SHANGHAI—Scientists in China studying the coronavirus outbreak said they had found two main types of the disease could be causing infections.
The researchers, from Peking University’s School of Life Sciences and the Institut Pasteur of Shanghai under the Chinese Academy of Sciences, cautioned that their analysis examined a limited range of data, and said follow-up studies of larger data sets are needed to better understand the virus’s evolution.
The preliminary study found that a more aggressive type of the new coronavirus associated with the disease outbreak in Wuhan accounted for about 70 percent of analyzed strains, while 30 percent was linked to a less aggressive type.
The prevalence of the more aggressive virus decreased after early January 2020, they said.
“These findings strongly support an urgent need for further immediate, comprehensive studies that combine genomic data, epidemiological data, and chart records of the clinical symptoms of patients with coronavirus disease 2019 (COVID-19),” they wrote.
Their findings were published on Mar. 3 in the National Science Review, the journal of the Chinese Academy of Sciences.
Experts not directly involved in the study said its findings were interesting, but cautioned against drawing firm conclusions from such preliminary research.
“It’s difficult to confirm studies like this without a direct side-by-side comparison of pathogenicity and spread in, ideally, an animal model, or at least a greatly extended epidemiological study,” said Stephen Griffin, a professor and expert in infection and immunity at Britain’s Leeds University.
Also on Wednesday, one of China’s top medical associations confirmed that the median incubation period of the coronavirus is five to seven days and the maximum 14 days.
The remarks by Du Bin, chairman of the critical care medical branch of the Chinese Medical Association, mark the most conclusive assessment of the virus’ incubation period by a government-affiliated medical organization to date.
