As China’s surging Covid-19 infections hit a new record on Friday – with more than 32,000 local infections reported – overseas public health experts flagged that the numbers may not be a true reflection of cases. Several factors could be contributing to an underestimation of the extent of the outbreak, they warned. “I think China is probably underestimating the cases that are really occurring,” said Peter Collignon, infectious disease expert and professor at the Australian National University’s medical school. Collignon pointed to the fast spread of the Omicron variant, the potential for people not to report results from antigen self-test kits and the large number of unvaccinated elderly people, which would usually be accompanied by more deaths. While antigen self-test kits are available on the market, positive results must be confirmed with PCR tests. Some local governments, including Jilin province and Shanghai, have distributed them to residents for free to ease testing bottlenecks. Huang Yanzhong, a senior fellow for global health at US think tank the Council on Foreign Relations, echoed Collignon’s concerns about the use of rapid antigen testing. “Some people may refrain from reporting positive tests because they do not want to be quarantined. This may increase the chance of under-reporting and could lead to further transmission,” Huang said. China has its own method of categorising Covid-19 cases, into symptomatic cases and asymptomatic infections. Both are reported daily by health authorities, with most cases in the latest outbreaks showing no symptoms. People who test positive but are asymptomatic are sent to facilities for isolation and monitoring to cut the transmission chain, while symptomatic patients are treated in hospitals. China also categorises Covid-19 deaths narrowly, generally counting only those who die directly from a pneumonia related to the infection. Many other places, including the United States, Britain and Hong Kong, do not differentiate between people who die with or from Covid-19, as long as it was a contributing factor. China’s Covid-19 wave spurs return of tighter controls China has reported six deaths – four in Beijing, one in Henan and another in Sichuan – this month, its first fatalities from Covid-19 in six months. All were elderly people with underlying diseases. Throughout the pandemic, there have been a total of 5,232 deaths in mainland China attributed to Covid-19. Shanghai generated widespread scepticism when it reported a death toll of zero out of 130,000 cases between March 1 and April 7. The mortality number was updated to nearly 600 in more than 625,000 infections at the end of May, when the city’s two-month lockdown was lifted. In contrast, Hong Kong – which has a similar low vaccination uptake among the elderly and a population less than one third of Shanghai’s – reported more than 9,000 fatalities and 1.19 million infections in its fifth wave. “The main problem for China is that there are not enough elderly being vaccinated and that’s why many people think the death toll was under-reported in Shanghai,” Collignon said. “I think the number could be underestimated in this round of outbreaks.” According to the Shanghai Health Commission, about 62 per cent of Shanghai’s 5.42 million people aged over 60 had been fully vaccinated as of April 15. Only 38 per cent had received a booster shot. National Health Commission (NHC) data shows 85 per cent of the country’s over-60s had been given primary immunisation, but only 67 per cent went on to get a booster dose. This compares to 92 per cent and 70.7 per cent in the US, 91.2 per cent and 85.9 per cent in Germany, and 92.4 per cent and 90.3 per cent in Japan. The Chinese government has previously responded to doubts over its Covid-19 data, saying the low mortality is proof that its strategy of strict lockdowns and mass quarantine works. Chinese migrant workers stranded in Guangzhou’s Covid-19 homeless crisis At a press conference last month, Wu Liangyou, deputy director of the NHC’s Disease Prevention and Control Bureau, compared China’s figures with those of the United States. Citing World Health Organization figures, Wu said that while more than 1 million people died of Covid-19 out of 95 million cases in the US, only 5,226 people died in mainland China where 1 million cases were logged. “The results are telling. We should have confidence in our [dynamic zero] strategy,” Wu said.