Chinese epidemiologists rebuke twisting of latest CDC antibody survey
Published: Dec 30, 2020 10:07 PM

Photo: Li Hao/GT

China's latest national epidemiological serum survey, which showed the positive rate of coronavirus antibodies in Wuhan was 4.43 percent, has become a point of attack by the foreign media against the Chinese government for underreporting during the initial stages of the outbreak.

The ratio, which was interpreted by some media outlets as an argument for suggesting that Wuhan may have experienced nearly 10 times higher the number of COVID-19 cases than the roughly 50,000 officially reported. 

When asked about whether the study showed that the number of infections in Wuhan was potentially higher than the officially released figures, Wang Wenbin, a Chinese Foreign Ministry spokesperson, said the concept might have been misunderstood and this kind of disparity is not unique to China.

"Similar reports from other countries have shown that, the ratio of antibodies is generally higher than the ratio of reported infections. Such disparity is due to the characteristics of the illness, habits of those seeking treatment, virus testing capabilities and serum antibody testing measures," Wang said, noting that it can't be easily summed up a singular number and simply multiplying the results of the survey with the number of people in the region.

China's CDC has completed a national epidemiological survey of COVID-19 serum and found that the Chinese population had a low infection rate, according to the report released on Monday. It was conducted among some 34,000 people over a month after China contained the first wave of the COVID-19 outbreak, showing the positive rate of coronavirus antibodies in Wuhan, Central China's Hubei Province, was at 4.43 percent.

It is a common scientific method of conducting in-depth surveys as a measure of understanding the average antibody level of the population, and similar studies have also been conducted in other countries including the US, suggesting that infections might be higher than reported cases, multiple veteran Chinese epidemiologists and experts said.

But it can't be interpreted as persuasive evidence with which to accuse China of deliberately hiding the numbers or underreporting the COVID-19 figures during the early stage of the outbreak, when there was a lack of testing means to establish asymptomatic cases, an expert close to the matter who spoke on condition of anonymity told the Global Times.

Many who might have contracted the virus but showed mild symptoms did not go to the hospital or provided any sample for testing due to very little understanding about the virus at the beginning of the outbreak, he said.

"If they have not been diagnosed, how could we say we deliberately hide them before we had not even found them yet?" the expert said.

The number of people infected with the coronavirus in different parts of the US was anywhere from two to 13 times higher than the reported rates for those regions, the New York Times reported in July, citing the data released by the US CDC. This has not come as a shock or surprise for epidemiologists, the report said.

Yang Zhanqiu, deputy director of the pathogen biology department at Wuhan University, told the Global Times that different methods were used for nucleic and serum antibody test, so those with antibody cannot be detected by nucleic acid tests.

People with the coronavirus antibody but who showed no onset of symptoms can be categorized as asymptomatic carriers. But the virus in those people has a weaker transmission ability, said Yang.

The virologist said that such antibody prevalence rate in Wuhan is normal, and the difference does not only exist in China.

Spain also conducted similar survey in April and May, and found the antibody prevalence ranged between 3.7 to 6.2 percent, which makes the country's infection as high as nearly 3 million, whilst the country's official COVID-19 infections were only 250, 561 in May.

Many Chinese netizens also ridiculed some Western media reports accusing China of hiding the numbers given the CDC study, when the US has been dealing with an outbreak out of control "Millions of people died in the US, and they don't even have any feelings about that?" A netizen said on Weibo.

"What is the meaning of arguing about those numbers? The reality is China has contained the outbreak and we have been moving on and embracing a fresh start in a post-epidemic world," another netizen added.