Excess All-Cause Mortality in China After Ending the Zero COVID Policy.

Importance: In China, the implementation of stringent mitigation measures kept COVID-19 incidence and excess mortality low during the first years of the pandemic. However, China's decision to end its dynamic zero COVID policy (a proactive strategy that deploys mass testing and strict quarantine measures to stamp out any outbreak before it can spread) in December 2022 resulted in a surge in COVID-19 incidence and hospitalizations. Despite worldwide attention given to this event, the actual impact of this sudden shift in policy on population mortality has not been empirically estimated. Objective: To assess the association of the sudden shift in China's dynamic zero COVID policy with mortality using empirical and syndromic surveillance data. Design, Setting, and Participants: This cohort study analyzed published obituary data from 3 universities in China (2 in Beijing and 1 in Heilongjiang) and search engine data from the Baidu index (BI; weighted frequency of unique searches for a given keyword relative to the total search volume on the Baidu search engine) in each region of China from January 1, 2016, to January 31, 2023. Using an interrupted time-series design, analyses estimated the relative change in mortality among individuals 30 years and older in the universities and the change in BI for mortality-related terms in each region of China from December 2022 to January 2023. Analysis revealed a strong correlation between Baidu searches for mortality-related keywords and actual mortality burden. Using this correlation, the relative increase in mortality in Beijing and Heilongjiang was extrapolated to the rest of China, and region-specific excess mortality was calculated by multiplying the proportional increase in mortality by the number of expected deaths. Data analysis was performed from February 10, 2023, to March 5, 2023. Exposure: The end to the dynamic zero COVID policy in December 2022 in China. Main Outcomes and Measures: Monthly all-cause mortality by region. Results: An estimated 1.87 million (95% CI, 0.71 million-4.43 million; 1.33 per 1000 population) excess deaths occurred among individuals 30 years and older in China during the first 2 months after the end of the zero COVID policy. Excess deaths predominantly occurred among older individuals and were observed across all provinces in mainland China except Tibet. Conclusions and Relevance: In this cohort study of the population in China, the sudden lifting of the zero COVID policy was associated with significant increases in all-cause mortality. These findings provide valuable insights for policy makers and public health experts and are important for understanding how the sudden propagation of COVID-19 across a population may be associated with population mortality.