China’s first wave may have been four times worse than claimed

THE number of people infected in the first wave of China’s coronavirus outbreak may be four times higher than the official figures, new analysis has found.

By Feb 20, authorities had reported roughly 55,000 cases. But according to modelling published in The Lancet, there could have been as many as 232,000 had a broader case definition been applied from the start of the epidemic. Between Jan 15 and March 3, China’s national health commission issued seven different case definitions for classifying coronavirus patients.

Researchers at the University of Hong Kong calculated how the changing definition altered the trajectory of the epidemiological curve, based on data published by the World Health Organisation (WHO) after a visit to China in February. The new modelling found that the changes in case definitions had a “substantial effect” on the figures.

The new estimates for infections in mainland China are based on the fifth case definition used, published in early February. In this, official numbers include cases diagnosed by symptoms only, rather than infections confirmed by clinical symptoms and lab tests.

This decision provoked controversy at the time, and led to a substantial spike in cases – including a jump of roughly 15,000 in one day. Authorities later reversed the decision to broaden the definition.

Had this classification been in place since the beginning of January, researchers estimate that 232,000 people may have been diagnosed with Covid-19 – including 127,000 in Wuhan. By Feb 20, the city, where the outbreak first emerged, had reported 27,000 cases, according to official numbers.

“Still, this would be an underestimate of the number of infections up to that point because it would not have captured some mild or asymptomatic cases,” the report’s authors noted.

Dr Adam Kucharski, an epidemiologist and mathematician at the London School of Hygiene and Tropical Medicine not involved in the study, said the modelling showed “why we need to be careful when interpreting the curve”.

Prof Chris Dye, an infectious disease expert at the University of Oxford, said: “This new article should not be used to promote views that there has been some kind of ‘cover-up’ in China.”

China was accused of concealing the extent of its outbreak when authorities revised Wuhan’s death toll last week, adding 1,290 new fatalities.

The US has suspended WHO funding for at least 90 days after claiming the organisation was too “China-centric”.

The US is the agency’s largest funder and contributed more than $400 million (£320million) in 2019. China yesterday said it would donate $30million to the WHO, which is seeking more than $1billion to fund its Covid-19 battle.