A group of researchers led by Chinese doctors reviewed about 26,000 laboratory-confirmed cases recorded in the city, where the coronavirus was first identified, between December and February.
They used lab tests, instead of Chinese government data, because authorities in the country did not count some cases where patients did not show symptoms.
The study, which was run by doctors from Tongji Medical College in Wuhan, Fudan University in Shanghai and Harvard University in Massachusetts, referred to asymptomatic and very mild cases as “unascertained”.
“Here, unascertained cases included asymptomatic cases and those with mild symptoms who could recover without seeking medical care and thus were not reported to authorities,” the researchers said.
The Wuhan researchers have estimated there were more than 26,000 unascertained cases in the city by 18 February, when China was reporting about 72,000 cases on its mainland.
However, the study said the total number of infections could have been much higher than that figure, based on their models.
“We predicted the cumulative number of ascertained cases [in Wuhan] to be 26,252 by February 18, close to the actual reported number of 25,961, while the estimated cumulative number of total cases was 125,959,” the study said.
China has confirmed more than 80,000 cases of Covid-19, with more than 3,000 deaths, on its mainland as of Wednesday.