China could have reported over 2.32 lakh COVID-19 cases by mid-February — more than four times of what was officially announced — if it had followed a broader criterion to count the total number of infections, a study has said.
“We estimated that there were at least 2,32,000 infections in the first epidemic wave of coronavirus in mainland China,” said University of Hong Kong researchers, who conducted a study on the criteria applied by China in counting number of virus cases.
According to China’s National Health Commission (NHC), the total number of confirmed COVID-19 cases in China stood at 82,798 with 4,632 fatalities as of Wednesday.
China has faced severe criticism from the US and other European countries over under-reporting of coronavirus cases and an alleged cover-up.
On April 17, China revised the death toll in virus epicentre Wuhan by 50 per cent to 1,290 additional fatalities, taking the city’s total toll to 3,869.
The total number of confirmed coronavirus cases in Wuhan was revised to 50,333 an increase of 325, according to an official announcement on April 16.
The Wuhan Municipal Headquarters explained the revision, saying they were in accordance to laws and regulations as well as the principle of being responsible to history, the people and the deceased.
In the study published in medical journal The Lancet, researchers said China might have had 2,32,000 confirmed cases rather than the official count of about 55,000 by February 20, if a revised definition adopted earlier in the month had been applied throughout.
“The true number of infections could still be higher than what is currently (being) estimated considering the possibility of under-detection of some infections, particularly those that were mild and asymptomatic even under the broadest case definitions,” a news report on the study by the Hong Kong-based South China Morning Post said on Thursday.
The researchers, led by Peng Wu from the University of Hong Kong’s School of Public Health, looked at the various classification systems used by the Chinese government after the epidemic broke out in Wuhan late December.
China has published seven editions of diagnosis and treatment guidelines, changing the classification system as understanding of the disease developed.
The calculations were based on epidemiological curves, included in a World Health Organisation report published on February 28 after a joint mission to Wuhan.
The curves show the number of cases based on symptoms, onset dates and reporting dates.
In the fifth version of the guidelines released on February 5, China modified its classification of confirmed cases to include diagnosis by symptoms only rather requiring confirmation by both clinical symptoms and laboratory tests, the study said.
The inclusion of these cases led to a sudden jump in confirmed cases before the authorities reversed the decision more than a week later on February 17, it said.
The researchers found that if the fifth definition was used throughout the epidemic, the total number of confirmed cases could have reached 2,32,000 by February 20.
The impact of later versions of diagnosis guidelines cannot be gauged because no data based on symptom onset dated after February 20 has been released yet, it said.
The team found that if the revisions of case classifications were taken into account, the original growth rate estimate would be an overestimate, and epidemiological studies should take into account changes in case definitions.
It also suggested that countries that did not have enough test kits for the disease should include clinical diagnosis in their classification guidelines to better gauge the number of infections and determine the public health response.