China could face more than 630,000 coronavirus infections a day if it dropped its zero-tolerance approach and followed other countries by lifting travel bans, according to forecasting by Peking University mathematicians. In the report published in China CDC Weekly by the Chinese Centre for Disease Control and Prevention, the four mathematicians argued that China was not ready and could not afford to lift entry-exit quarantine measures without more efficient vaccinations or specific treatment. “The estimates revealed the real possibility of a colossal outbreak which would almost certainly put an unbearable burden on the medical system,” the authors said in the report, dated Wednesday. China’s Covid-19 containment strategy relies on repeated mass mandatory swab testing to identify positive cases each time an infection is found in a new area. Its borders have been closed to most countries since March last year and it has one of the world’s longest quarantine periods. But the measures take a heavy economic toll and critics question their value, given that China has reported only sporadic outbreaks. China’s zero-Covid aim has zero chance now virus has adapted, Sars expert says On Saturday, China reported only 25 confirmed cases of Covid-19, of which 20 were imported. Experts have instead urged authorities to base their strategies on assessments of post-vaccination antibody levels in the general population and the length of immunity after booster shots. Using data for August from the United States, Britain, Israel, Spain and France, the mathematicians looked at the potential results if China adopted similar pandemic response strategies to those used in the selected countries. In August, most of these countries had presented higher vaccination rates than China, where 54 per cent of the eligible population were inoculated. These countries also had a higher natural immunity ratio, despite having lower population densities than China. The researchers estimated that China would have more than 637,155 daily confirmed cases if it went down the same pandemic strategy path as the US, which had an average of 150,098 daily confirmed cases towards the end of August. The report said China would have had 275,793 cases if it took the same approach as Britain and 454,198 cases if it followed France. “Our findings have raised a clear warning that, for the time being, we are not ready to embrace ‘opening-up’ strategies and rely solely on the hypothesis of herd immunity induced by vaccination advocated by certain Western countries,” the report said. However, the study did acknowledge the estimates were based on basic arithmetic calculations and that more sophisticated dynamic models were needed to study the evolution of the pandemic if travel restrictions were lifted. The researchers said China would need a range of preparations in place – including more efficient vaccination coverage and specific treatment, different levels of nonpharmaceutical interventions and more hospital beds – before it could safely transition to opening-up strategies.