Sex Differences in Excess Mortality During the COVID-19 Pandemic

BackgroundThe COVID-19 pandemic was a significant global mortality shock. In addition to baseline differences in mortality risk, males often face a survival disadvantage in crisis situations such as famines and epidemics. Although many countries have reported higher numbers of male COVID-19 deaths, the evolution of sex differences in mortality over the course of the pandemic, and how these differences compare using both relative (accounting for higher male baseline mortality) and absolute measures remains underexplored. MethodsWe examined sex differences in excess mortality from March 2020 to July 2023 using data from 33 countries in the Short-Term Mortality Fluctuations dataset. We estimate both absolute (male excess mortality - female excess mortality) and relative (male P-score - female P-score) sex differences in COVID-related mortality. We analysed the sex gap monthly and across three pandemic phases: pre-vaccine, post-vaccine, and endemic. ResultsIn most countries, absolute male excess mortality exceeded that of females during the pre-vaccine phase of the pandemic. While the overall male disadvantage in total excess deaths gradually declined throughout the pandemic, it remained more pronounced in countries with delayed mortality peaks. The evidence for relative male disadvantage was weaker overall, and this gap further narrowed during the endemic phase. In some contexts, such as Nordic countries, women even experienced higher relative excess mortality later in the pandemic. Sex differences in absolute excess mortality tended to grow with age, but there was no clear pattern in the relative sex differences across age groups. ConclusionsWhile previous research has highlighted a male disadvantage in COVID-19 mortality based on absolute death counts, our study shows that this pattern was concentrated in the pre-vaccine phase and declined over time. Relative increases in mortality were often similar between sexes and, in some cases, greater among women. These findings suggest that sex differences in COVID-19 mortality were more varied than commonly assumed and underscore the importance of using both absolute and relative measures to assess the impact of health crises on population subgroups. Finally, our results suggest that COVID-19 did not produce lasting shifts in pre-pandemic sex differences in mortality.