Coronavirus disease 2019 (COVID-19) is defined as an 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. 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. On March 11, 2020, the WHO declared COVID-19 a global pandemic, its first such designation since declaring H1N1 influenza a pandemic in 2009.
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. 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).
Route of Transmission
Transmission is believed to occur via respiratory droplets from coughing and sneezing, as with other respiratory pathogens, including influenza and rhinovirus. 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 with significant comorbidities and have skewed toward men. Relatively few young children have been identified and those infected seem to have mild illness.
Recently released data have suggested that asymptomatic patients are still able to transmit infection. This raises concerns about the effectiveness of isolation. 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.
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 strengthened 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). Further data will likely better define the clinical course, incubation time, and duration of infectivity.
On March 10, 2020, Dr. Zunyou Wu of the CCDC delivered a report at the Conference on Retroviruses and Opportunistic Infections (CROI) meeting detailing the latest data from China, including updates on epidemiology and clinical presentation. COVID-19 is still most severe in older adults, but a marked male predominance no longer exists. At presentation, approximately 40% of the cases were “mild” with no pneumonia symptoms. Another 40% were “moderate” with symptoms of viral pneumonia, 15% were severe, and 5% critical. During the course of the illness, 10%-12% of cases that initially presented as the mild or moderate illness progressed to severe, and 15%-20% of severe cases eventually became critical. The mean time from exposure to symptoms was 5-6 days. Patients with mild cases seem to recover within 2 weeks, while patients with severe infections may take 3-6 weeks to recover. Deaths were observed from 2-8 weeks following symptom onset. Interestingly, the completely asymptomatic infection was rare (< 1%) after detailed symptom assessments. Analysis of the virology data does suggest that patients can shed virus 1-2 days before symptoms appear, raising concern for asymptomatic spread.
In Uganda, the Ministry of Health has not expressed the method of testing. The information that we have is that the Uganda Virus Research Institute is using a type of DNA Polymerase Chain Reaction.
The CDC has developed a diagnostic test for detection of the virus and received special Emergency Use Authorization (EUA) from the FDA on February 4, 2020, for its use. 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.
Although the CDC rRT-PCR test was found to have performance issues related to manufacturing of one of the reagents, the CDC has since developed an updated protocol that excludes the need for the third (problematic) component of the test without affecting accuracy. The test kits are now being shipped to US state and local public health laboratories that the CDC has determined to be qualified.
The FDA has issued EUAs for several other tests, as follows:
New York SARS-CoV-2 Real-time Reverse Transcriptase (RT)-PCR Diagnostic Panel (Wadsworth Center, NYSDOH)
cobas SARS-CoV-2 (Roche Molecular Systems, Inc.)
TaqPath COVID-19 Combo Kit (Thermo Fisher Scientific, Inc.)
Panther Fusion SARS-CoV-2 (Hologic, Inc.)
COVID-19 RT-PCR Test (Laboratory Corporation of America)
Lyra SARS-CoV-2 Assay (Quidel Corporation)
Quest SARS-CoV-2 rRT-PCR (Quest Diagnostics Infectious Disease, Inc.)
Abbott RealTime SARS-CoV-2 assay (Abbott Molecular)
Of note, commercially available molecular tests for other 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.
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.
No vaccine is currently available for SARS-CoV-2. Avoidance is the principal method of deterrence.
Numerous collaborative efforts to discover and evaluate the effectiveness of antivirals (eg, remdesivir), immunotherapies (eg, hydroxychloroquine, sarilumab), monoclonal antibodies, and vaccines have rapidly emerged.
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.