Initial information about the novel coronavirus in Wuhan, China

Référence

Li Q, Guan X, Wu P, et al. Early transmission dynamics in Wuhan, China, of novel coronavirus-infected pneumonia. N Engl J Med 2020 Jan 29. doi: 10.1056/NEJMoa2001316. [Epub ahead of print]

Sommaire

This is the initial report from a team of Chinese and international collaborators, working with China's CDC and smaller CDC branches. The first cases the novel Wuhan coronavirus were reported in early December and were sporadic until the end of the year, when the number of cases began to quickly rise. Polymerase chain reaction (PCR) diagnostics became available on January 11, and the government response has steadily increased. This report describes the first 425 confirmed cases (a confirmed case is defined as one with a positive PCR test result or isolation of the virus in culture). Demographics are described separately for cases before January 1 (n = 47), from January 1–11 (n = 248), and from January 12–22 (n = 130). The median age of patients was 56 years early in the outbreak, but is now 61 years. No patients have been younger than 15 years; approximately 80% of patients have been 45 or older. Although two-thirds of the earliest patients were men, the cases later became evenly divided between men and women. Almost all of the earliest cases had exposure to a seafood market, but the more recent patients (75%) have had no contact with the market or with someone who had respiratory symptoms. This suggests the possibility of transmission from asymptomatic persons, which is worrisome. The mean estimated time from exposure to symptom onset is 5.2 days, although inspection of the time to event curve suggests that the median is a bit lower, perhaps 3 days. The authors estimate that almost all persons will show symptoms within 14 days, leading to current quarantine and surveillance recommendations. The average interval from illness onset to seeking care was approximately 5 days. The basic reproductive number (R0) is the number of persons that the average case infects, and is estimated at 2.2. This compares with an R0 of 3 for SARS, but because patients with SARS were sicker, they were identified and isolated more quickly than the current patients with coronavirus who have more mild cases. The case fatality rate was estimated by the World Health Organization as 2% on January 29, 2020, but this may change as more cases are identified, deaths are more completely reported, and/or the virus mutates