Sex differences in COVID-19 infection and mortality in Hong Kong

BackgroundVariation in COVID-19 mortality rates by sex could have several explanations. We aimed to determine sex differences in infection and mortality patterns across different COVID-19 epidemics in Hong Kong, and to evaluate potential hypotheses. MethodsWe estimated age- and sex-specific incidence rates of cases, hospitalizations, and deaths per 100,000 population. Case-hospitalization, case-fatality risks (CFRs), and hospital-fatality risks of the COVID-19 pandemic were also estimated. Adjusted and unadjusted risks were estimated and compared to explore the relationships between mortality and health-related variables. We also explored the sex ratio of COVID-19 mortality rates of respiratory diseases from 2000 to 2019. ResultsHong Kong recorded 2876110 COVID-19 cases and 12737 deaths between January 2020 and January 2023, with 1317368 cases (45.8%) and 7523 (59.1%) fatal cases occurring in males. The incidence rate of cases was similar by sex across waves. The CFRs and hospital-fatality risks were higher in men across all waves. Males had a significantly higher mortality risk after adjusting for sex, COVID-19 vaccination status, and pre-existing chronic diseases. The ratio of COVID-19 mortality rates in men versus women from 2020 to 2023 was similar to the mortality ratio for other respiratory diseases in the pre-pandemic period. ConclusionsWhile infection rates were similar for males and females, males experienced higher mortality risks even after adjusting for differences in other known risk factors. COVID-19 shares a similar sex ratio of mortality with respiratory diseases excluding COVID-19.