Nearly half a million people may have had Covid-19 in Wuhan - study

According to a study by the Chinese Center for Disease Control and Prevention (CDC), nearly half a million residents in Wuhan - the Chinese city where the novel coronavirus first emerged may have been infected with Covid-19.

The new number from the study is almost 10 times the official number of confirmed cases, reports the CNN.

The study used a sample of 34,000 people in the general population in Wuhan - the original epicenter of the pandemic - and other cities in Hubei province, as well as Beijing, Shanghai, and the provinces of Guangdong, Jiangsu, Sichuan and Liaoning to estimate Covid-19 infection rates.

The researchers found an antibody prevalence rate of 4.43% for Covid-19 among residents in Wuhan, a metropolis of 11 million people. As of Sunday, Wuhan had reported a total of 50,354 confirmed cases of Covid-19, according to the Wuhan Municipal Health Commission.

The study aimed to estimate the scale of past infections in a population by testing blood serum samples from a pool of people for coronavirus antibodies. Its findings are not taken to be final statistics of how many people in a given area have been exposed to the virus.

The Chinese CDC said the study was conducted a month after China "contained the first wave of the Covid-19 epidemic."

The prevalence rate outside of Wuhan is significantly lower, the study showed. In other cities in Hubei, only 0.44% of residents surveyed were found to have coronavirus antibodies.

Outside the province, antibodies were only detected in two people among the more than 12,000 residents surveyed.

The results of the study were revealed in a Chinese CDC post on social media Monday. It did not mention whether the study has been published in academic journals.

Yanzhong Huang, a senior fellow for global health at the Council on Foreign Relations, said the study points to a problem of underreporting in infections during the height of the outbreak in Wuhan, partly due to the chaos at the time and a failure to include asymptomatic cases in the official count of confirmed cases.

In January and February, patients with fevers flooded Wuhan's hospitals, which lacked the manpower, testing kits and medical resources to diagnose and treat them. Instead, many were told to go home and self-isolate -- some ended up infecting other family members, while others died at home without being recorded in the Covid-19 death tolls.

Underreporting is a problem faced by health authorities in many countries, often due to a lack of capacity and resources. Antibody studies conducted by researchers in other parts of the world also show the coronavirus was much more prevalent than official numbers suggest.

A study sponsored by the New York State Department of Health, for example, showed that by the end of March, one in seven New York adults had Covid-19 -- about 10 times higher than the official account. In August, another study found coronavirus antibodies in more than 27% of the 1.5 million New York City residents tested.