COVID-19 & SARS-CoV-2
First published Feb. 13, 2020.
Last updated Apr. 8, 2020 @ 5 pm PT.
The novel coronavirus, SARS-CoV-2, is the cause of COVID-19, a severe acute respiratory disease first detected in Wuhan, China. The spread of COVID-19 is an emerging global health risk that has had a significant impact on the economy and daily lives of people across the globe.
Signs & Symptoms
The Centers for Disease Control & Prevention (CDC) believes at this time that symptoms of COVID-19 may appear in as few as two days or as long as 14 after exposure. Individuals with symptoms including, fever, coughing, and shortness of breath should seek medical advice immediately.1,7 The clinical spectrum of COVID-19 ranges from mild, cold-like symptoms to severe pneumonia, respiratory failure, and in some cases, death.7
Spread of Infection
The WHO has designated the outbreak a global health emergency.3 As of April 8, 2020, there have been 1,511,104 confirmed COVID-19 cases (up 85,008 from yesterday). Of the total cases, 328,661 individuals have recovered, and 88,338 have died (up 6,473 from yesterday), of which 14,695 are from the U.S. (up 1,973 from yesterday). The proportion of infected individuals with mild or no symptoms is missing from this data; accounting for this “hidden” data would mean the case fatality rate (CFR) of COVID-19 is lower than current estimates.4
spread of Infection: U.S. Status Report
The virus responsible for the first reported case of COVID-19 in the U.S. (Jan. 21, 2020) was genetically linked to that of a more recent case, suggesting community transmission in the region. Local and state governments across the United States have begun to implement social distancing guidelines to prevent community spread. Guidelines include proclamations like WA State’s Stay Home, Stay Healthy order, which requires every Washingtonian to stay home unless they need to pursue an essential activity, bans all gatherings for social, spiritual, and recreational purposes, and closes all businesses except those identified as essential. Schools and universities across the country are transitioning to online learning.
Anatomy of SARS-CoV-2
Two months into the COVID-19 outbreak, the combination of many expedited studies have revealed an unprecedented amount of information for a new disease, including the causative virus (SARS-CoV-2), its genetic sequence, PCR assays, and serological analyses. Efforts are rapidly ongoing with the aim of quickly designing effective treatments, such as a vaccine or antiviral drug.
SARS-CoV-2 Mechanism of Action
Once in the body, SARS-CoV-2 recognizes and attaches to a transmembrane protein called ACE2 found mainly on cells that line our airways. The effectiveness of SARS-CoV-2 in triggering respiratory disease may be due to the evolved structure of the Spike (S) protein, which contains the receptor-binding domain for ACE2 and creates the virus’s recognizable ‘crown’ shape. After binding to an ACE2 homodimer, the virus enters the cell through a process called receptor-mediated endocytosis. Inside the cell, the virus releases its RNA and takes advantage of the host cell’s machinery, allowing it to reproduce, escape, and continue infecting human tissue.
Situation in Numbers:
How COVID-19 Compares to Other Outbreaks
As more cases emerge, medical professionals and researchers have been able to identify distinguishing traits of COVID-19. Here is a look at other notable viral diseases to show how COVID-19 compares.
- Huang C, Wang Y, Li X, et al. Clinical features of patients infected with 2019 novel coronavirus in Wuhan, China. The Lancet. January 2020. doi:10.1016/s0140-6736(20)30183-5
- World Health Organization (2020). Novel Coronavirus (2019-NCoV) Situation Reports. who.int/emergencies/diseases/novel-coronavirus-2019/situation-reports/
- Chen N, Zhou M, Dong X, et al. Epidemiological and clinical characteristics of 99 cases of 2019 novel coronavirus pneumonia in Wuhan, China: a descriptive study. The Lancet. 2020.
- “The Urgent Questions Scientists Are Asking About Coronavirus.” The New York Times, 10 Feb. 2020, https://www.nytimes.com/2020/02/10/opinion/coronavirus-china-research.html
- Branswell H. The Coronavirus Questions That Scientists Are Racing to Answer. Scientific American. https://www.scientificamerican.com/article/the-coronavirus-questions-that-scientists-are-racing-to-an swer/. Published January 28, 2020.
- Zhao Y, Zhao Z, Wang Y, Zhou Y, Ma Y, Zuo W. Single-cell RNA expression profiling of ACE2, the putative receptor of Wuhan 2019-nCov. BioRxiv (preprint). 2020. doi:10.1101/2020.01.26.919985
- Centers for Disease Control and Prevention. https://www.cdc.gov/coronavirus/2019-ncov/about/transmission.html. Published January 10, 2020. Accessed March 13, 2020.
- Zhao S, Lin Q, Ran J, et al. Preliminary estimation of the basic reproduction number of novel coronavirus (2019-nCoV) in China, from 2019 to 2020: A data-driven analysis in the early phase of the International Journal of Infectious Diseases. 2020. doi:10.1101/2020.01.23.916395
- @DrewQJoseph AJ, Joseph A, Joseph A, et al. First case of coronavirus spread by a person showing no STAT.
- “Cumulative Number of Reported Probable Cases of Severe Acute Respiratory Syndrome (SARS).” World Health Organization, World Health Organization, 23 July 2015, who.int/csr/sars/country/en/.
- “Middle East respiratory syndrome.” World Health Organization, World Health Organization, emro.who.int/health-topics/mers-cov/mers-outbreaks.html.
- Factsheet about Middle East respiratory syndrome coronavirus (MERS-CoV). European Centre for Disease Prevention and Control.
https://www.ecdc.europa.eu/en/middle-east-respiratory-syndrome-coronavirus/factsheet. Published February 10, 2020. Accessed February 11, 2020.
- Types of Influenza Viruses. Centers for Disease Control and Prevention. https://www.cdc.gov/flu/about/viruses/types.htm. Published November 18, Accessed February 11, 2020.
- “Weekly U.S. Influenza Surveillance Report.” Centers for Disease Control and Prevention, Centers for Disease Control and Prevention, 7 Feb. 2020, www.cdc.gov/flu/weekly/index.htm
- Biggerstaff M, Cauchemez S, Reed C, Gambhir M, Finelli L. Estimates of the reproduction number for seasonal, pandemic, and zoonotic influenza: a systematic review of the literature. BMC Infectious Diseases. 2014;14(1). doi:10.1186/1471-2334-14-480
- Transmission of Avian Influenza A Viruses Between Animals and People. Centers for Disease Control and Prevention. https://www.cdc.gov/flu/avianflu/virus-transmission.htm. Published February 10, 2015. Accessed February 11, 2020.
- Biggerstaff M, Cauchemez S, Reed C, Gambhir M, Finelli L. Estimates of the reproduction number for seasonal, pandemic, and zoonotic influenza: a systematic review of the literature. BMC Infect Dis. 2014;14(1):480. doi:10.1186/1471-2334-14-480
- Fraser C, Cummings DAT, Klinkenberg D, Burke DS, Ferguson NM. Influenza Transmission in Households During the 1918 Pandemic. Am J Epidemiol. 2011;174(5):505-514. doi:10.1093/aje/kwr122
- Morens DM, Fauci AS. The 1918 influenza pandemic: insights for the 21st century. J Infect Dis. 2007;195(7):1018-1028. doi:10.1086/511989
- Lessler J, Reich NG, Brookmeyer R, Perl TM, Nelson KE, Cummings DAT. Incubation periods of acute respiratory viral infections: a systematic review. Lancet Infect Dis. 2009;9(5):291-300. doi:10.1016/S1473-3099(09)70069-6
- Taubenberger JK, Baltimore D, Doherty PC, et al. Reconstruction of the 1918 Influenza Virus: Unexpected Rewards from the Past. mBio. 2012;3(5). doi:10.1128/mBio.00201-12
- 1918 Pandemic (H1N1 virus). https://www.cdc.gov/flu/pandemic-resources/1918-pandemic-h1n1.html. Published March 20, 2019. Accessed March 16, 2020.
- History of 1918 flu pandemic. https://www.cdc.gov/flu/pandemic-resources/1918-commemoration/1918-pandemic-history.htm. Published March 21, 2018. Accessed March 16, 2020.
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