Chinese nurses wearing protective clothing in Wuhan, China Costfoto/PA Images

China has reported a massive increase in the number of its citizens infected by the new coronavirus, after officials there changed how cases were defined. The numbers now include people who are less seriously ill.

After a week of cases appearing to level out in China, where the outbreak began, the number shot up on Wednesday, with 15,152 people diagnosed with the virus causing the newly named disease, covid-19. A total of 254 people in China died on Wednesday from the coronavirus.

The World Health Organization had warned earlier this week that it was “way too early” to say which direction the epidemic would go after the statistics suggest infections might be slowing.


David Heymann at the London School of Hygiene and Tropical Medicine told New Scientist the sudden spike yesterday was a result of Chinese authorities changing the definition of coronavirus cases.

“They’ve changed their case definition to include people who are less ill,” he says. “It’s good because we’ll now better understand the full spectrum of disease in China, we’ll understand how many are having less serious disease, and this will also have an impact when they are doing the ratio of deaths to cases. [Until] now we have a skewed idea of deaths.”

The change in the ratio of cases to deaths would appear to suggest the virus is less deadly than previously thought, though it is too early to tell, says Heymann.

China has made the change in response to requests from the WHO, in order to get a better idea of what is going on, says Heymann. The move is a positive one, he says. “It will help in deciding which strategies are working and which might not be working.”

The WHO is late today on releasing its daily “situation report” on the virus’s spread, which is usually published in the early morning. The agency couldn’t be reached for comment on why.

China is reported to have sacked two senior officials in Hubei province, where 13,332 of the cases were diagnosed yesterday, after the new figures were released.

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