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Sex differences in COVID-19 infection and mortality in Hong Kong
Alexandra H T Law1, Jessica Y Wong1, Yun Lin1
1World Health Organization Collaborating Centre for Infectious Disease Epidemiology and Control, School of Public Health, The University of Hong Kong, Pokfulam, Hong Kong Special Administrative Region, China.
Background:
Sex differences in COVID-19 mortality have been widely reported. We examined infection and mortality patterns by sex across multiple COVID-19 epidemic waves in Hong Kong and investigated the contribution of vaccination status and pre-existing chronic conditions to the observed sex differences.
Methods:
We estimated age- and sex-specific incidence risks of cases, hospitalizations, and deaths per 100,000 population. Case-hospitalization risks, case-fatality risks (CFRs), and hospital-fatality risks were estimated with and without adjustment for vaccination status and pre-existing chronic conditions. We compared the sex ratio of COVID-19 mortality with that of other respiratory diseases during the pre-pandemic period (2000-2019).
Results:
Hong Kong recorded 2,876,110 COVID-19 cases and 12,737 deaths from January 2020 to January 2023, with males comprising 45.8% of cases and 59.1% of deaths. Infection risks were similar between sexes across all eight epidemic waves. Males consistently had higher CFRs and hospital-fatality risks in every wave. The elevated male mortality risk persisted after adjustment for vaccination and chronic comorbidities. The male-to-female ratio of COVID-19 mortality mirrored that observed for other respiratory diseases in the pre-pandemic period.
Conclusions:
While SARS-CoV-2 infection risks were similar by sex, males experienced significantly higher mortality risks that remained after adjusting for known risk factors. COVID-19 shows a similar male-to-female mortality ratio to other respiratory diseases.
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