Coronavirus Disease 2019 (COVID-19) (2019-nCoV)

Updated: Feb 27, 2020
Author: David J Cennimo, MD, FAAP, FACP, AAHIVS; Chief Editor: Michael Stuart Bronze, MD

Coronavirus disease 2019 (COVID-19) is defined as illness caused by a novel coronavirus now called severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2; formerly called 2019-nCoV), which was first identified amid an outbreak of respiratory illness cases in Wuhan City, Hubei Province, China. [1] It was initially reported to the WHO on December 31, 2019. On January 30, 2020, the WHO declared the COVID-19 outbreak a global health emergency. [2, 3]

Illness caused by SARS-CoV-2 was recently termed COVID-19 by the WHO, the new acronym derived from "coronavirus disease 2019." The name was chosen to avoid stigmatizing the virus's origins in terms of populations, geography, or animal associations. [4, 5] On February 11, 2020, the Coronavirus Study Group of the International Committee on Taxonomy of Viruses issued a statement announcing an official designation for the novel virus: severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). [6]

2019-2020 Outbreak

As of February 27, 2020, COVID-19 has been confirmed in more than 82,000 individuals (mostly in China) and has resulted in more than 2,800 deaths. Outside of China, infections have been reported in an increasing number of countries, including Hong Kong, Macau, Taiwan, Afghanistan, Algeria, Australia, Austria, Bahrain, Belgium, Brazil, Cambodia, Canada, Croatia, Denmark, Estonia, Egypt, Finland, France, Georgia, Germany, Greece, India, Iran, Iraq, Israel, Italy, Japan, Kuwait, Lebanon, Malaysia, Nepal, North Macedonia, Norway, Oman, Pakistan, Philippines, Romania, Russia, Sri Lanka, Singapore, Spain, Sweden, Switzerland, Thailand, The Republic of Korea, United Arab Emirates, United Kingdom, United States, and Vietnam. [7]

In the United States, 60 cases have been reported as of February 27, 2020, in the states of Washington, Illinois, California, Arizona, Wisconsin, Texas, and Massachusetts. [8, 9] Most of these cases (42) involve persons who were infected on the Diamond Princess cruise ship near Japan. On February 26, 2020, the first case of COVID-19 not associated with travel from China or known contact with an infected traveler was reported in California. [10]

The Centers for Disease Control and Prevention (CDC) has concluded, at least currently, that the health risk in the United States is generally low, although they are taking proactive preparedness precautions. Person-to-person spread of SARS-CoV-2 has been reported in the United States. [11, 12] Individuals who believe they may have been exposed to SARS-CoV-2 should immediately contact their healthcare provider.

Currently, travelers from Wuhan, China, are undergoing entry screening at several major US airports, including Atlanta (ATL), Chicago (ORD), Los Angeles, (LAX) New York City (JFK), and San Francisco (SFO). [13] This number may increase as needed to screen travelers.

Healthcare personnel are also referred to Medscape’s Novel Coronavirus Resource Center for the latest news, perspective, and resources.

Route of transmission

Transmission is believed to occur via respiratory droplets from coughing and sneezing, as with other respiratory pathogens, including influenza and rhinovirus. [14] According to the WHO, the spread of SARS-CoV-2 in China seems to be largely limited to family members, healthcare providers, and other close contacts and is probably being transmitted by respiratory droplets. WHO officials project that the outbreak is containable if that pattern holds. Severe cases in China have mostly been reported in adults older than 40 years old with significant comorbidities and have skewed toward men. [9] Relatively few young children have been identified and those infected seem to have mild illness. [15]

Recently released data have suggested that asymptomatic patients are still able to transmit infection. This raises concerns for the effectiveness of isolation. [16, 17] Zou et al followed viral expression through infection via nasal and throat swabs in a small cohort of patients. They found increases in viral loads at the time that the patients became symptomatic. One patient never developed symptoms but was shedding virus beginning at day 7 after presumed infection. [18]

An initial report of 425 patients with confirmed COVID-19 in Wuhan, China, attempted to describe the epidemiology. Many of the initial cases were associated with direct exposure to live markets, while subsequent cases were not. This further strengthens the case for human-to-human transmission. The incubation time for new infections was found to be 5.2 days, with a range of 4.1-7 days. The longest time from infection to symptoms seemed to be 12.5 days. At this point, the epidemic had been doubling approximately every 7 days, and the base reproductive number was 2.2 (meaning every patient infects an average of 2.2 others). [19] Further data will likely better define the clinical course, incubation time, and duration of infectivity.

Diagnostic testing

The CDC has developed a diagnostic test for detection of the virus and has requested special emergency authorization from the FDA for its use. [20] The test is a real-time reverse transcription–polymerase chain reaction (rRT-PCR) assay that can be used to diagnose the virus in respiratory and serum samples from clinical specimens. [13]

Of note, commercially available molecular tests for respiratory viruses (even those detecting endemic coronaviruses) have not demonstrated the ability to detect SARS-CoV-2. Australian scientists have successfully grown the virus in cultures. [21]

Treatment of COVID-19

No specific antiviral treatment is recommended for COVID-19. Infected patients should receive supportive care to help alleviate symptoms. Vital organ function should be supported in severe cases. [22]

According to a consensus statement from a multicenter collaboration group in China, chloroquine phosphate 500-mg twice daily in tablet form for 10 days may be considered in patients with COVID-19 pneumonia. [23] Wang et al reported that chloroquine effectively inhibits SARS-CoV-2 in vitro. [24] No vaccine is currently available for SARS-CoV-2. Avoidance is the principal method of deterrence.

A phase 1 clinical trial is now planned for an experimental vaccine against SARS-CoV-2, mRNA-1273, by Moderna.

Infection control

Patients who are under investigation for COVID-19 should be evaluated in a private room with the door closed (an airborne infection isolation room is ideal) and asked to wear a surgical mask. All other standard contact and airborne precautions should be observed, and treating healthcare personnel should wear eye protection. [25]

Background

Coronaviruses comprise a vast family of viruses, 7 of which are known to cause disease in humans. Some coronaviruses that typically infect animals have been known to evolve to infect humans. SARS-CoV-2 is likely one such virus, postulated to have originated in a large animal and seafood market. Recent cases involve individuals who reported no contact with animal markets, suggesting that the virus is now spreading from person to person. [26]

Severe acute respiratory syndrome (SARS) and Middle East respiratory syndrome (MERS) are also caused by coronaviruses that “jumped” from animals to humans. More than 8,000 individuals developed SARS, nearly 800 of whom died of the illness (mortality rate of approximately 10%), before it was controlled in 2003. [27] MERS continues to resurface in sporadic cases. A total of 2,465 laboratory-confirmed cases of MERS have been reported since 2012, resulting in 850 deaths (mortality rate of 34.5%). [28]

The full genome of SARS-CoV-2 was first posted by Chinese health authorities soon after the initial detection, facilitating viral characterization and diagnosis. [13] The CDC analyzed the genome from the first US patient who developed the infection on January 24, 2020, concluding that the sequence is nearly identical to the sequences reported by China. [13] SARS-CoV-2 is a group 2b beta-coronavirus that has at least 70% similarity in genetic sequence to SARS-CoV. [28]

Prognosis and Severity of COVID-19 Compared With SARS and MERS
Early reports have described COVID-19 as clinically milder than MERS or SARS in terms of severity and case fatality rate. [28] Thus far, the fatality rate for COVID-19 appears to be around 2%. [9]

Early in the outbreak, WHO reported that severe cases in China had mostly been reported in adults older than 40 years old with significant comorbidities and skewed toward men, although this pattern may be changing. [9]

In an initial report of 41 patients infected in Wuhan, China, Huang et al reported a 78% male predominance, with 32% of all patients reporting underlying disease. The most common clinic finding was fever (98%), followed by cough (76%) and myalgia/fatigue (44%). Headache, sputum production, and diarrhea were less common. The clinical course was characterized by the development of dyspnea in 55% of patients and lymphopenia in 66%. All patients with pneumonia had abnormal lung imaging findings. Acute respiratory distress syndrome (ARDS) developed in 29% of patients, [29] and ground-glass opacities are common on CT scans. [30]

History, Symptoms of Infection, and Potential Complications
Although data are limited early in the COVID-19 outbreak, presentations of the illness have ranged from asymptomatic/mild symptoms to severe illness and mortality. Symptoms may include fever, cough, and shortness of breath. [31] Other symptoms, such as malaise and respiratory distress, have also been described. [28]

Symptoms may develop 2 days to 2 weeks following exposure to the virus. [31] Although initial reports have centered on patients with severe illness leading to hospitalization, milder and even asymptomatic cases may be possible. Further research is needed to address the full spectrum of clinical illness.

Clinicians evaluating patients with fever and acute respiratory illness should obtain information regarding travel history or exposure to an individual who recently returned from China. [32]

Patients with suspected COVID-19 should be reported immediately to infection-control personnel at their healthcare facility and the local or state health department. Current CDC guidance calls for the patient to be cared for with airborne and contact precautions (including eye shield) in place. [25] Patient candidates for such reporting include those with fever and symptoms of lower respiratory illness who have travelled from Wuhan City, China, within the preceding 14 days or who have been in contact with an individual under investigation for COVID-19 or a patient with laboratory-confirmed COVID-19 in the preceding 14 days. [32]

Early in the outbreak, one patient with COVID-19 (a 61-year-old man with an underlying abdominal tumor and cirrhosis) was admitted with severe pneumonia and respiratory failure. Complications of infection included severe pneumonia, septic shock, acute respiratory distress syndrome (ARDS), and multiorgan failure, resulting in death. [28]

Diagnostic Testing and Workup
Currently, diagnostic testing for SARS-CoV-2 infection can be conducted only by the CDC. [14]

State health departments with a patient under investigation (PUI) should contact CDC’s Emergency Operations Center (EOC) at 770-488-7100 for assistance with collection, storage, and shipment of clinical specimens for diagnostic testing by the CDC. Specimens from the upper respiratory tract, lower respiratory tract, and serum should be collected to optimize the likelihood of detection. [32]

Laboratory testing

If laboratory testing confirms an alternate pathogen, SARS-CoV-2 can be excluded, although this recommendation may change in the future. [33]

The CDC has developed a diagnostic test for detection of the virus and has requested special emergency authorization from the FDA for its use. [20] The test is a real-time reverse transcription–polymerase chain reaction (rRT-PCR) assay that can be used to diagnose the virus in respiratory and serum samples from clinical specimens. [13]

In patients with suspected COVID-19, virus isolation in cell culture or initial characterization of viral agents recovered in cultures of specimens is not recommended for biosafety reasons. [32]

Leukopenia and lymphopenia were common among early cases. [28, 29]

Chest radiography

Chest radiography may reveal pulmonary infiltrates. [34]

CT scanning

CT scan may reveal ground-glass infiltrates or consolidation, almost always bilateral. [29]

Treatment and Prevention of COVID-19

No specific antiviral treatment is recommended for COVID-19. Infected patients should receive supportive care to help alleviate symptoms. Vital organ function should be supported in severe cases. [22]

According to a consensus statement from a multicenter collaboration group in China, chloroquine phosphate 500-mg twice daily in tablet form for 10 days may be considered in patients with COVID-19 pneumonia. [23] Wang et al reported that chloroquine effectively inhibits SARS-CoV-2 in vitro. [24]

No vaccine is currently available for SARS-CoV-2. Avoidance is the principal method of deterrence.

A phase 1 clinical trial is now planned for an experimental vaccine against SARS-CoV-2, mRNA-1273, by Moderna.

General measures for prevention of viral respiratory infections include the following: [22]

Handwashing with soap and water for at least 20 seconds. An alcohol-based hand sanitizer may be used if soap and water are unavailable.
Individuals should avoid touching their eyes, nose, and mouth with unwashed hands.
Individuals should avoid close contact with sick people.
Sick people should stay at home (eg, from work, school).
Coughs and sneezes should be covered with a tissue, followed by disposal of the tissue in the trash.
Frequently touched objects and surfaces should be cleaned and disinfected regularly.
Infection control

Patients who are under investigation for COVID-19 should be evaluated in a private room with the door closed (an airborne infection isolation room is ideal) and asked to wear a surgical mask. All other standard contact and airborne precautions should be observed, and treating healthcare personnel should wear eye protection. [25]

CDC Update and Interim Guidance on Outbreak of 2019 Novel Coronavirus (2019-nCoV) (COVID-19)
The CDC has issued interim guidance for the COVID-19 outbreak, including screening, testing, and treatment recommendations. [35]

Patient screening in healthcare facilities

Screening recommendations are based on the overall objective of rapidly containing transmission of COVID-19 and preventing further spread.

Patients who present for care should undergo assessment for exposures associated with COVID-19 risk and for symptoms known to be consistent with this infection. Importantly, the known signs and symptoms of COVID-19 overlap with those of other viral respiratory tract infections, so other respiratory illnesses (eg, influenza) should be included in the differential diagnoses.

Patients with fever or symptoms of lower respiratory tract infection (eg, cough, shortness of breath) who have travelled to mainland China within the preceding 14 days or who have had close contact with an individual with confirmed COVID-19 should prompt an infection control protocol, as follows:

The patient should be a given a surgical mask to wear.
He or she should be directed to a separate area, if possible, that is at least 6 feet away from other people.
Further evaluation should be conducted in a private room with the door closed. An airborne infection isolation room (AIIR), if available, is ideal.
Healthcare personnel who enter this room should observe standard precautions and contact precautions and should use eye protection.

The healthcare facility’s infection control personnel and local health department should be contacted immediately to determine if the patient should be considered a patient under investigation (PUI) for COVID-19 and to undergo testing for the virus.

Criteria to guide evaluation and testing of patients under investigation for COVID-19

Whether a patient is a PUI for COVID-19 should be determined by the local health department in consultation with clinicians. CDC’s clinical criteria have been developed based on known information about this novel virus and are informed by details known about SARS and MERS.

Clinical Features AND Epidemiologic Risk
Fever or signs/symptoms of lower respiratory illness AND A history of close contact with an individual with laboratory-confirmed COVID-19 within 14 days of symptom onset
Fever and signs/symptoms of a lower respiratory illness AND A history of travel from Hubei Province, China, within 14 days of symptom onset
Fever and signs/symptoms of a lower respiratory illness requiring hospitalization AND A history of travel from mainland China within 14 days of symptom onset

Table 1. CDC Clinical Criteria for COVID-19

Reporting, testing, and specimen collection

In the event that a patient is classified a PUI for COVID-19, infection-control personnel at the healthcare facility should immediately be notified. Upon identification of a PUI, state health departments should immediately contact CDC’s Emergency Operations Center (EOC) at 770-488-7100 and complete a 2019-nCoV PUI case investigation form. The EOC will provide assistance with the obtaining, storing, and shipping of appropriate specimens to the CDC. Diagnostic testing for COVID-19 can be performed only at the CDC.

The CDC recommends collecting and testing upper respiratory specimens (oropharyngeal and nasopharyngeal swabs) and lower respiratory specimens (sputum, if possible) in patients with a productive cough for initial diagnostic testing. Sputum induction is not indicated. Once a PUI is identified, specimens should be collected as soon as possible.

Treatment of COVID-19

Treatment of COVID-19 is supportive, as no vaccine or specific treatment is yet available.

Hospitalized patients with COVID-19 should be managed in a private room with the door closed (an AIIR is ideal).

Home care and isolation may be an option for some persons, based on an assessment of clinical and public health. Such patients should be monitored by public health officials to the extent possible.

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