A projection estimates that between 1.3 and 2.1 million people could die if China lifts its zero-COVID-19 approach.
The number of deaths is estimated, taking into account low vaccination and booster rates as well as a lack of hybrid immunity.
The risk analysis by Airfinity, a science information and analytics company, uses cumulative peak cases and deaths from the Omicron subvariant BA.1 wave in Hong Kong. This administrative region in China also took a zero-COVID approach during the first two years of the pandemic.
As a result, population immunity from infection was low, and so was the vaccination rate. Therefore, when the BA.1 subvariant reached the region in February, it caused a huge wave of infections and deaths, especially amongst the elderly.
The immunity levels across China's population are also low because people were vaccinated with locally produced Sinovac and Sinopharm vaccines, which provide less protection against infection and death, according to Airfinity's analysis.
Moreover, low booster rates and no immunity from infections leave the population more susceptible to severe disease.
Another study published in the preprint server medRxiv last week suggests that simultaneously reopening all China's provinces under current public health and social measures would lead to hospitalization demands that are 1.5-2.5 times of surge hospital capacity.
China has been implementing the zero-COVID policy since the beginning of the pandemic. Besides mass testing and closing off entire neighborhoods, people with COVID-19 or those who had close contact with them were forced to state quarantine facilities.
The approach caused unprecedented protests in the autocratic country with mass surveillance, tightly controlled media, and censored internet.
Earlier this month, Chinese health officials announced abandoning parts of the zero-COVID policy.