COVID-19 epidemiologic characteristics in Wuhan, China [Classics Series]

This study summary is an excerpt from the book 2 Minute Medicine’s The Classics in Medicine: Summaries of the Landmark Trials

1. This prospective cohort study found that novel coronavirus-infected pneumonia (NCIP) is transmitted via human-to-human contact.

2. The incubation period of NCIP was estimated to be 5.2 days.

Original Date of Publication: January 2020

Study Rundown: In this prospective study, epidemiological data was collected on laboratory-confirmed cases of NCIP in Wuhan, China. Data was collected during the NCIP outbreak, with over half of the cases linked to the Huanan Seafood Wholesale Market. Epidemiological linking data demonstrated that human-to-human transmission occurred, the majority of which were in adults over the age of 60,although these patients may be more likely to experience severe illness due to underlying health conditions and therefore overrepresented in the collected data. Additionally, detection of cases was limited by poor access to reliable testing resources as well as possibility of patients with asymptomatic infection. In summary, this study demonstrated that NCIP is likely transmitted between humans and that older patients may be at higher risk for severe infection.

Click to read the study in NEJM

In-Depth [prospective study]: This present prospective study evaluated patients in Wuhan, China with pneumonia of unknown etiology later confirmed as NCIP (n = 425). Approximately half of patients were male (56%) with a median age of 59 years and no cases in children below the age of 15. Based on data from 10 exposures, mean incubation period was approximately 5.2 days. NCIP case doubling time was estimated at 7.4 days (95%CI 4.2-14) with an R0­ of 2.2 (95%CI 1.4-3.9). For patients with illness onset before January 1st, 2020 (n = 45), mean duration from onset to first medical visit was 5.8 days (95%CI 4.3-7.5). Comparatively, patients with illness onset between January 1st and January 11th (n = 207) was 4.6 days (95%CI 4.1-5.1).

Li Q, Guan X, Wu P, Wang X, Zhou L, Tong Y, Ren R, Leung KS, Lau EH, Wong JY, Xing X. Early transmission dynamics in Wuhan, China, of novel coronavirus–infected pneumonia. New England journal of medicine. 2020 Jan 29.

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