencodes various structural and non-structural polypeptide
genes. These polyproteins are split by proteases that exhibit chymotrypsin-like activity.[13, 15] The resulting complex
drives (-) RNA production through both replication andtranscription. During replication, full-length (-) RNA copiesof the genome are produced and used as a template forfull-length (+) RNA genomes.[12, 13] During transcription, a
subset of 7-9 sub-genomic RNAs, including those encoding
all structural proteins, are produced by discontinuous transcription. Viral nucleocapsids are combined from genomic
RNA and R protein in the cytoplasm and then are budded
into the lumen of the endoplasmic reticulum. Virions arethen released from the infected cell through exocytosis.
The released viruses can infect kidney cells, liver cells, intestines, and T lymphocytes, as well as the lower respiratory tract, where they form the main symptoms and signs.
[15]
Remarkably, CDT lymphocytes were found to be lower
than 200 cells/mm3 in three patients with SARS-CoV infection. MERS-CoV is able to affect human dendritic cells andmacrophages in-vitro. T lymphocytes are also a target forthe pathogen due to the characteristic CD26 rosettes. Thisvirus can make the antiviral T-cell response irregular due tothe stimulation of T-cell apoptosis, thus causing a collapseof the immune system.[16, 17]

Sources & Modes of Transmission
CoVs have been defined as a novel respiratory tract virus
in the samples collected from the individuals who present
symptoms of respiratory tract infection in 1962.[18] This isa large family of viruses that are common in many different animal species, including camels, cattle, cats, and bats.
Rarely, animal CoVs can infect humans and, as a result, may
spread among humans during epidemics such as MERS,SARS, and COVID-19.[13-16] At the onset of major outbreaks
caused by CoVs, palm cats have been proposed to be anatural reservoir of Human CoVs for SARS and dromedarycamels for MERS.[3] However, more advanced virologicaland genetic studies have shown that bats are reservoir
hosts of both SARS-CoV and MERS-CoV and before theseviruses spread to humans, they use the other responsible

animals as intermediate hosts. Studies have reported thatmost of the bat CoVs are the gene source of alpha-CoV andbeta-CoVs, while most of the bird CoVs are the gene sourceof gamma-CoVs and delta-CoVs.[3] In recent studies, it has
been observed that the novel virus causing epidemics coincides with the CoV isolated in bats. Presence of wild animal trade in Huanan Seafoods Market where the first cases
appeared, supports this finding.[6, 10]
After the first outbreak, secondary cases began to be reported after approximately ten days. Moreover, while thesenew patients had no contact with the marketplace, they
had a history of contact with humans there. Confirmed
recent reports from many infected healthcare workers in
Wuhan show that human-to-human transmission can occur. As in SARS and MERS epidemics in the past, human-tohuman transmission has accelerated the spread of the outbreak and case reports have also started from other statesof China. The first non-Chinese case of the infection, which
spread to the Chinese provinces, and then to the Asian continent, was reported from Thailand on January 13, 2020.
The case reported being a Chinese tourist who has traveledto Thailand and had no epidemiologic connection with themarketplace.[19] Other cases from oversea countries such as
the USA and France have continued to be reported.[20]Often, the human-to-human transmission occurs with close
contact. The transmission primarily occurs when an infected
person sneezes and through the respiratory droplets produced just as the spread of influenza and other respiratory
pathogens. These droplets can settle in the mouth or nasal
mucosa and lungs of people with inhaled air. Currently, itremains unclear whether a person can be infected by COVID-19 by touching an infected surface or object and thentouching their mouth, nose, or possibly eyes.[21]Typically, like most respiratory viruses, it is considered to be
the most contagious when people are most symptomatic.
However, cases, who were infected from an asymptomatic
person in the prodrome period of COVID-19, were also reported. Sufficient data are not available on infectiousnessof the disease and research is ongoing.[22]Clinical Progression-Diagnosis
Before SARS-CoV cases, it was thought that human CoVs
leads to cold-like upper respiratory infection and self-limiting lower respiratory infection. The first death due to coronaviruses has reported by the isolation of SARS-CoV from apatient with pneumonia in China. As in other respiratoryinfected viruses and previous beta-CoV, similarities present
in the clinical aspects of COVID-19 infections, it is known
that clinical picture varies from simple respiratory infection
findings to septic shock. Similar to SARS CoV and MERS CoV

4Sahin et al., 2019 Novel Coronavirus (COVID-19) Outbreak / doi: 10.14744/ejmo.2020.12220

that caused epidemics in the past years, the first symptoms
are commonly defined as fever, cough, shortness of breath.
[19]
Although diarrhea was presentin about 20-25% of patients with MERS-CoV or SARS-CoV infection, intestinal
symptoms were rarely reported in patients with COVID-19.
In another study of 99 patients, chest pain, confusion, andnausea-vomiting were noted in addition to previous findings.[23] On X-rays or thorax CT imaging of the examined patients, unilateral or bilateral involvement compatible withviral pneumonia was found, and bilateral multiple lobularand subsegmental consolidation areas were observed inpatients hospitalized in the intensive care unit.[24, 25]
In a cohort study of 41 hospitalized patients, fever, dry
cough, myalgia and fatigue symptoms were reported inmost patients, and less often, symptoms of expectoration,
headache, hemoptysis and diarrhea were also observed.[24]According to that study, comorbidities such as underlying
diabetes mellitus, hypertension, and cardiovascular disease were found in about half of these patients. Besides,
patients developed dyspnea accompanied by abnormal
thorax CT compatible with pneumonia mean eight days after the admission. Complications include ARDS, acute heartdamage, secondary infections, and pneumothorax. Similarly to the previous data, X-rays or thorax CT images of thepatients revealed unilateral or bilateral lung involvement,
compatible with viral pneumonia. Bilateral multiple lobularand subsegmental consolidation areas were present in patients in the intensive care unit.[24] The patients with underlying comorbidity exhibited a more severe clinical course,
as expected by the experience gained from the previous
epidemics.[26]As in SARS and MERS, the diagnosis of 2019 n-CoV infection is based on a history of detailed contact and travel, andprecise laboratory testing. The diagnostic tools are molecular methods, serology and viral culture. The most common
diagnostic methods are molecular methods as RT-PCR (reverse transcription) or real-time PCR, which are made using
RNA from respiratory samples such as oropharyngeal swabs,
sputum, nasopharyngeal aspirate, deep tracheal aspirate,or bronchoalveolar lavage. In particular, lower respiratory
tract samples can offer significantly higher viral load and genome fraction than upper respiratory tract samples. These
techniques are beneficial in terms of evaluating the results
quickly, showing the genome structure and viral load.[25]The sensitivity of antibody detection is generally lower
than molecular methods and is mostly used in retrospective diagnosis. Viral culture is a more time consuming
method compared to the other methods. Culture is much
more useful in the first stage of outbreaks before other diagnostic methods become clinically available. In addition,

viral cultures can be used in the in-vitro and in-vivo antiviral treatment and vaccine evaluation trials.[3]Coronavirus from Sars to Mers
SARS-CoV, which originated from China and then was
spread to other parts of the world with hospital-acquired
infectious cases, had a mortality rate of 10%, and wastransmitted to 8000 people during an 8-month outbreakin 2002-2003.[21] In 2012, MERS-CoV, when it emerged in
Arabian Peninsula MERS-CoV, spread to 27 countries with35.6% mortality rate in 2220 cases. It is known that bothof them are zoonotic viruses showing hospital-acquiredand human-to-human transmission.[21, 22] Similar dynamics
apply for COVID-19 that was originated from Wuhan andthe current the rate of mortality from this infection is about
2%. CoVs can use different receptors and pathways whenentering the cell. SARS-CoV usually infects young people,
MERS-CoV people aged above 50 years and COVID-19 infects middle age and above. Comparing non-respiratorycomplications, MERS-CoV involve the cardiovascular system more frequently than SARS-CoV and frequently requirevasopressor treatment.[3, 19, 20] Case series have reported
that COVID-19 affects the cardiovascular system.[23] Acutekidney failure was more commonly seen in SARS-CoV and
MERS-CoV epidemics compared to COVID-19.[3, 26] Whereas
radiological findings are present in all three pathogens,airspace opacifications are seen in SARS-CoV and groundglass appearance in MERS-CoV and COVID-19.[3, 26] Hospital-acquired secondary infections have been defined in
all three pathogens.[3, 23] There are no studies that report adefinitely successful drug for their treatment.[24] In terms of
epidemic periods, SARS-CoV ended in less than a year, andthe MERS-CoV epidemic lasted for seven years despite its
spread to more restricted areas and. The question of how
long the novel COVID-19 outbreak will last is a questionthat everyone is curious about.

Treatment & Protection
In general, there are few or no treatment options for viraldiseases that occur suddenly.[24] In parallel with this knowledge, today there is no vaccine or effective treatment toprevent COVID-19 infection. Molecules are being tested
for COVID-19 in in-vitro and human-based SARS-CoV and
MERS-Cov trials. Studies evaluating the antiviral activity
of types I and II interferons have reported, interferon-beta(IFNb), as the most potent interferon, was reducing in- vitro MERS-CoV replication.[19] According to a human MERSCoV case report from South Korea, the use of the combination of Lopinavir/Ritonavir (LPV/RTV) (Anti-HIV drugs),
pegylated interferon and ribavirin provided a successful

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viral clearance.[23] For this purpose, a randomized control
trial (MIRACLE Trial), that aimed to determine whether
LPV/RTV-IFNb improved clinical results in MERS-CoV patients, was initiated in 2016 and 76 patients were enrolled.
[27]
Although another antiviral drug, remdesivir was used in
the first case reported from the United States of America,
seemed successful, controlled studies with more cases areneeded.[21] In-vitro studies have shown that viral RNA transcription was terminated with remdesivir in early stage.[28, 29]
There are publications demonstrating that remdesivir has
a strong antiviral activity in epithelial cell cultures against
SARS-CoV, MERS-CoV and related zoonotic bat CoVs.[30, 31]
Many measures should be taken, such as timely publication of epidemic information for elimination of the sourceof infection, early diagnosis, reporting, isolation, supportive treatments and for avoiding unnecessary panic. CDC
reminds basic measures such as hand washing, using disinfectant solutions, avoiding contact with patients in orderto prevent the spread of viruses by droplets. Precautionary
actions including the provision of medicines supply chains,
personal protective equipment, and hospital supplies
should be made in a short time for the protection of theChinese people and global health, especially in the places
with close travel ports to major Chinese ports.[32]Based on the 2003 SARS-CoV epidemic experience, the Chinese government takes many effective measures including
closing public transport, reducing migration and promoting personal protection with masks in Wuhan and otherprovinces. Hence, there are reported cases of infected hospital personnel, healthcare staff should be informed about
taking personal protective measures such as the use ofgloves, eye masks and N95 masks during the examinationof patients with a suspected history of COVID-19 contact ortravel to China.[11, 33]

5Figure 1. The number of daily new COVID-19 cases through January
22 and February 11, 2020.[35]Figure 2. Growth factor of 2019- nCoV out-break between January
23 and February 11, 2020 outbreak.[36]Future Projections

is expected to reach peak at the beginning of March 2020
(80 days from the onset). The duration between onset ofsymptoms and isolation is about 6 days, and its expectedthat each one day reduction in this period will decrease thesize of peak population by 72-84% and cumulative infectedcases and deaths by 68-80%. It is estimated that with theeffects of integrated interventions such as promoting theuse of face masks and reduced traveling, each 10% reduction in transmission rate, the size of peak population will
decrease by 20-47% and cumulative infected cases anddeaths will decrease by 23-49%.[34]

Near future course of COVID-19, which as of 12 Şubat 2020
has spread to 25 countries in total on 4 continents with
43.103 confirmed cases and 1.018 deaths, 1.017 being in
mainland China and 1 in the Philippines, arouses public interest.[9] Since COVID-19 is very similar to SARS-CoV, some
important features of SARS epidemic are guiding the predictions on current epidemic. According to the logisticalmodelling studies performed by combining daily numbers
from COVID-19 cases (Fig. 1) with data obtained in SARS
epidemics; timely diagnosis is essential for quarantine andintegrated interventions to control the outbreak. Currently
growth factor (New cases of everyday/cases of previousday) of COVID-19 started to fall below 1 threshold (Fig. 2). If
the current trend continues, the number of infected people

Owing to the measures by Chinese government, including
passing laws for effective infection management, supports
accelerating the diagnosis and treatment such as distribution of more than 30.000 PCR- fluorescent probe kits to determined diagnosis centers in Wuhan, and closing Wuhan
and nearby Huang Guang provinces, the number of casses
are expected to be below the estimates. Rapid diagnosis
with quarantine and integrated interventions will have agreat effect on future trends of the outbreak. Although COVID-19 has a similar spread with SARS and MERS, it exhibits
lower mortality rates. However, variables such as traveler
flow due to the Spring Festival and cross-border spread of
infection require further research about advanced intervention strategies in order to make more precise predictions. As

6Sahin et al., 2019 Novel Coronavirus (COVID-19) Outbreak / doi: 10.14744/ejmo.2020.12220

imposition of globalization, coronaviruses will cause spreads
and outbreaks with different-mutant strains similarly in the
coming years. With increased scientific collaboration, which
is a result of globalization, we may have more powerfulmeans of fighting against coronaviruses, in which we know
the genome structure very well in the future.[34]Disclosures
Peer-review: Externally peer-reviewed.
Conflict of Interest: None declared.
Authorship Contributions: Concept – A.R.S., A.E.; Design – A.S.,
P.A.; Supervision – Y.D., A.C.; Materials – A.M.T., A.C., M.S.; Data collection &/or processing – A.S., M.S., A.T.; Analysis and/or interpretation – R.O., A.S.; Literature search – A.S., A.T.; Writing – A.S., P.A.,
Y.D.; Critical review – A.S., A.E.

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36. Growth Factor Chart of 2019- nCoV outbreak. Available Online: https://www.worldometers.info/coronavirus/coronavirus-cases/ (Accessed on 12 February, 2020).