China’s unexpected easing of severe COVID-19 restrictions might lead to a spike in cases and over a million deaths by 2023. (IHME), according to fresh predictions from the American Institute of Health Metrics and Evaluation.

The association predicted that cases in China would peak around April 1 and surpass 322,000 deaths. By then, a third of China’s population will be sick, according to Christopher Murray, director of IHME.

China’s national health authority has not reported any official COVID deaths since the lifting of COVID restrictions. The last official deaths were reported on Dec. 3.

Total pandemic fatalities stand at 5,235.

China lifted some of the world’s toughest COVID restrictions in December after unprecedented public protests and is now experiencing a spike in infections, with fears COVID could sweep across its 1.4 billion population during next month’s Lunar New Year holiday.

“Nobody thought they would stick to zero-COVID as long as they did,” Murray said on Friday when the IHME projections were released online.

China’s zero-COVID policy may have been effective at keeping earlier variants of the virus at bay, but the high transmissibility of Omicron variants made it impossible to sustain, he said.

The independent modeling group at the University of Washington in Seattle, which has been relied on by governments and companies throughout the pandemic, drew on provincial data and information from a recent Omicron outbreak in Hong Kong.

“China has since the original Wuhan outbreak barely reported any deaths. That is why we looked to Hong Kong to get an idea of the infection fatality rate,” Murray said.

For its forecasts, IHME also uses information on vaccination rates provided by the Chinese government as well as assumptions on how various provinces will respond as infection rates increase.

Other experts expect some 60% of China’s population will eventually be infected, with a peak expected in January, hitting vulnerable populations, such as the elderly and those with pre-existing conditions, the hardest.

Key concerns include China’s large pool of susceptible individuals, the use of less effective vaccines and low vaccine coverage among those 80 and older, who are at greatest risk of severe disease.