China researchers detail coronavirus outbreak

Feb. 19, 2020

As confirmed cases of the coronavirus continue to increase, China recently published a detailed picture of its Covid-19 outbreak.

China's report on the outbreak's epidemiologic patterns covers all Covid-19 cases reported through February 11 and appears in the China CDC Weekly, a publication that is similar to the US Centers for Disease Control and Prevention's Morbidity and Mortality Weekly Report.

The team analyzed more than 72,000 patient records, of which 44,672 were lab-confirmed cases, 16,186 suspected cases, 10,567 clinically diagnosed cases and 889 asymptomatic cases. Of the confirmed cases, 80.9 percent cases were mild, and the vast majority (86.6 percent) of confirmed cases were in people ages 30 to 79 years old.

About 14 percent of the illnesses were severe, which included pneumonia and shortness of breath, and about 5 percent have critical disease, marked by respiratory failure, septic shock, and multi-organ failure. The overall case fatality rate was 2.3 percent, and of 1,023 deaths included in the study, the majority were in people age 60 and older or those with underlying medical conditions.

Epidemiologic curve analysis shows a common source pattern in December, which shifted to a propagated source pattern starting in early January, which the researchers said might reflect several zoonotic events at the outbreak market in Wuhan. Around January 23-26, the epidemic peaked and began to decline, according to the data.

There is no evidence of super-spreader events in healthcare facilities caring for Covid-19 cases, the group wrote. Those events were hallmarks of outbreaks involving severe acute respiratory syndrome (SARS) and Middle East respiratory syndrome coronavirus (MERS-CoV). So far, it's not clear if the difference is due to the virus or prevention tactics, they noted.

China's massive control measures, which started on January 23 with limiting travel in and out of Wuhan, slowed China's epidemic and its spread to the rest of the world, the authors note. But they warn that officials need to prepare for the epidemic to rebound when huge numbers of people in China return to work and school.

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