COVID-19 overview

# Overview
Coronavirus, named due to the "crown" like appearance of its surface projections, was first isolated from chickens in 1937. The etiological agent, a novel coronavirus, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), named for the similarity of its symptoms to those induced by the severe acute respiratory syndrome, causing coronavirus disease 2019 (COVID-19), is a virus identified as the cause of an outbreak of respiratory illness first detected in Wuhan, China. On March 12, 2020 the World Health Organization declared the COVID-19 outbreak a pandemic. Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the etiological agent of coronavirus disease 2019 (COVID-19), can be categorized into two major types, L, the major type (~70%) and S, the minor type (~30%). Coronavirus disease 2019 (COVID-19) is caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), a novel coronavirus named for the similarity of its symptoms to those caused by the severe acute respiratory syndrome. Unlike SARS-CoV, transmission of COVID-19 takes place during the prodromal period when those infected are mildly ill and are carrying on with their usual activities. This contributes to the spread of infection. The main pathogenesis of COVID-19 is severe pneumonia, RNAemia, combined with the incidence of ground-glass opacities, and acute cardiac injury. Person-to-person transmission occurs primarily via direct contact or through droplets spread by coughing or sneezing from an infected individual. Coronavirus disease 2019 (COVID-19) is caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Coronavirus disease 2019 (COVID-19) should be differentiated from other diseases presenting with cough, fever, shortness of breath, and tachypnea. Globally, 952,100 cases of COVID-19 have been reported with 48,300 deaths. In the US greater than 200,000 cases have been reported with 5,100 deaths in country. Due rapidly evolving data at this point, the exact incidence rate of Coronavirus disease 2019 (COVID-19) can not be approximated. Prevalent in all the continents of the world, World Health Organization (WHO) has declared COVID-19 outbreak a pandemic. Due to inconsistent reporting and lack of organized data, an exact and universal case-fatality rate of COVID-19 is yet to be established. Middle aged and elderly population seem to be the most commonly affected with a median age of 49 - 56 years. COVID-19 is affecting males more than females. Majority of the cases of COVID-19 have been reported in China and at this point the disease has spread to all the continents of the world. Similar to all viral illnesses, exposure is considered the most significant risk factor for infection with Coronavirus disease 2019 (COVID-19). Individuals at risk for the severe form of the disease include elderly (those aged 60+), cardiovascular disease patients, diabetics, chronic respiratory disease patients, hypertensive patients, cancer patients, and individuals in long term care facilities. Currently, there are no recommended guidelines in place for the routine screening for Coronavirus disease 2019 (COVID-19). Some of the clinical and non-clinical features related to COVID-19 being used to screen suspected individuals are history of international travel, history of exposure to a confirmed COVID-19 case, fever, cough, fatigue, and shortness of breath. In symptomatic patients, the clinical features of the disease usually start within a week, consisting of fever, cough, nasal congestion, fatigue, and other signs of upper respiratory tract infections. Disease progression and severity is manifested by dyspnea and severe chest symptoms corresponding to pneumonia in approximately 75% of the patients. The World Health Organization has published a diagnostic criteria that helps identify patients requiring confirmation of COVID-19 through either PCR or antibody detection tests. This criteria includes several epidemiological and clinical criteria that the patient has to fulfill in order to be either a suspected or confirmed case of COVID-19. History of patients infected with Coronavirus disease 2019 (COVID-19) can include international travel to where COVID-19 is highly prevalent. The most common symptoms that can appear 2 - 14 days after exposure include fever, cough, fatigue, and shortness of breath. The pathognomonic physical examination findings in patients infected with coronavirus include fever, flu-like-symptoms, cough, and body aches. General appearance of the patient infected with coronavirus depends on the incubation period of the illness. Laboratory tests can be done to confirm whether illness may be caused by human coronaviruses. Specific laboratory tests include serology for viral antigen, molecular testing and viral culture. All these tests can be used to confirm infection with coronavirus. Non-specific laboratory findings in COVID-19 include lymphocytopenia, thrombocytopenia, elevated C-Reactive protein, elevated liver function tests (ALT, AST), increased creatine kinase, increased D-Dimer and an increase in the levels of markers of cell damage e.g. troponin, lactate dehydrogenase, interleukin-4, procalcitonin. There are no specific ECG findings associated with coronavirus infection. Non specific findings can include sinus tachycardia, ST-elevation and diffuse T wave inversion. The chest x ray findings in a suspected case of coronavirus infection can mimic the findings in pneumonia. Severe cases of COVID-19 progressing to acute respiratory distress syndrome (ARDS) can show a typical "white-out" on chest x-ray. There are no specific echocardiography/ultrasound findings associated with coronavirus infection. Non specific echocardiographic findings can include left ventricular systolic dysfunction and pericardial effusion. Chest CT scan findings in patients infected with coronavirus can include unilateral or bilateral pneumonia, mottling and ground glass opacity, focal or multifocal opacities, consolidation, and septal thickening with subpleural and lower lobe involvement more likely. There are no specific MRI findings associated with coronavirus infection. MRI can aide in making the diagnosis on the basis of exclusion. There are no other imaging findings associated with COVID-19. Research laboratories have used isolation methods, electron microscopy, serology and PCR-based assays to diagnose coronavirus infections for surveillance studies. Treatment of coronavirus infection includes supportive measures and symptomatic management. No specific treatment is available. Given the emergence of the cases during the influenza season, all patients presenting with COVID-19 were given oral and intravenous antibiotics and Oseltamivir (75 mg twice daily via oral route) empirically. Corticosteroids (methylprednisolone 40 - 120 mg/day) were given as a combined regimen if severe community-acquired pneumonia was diagnosed. Oxygen support (e.g., via nasal cannula and invasive mechanical ventilation) was given to patients indicated by the severity of hypoxemia. Surgery is not indicated in the management of COVID-19. There is currently no vaccine to prevent COVID-19. The best way to prevent infection is to avoid being exposed to this virus. The fact that it is currently flu and respiratory disease season, CDC recommends getting a flu vaccine, taking everyday preventive actions to help stop the spread of germs, and taking flu antivirals if prescribed. Healthcare providers are advised to be on the look-out for people who recently traveled from China and have fever and respiratory symptoms.

# Historical Perspective
Coronavirus, named due to the "crown" like appearance of its surface projections, was first isolated from chickens in 1937. The etiological agent, a novel coronavirus, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), named for the similarity of its symptoms to those induced by the severe acute respiratory syndrome, causing coronavirus disease 2019 (COVID-19), is a virus identified as the cause of an outbreak of respiratory illness first detected in Wuhan, China. On March 12, 2020 the World Health Organization declared the COVID-19 outbreak a pandemic.

# Classification
Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the etiological agent of coronavirus disease 2019 (COVID-19), can be categorized into two major types, L, the major type (~70%) and S, the minor type (~30%).

# Pathophysiology
Coronavirus disease 2019 (COVID-19) is caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), a novel coronavirus named for the similarity of its symptoms to those caused by the severe acute respiratory syndrome. Unlike SARS-CoV, transmission of COVID-19 takes place during the prodromal period when those infected are mildly ill and are carrying on with their usual activities. This contributes to the spread of infection. The main pathogenesis of COVID-19 is severe pneumonia, RNAemia, combined with the incidence of ground-glass opacities, and acute cardiac injury. Person-to-person transmission occurs primarily via direct contact or through droplets spread by coughing or sneezing from an infected individual.

# Causes
Coronavirus disease 2019 (COVID-19) is caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2).

# Differential Diagnosis
Coronavirus disease 2019 (COVID-19) should be differentiated from other diseases presenting with cough, fever, shortness of breath, and tachypnea.

# Epidemiology and Demographics
Globally, 952,100 cases of COVID-19 have been reported with 48,300 deaths. In the US greater than 200,000 cases have been reported with 5,100 deaths in country. Due rapidly evolving data at this point, the exact incidence rate of Coronavirus disease 2019 (COVID-19) can not be approximated. Prevalent in all the continents of the world, World Health Organization (WHO) has declared COVID-19 outbreak a pandemic. Due to inconsistent reporting and lack of organized data, an exact and universal case-fatality rate of COVID-19 is yet to be established. Middle aged and elderly population seem to be the most commonly affected with a median age of 49 - 56 years. COVID-19 is affecting males more than females. Majority of the cases of COVID-19 have been reported in China and at this point the disease has spread to all the continents of the world.

# Risk Factors
Similar to all viral illnesses, exposure is considered the most significant risk factor for infection with Coronavirus disease 2019 (COVID-19). Individuals at risk for the severe form of the disease include elderly (those aged 60+), cardiovascular disease patients, diabetics, chronic respiratory disease patients, hypertensive patients, cancer patients, and individuals in long term care facilities.

# Screening
Currently, there are no recommended guidelines in place for the routine screening for Coronavirus disease 2019 (COVID-19). Some of the clinical and non-clinical features related to COVID-19 being used to screen suspected individuals are history of international travel, history of exposure to a confirmed COVID-19 case, fever, cough, fatigue, and shortness of breath.

# Natural History, Complications and Prognosis
In symptomatic patients, the clinical features of the disease usually start within a week, consisting of fever, cough, nasal congestion, fatigue, and other signs of upper respiratory tract infections. Disease progression and severity is manifested by dyspnea and severe chest symptoms corresponding to pneumonia in approximately 75% of the patients.

# Diagnosis

## Diagnostic study of choice
The World Health Organization has published a diagnostic criteria that helps identify patients requiring confirmation of COVID-19 through either PCR or antibody detection tests. This criteria includes several epidemiological and clinical criteria that the patient has to fulfill in order to be either a suspected or confirmed case of COVID-19.

## History and symptoms
History of patients infected with Coronavirus disease 2019 (COVID-19) can include international travel to where COVID-19 is highly prevalent. The most common symptoms that can appear 2 - 14 days after exposure include fever, cough, fatigue, and shortness of breath.

## Physical Examination
The pathognomonic physical examination findings in patients infected with coronavirus include fever, flu-like-symptoms, cough, and body aches. General appearance of the patient infected with coronavirus depends on the incubation period of the illness.

## Laboratory findings
Laboratory tests can be done to confirm whether illness may be caused by human coronaviruses. Specific laboratory tests include serology for viral antigen, molecular testing and viral culture. All these tests can be used to confirm infection with coronavirus. Non-specific laboratory findings in COVID-19 include lymphocytopenia, thrombocytopenia, elevated C-Reactive protein, elevated liver function tests (ALT, AST), increased creatine kinase, increased D-Dimer and an increase in the levels of markers of cell damage e.g. troponin, lactate dehydrogenase, interleukin-4, procalcitonin.

## Electrocardiogram
There are no specific ECG findings associated with coronavirus infection. Non specific findings can include sinus tachycardia, ST-elevation and diffuse T wave inversion.

## Chest X-ray
The chest x ray findings in a suspected case of coronavirus infection can mimic the findings in pneumonia. Severe cases of COVID-19 progressing to acute respiratory distress syndrome (ARDS) can show a typical "white-out" on chest x-ray.

## Echocardiography
There are no specific echocardiography/ultrasound findings associated with coronavirus infection. Non specific echocardiographic findings can include left ventricular systolic dysfunction and pericardial effusion.

## CT scan
Chest CT scan findings in patients infected with coronavirus can include unilateral or bilateral pneumonia, mottling and ground glass opacity, focal or multifocal opacities, consolidation, and septal thickening with subpleural and lower lobe involvement more likely.

## MRI
There are no specific MRI findings associated with coronavirus infection. MRI can aide in making the diagnosis on the basis of exclusion.

## Other Imaging Findings
There are no other imaging findings associated with COVID-19.

## Other Diagnostic Studies
Research laboratories have used isolation methods, electron microscopy, serology and PCR-based assays to diagnose coronavirus infections for surveillance studies.

# Treatment

## Medical Therapy
Treatment of coronavirus infection includes supportive measures and symptomatic management. No specific treatment is available. Given the emergence of the cases during the influenza season, all patients presenting with COVID-19 were given oral and intravenous antibiotics and Oseltamivir (75 mg twice daily via oral route) empirically. Corticosteroids (methylprednisolone 40 - 120 mg/day) were given as a combined regimen if severe community-acquired pneumonia was diagnosed. Oxygen support (e.g., via nasal cannula and invasive mechanical ventilation) was given to patients indicated by the severity of hypoxemia.

## Surgery
Surgery is not indicated in the management of COVID-19.

## Primary Prevention
There is currently no vaccine to prevent COVID-19. The best way to prevent infection is to avoid being exposed to the virus. As a precaution against coinfection during the flu and respiratory disease season, CDC recommends getting a flu vaccine, taking everyday preventive actions to help stop the spread of germs, and taking flu antivirals if prescribed. Healthcare providers are advised to be on the look-out for people who recently traveled from China and have fever and respiratory symptoms.