# **Introduction**

In all countries around the world, women live longer than men (Dattani and Rodés-Guirao 2023). There is well-established evidence of a gender mortality gap driven by a range of environmental, genetic, and cultural factors (Waldron 1985). The persistence of higher mortality for men than women has been documented with data typically drawn principally from high-income countries (Wu et al. 2021). But these patterns have also been shown in low-income regions of the world (de Walque and Filmer 2013).

Prior to the 1950s, disproportionately higher deaths of male than female infants were the main driver of the longer life expectancy of women, but more recently the elevated mortality of older men has driven the gender gap in life expectancy (Zarullia et al. 2021). The COVID19 pandemic exacerbated this gap as age-standardized excess death rates were higher for men than women in many countries (Peckham et al. 2020; UN 2022). The sex inequality in mortality grew in many high-income countries due to COVID-19, though in the US, this disparity has been characterized as modest, and mortality from the pandemic has not changed the “fundamental dynamic” of sex-mortality gaps (Nazmul et al. 2021; Danielsen et al. 2022). Likewise, for European countries, the difference in mortality by sex during the COVID-19 pandemic is similar to pre-pandemic patterns (Neilsen et al. 2021). In non-highincome settings, both COVID-19 and excess death age-mortality curves are flatter, only in part due to population structure (Demombynes et al. 2022). This suggests that the extent to which the gender gap in mortality increased likely differs across country income levels. In part due to the lack of data, previous detailed analysis of COVID-19 mortality patterns by age have combined both sexes, neglecting this well-established fact that mortality rates of men are higher than those of women, and that this might vary by country income level.

This study draws on recent data which were not available for earlier studies to examine the extent to which the gender gap in mortality shifted in high- and middle-income countries during the COVID-19 pandemic. Unfortunately, underdeveloped civil registration systems for reporting on male and female deaths limits data availability in low-income countries, a persistent limitation in the study of global population-level mortality patterns.

# **Methods**

# _Data sources_

We use the “Global excess deaths associated with COVID-19 (modelled estimates)” dataset (May 19, 2023 update), produced by WHO’s Technical Advisory Group (TAG) on COVID-19 mortality assessment. This dataset contains estimates of expected all-cause deaths, all-cause deaths (actual or predicted if actual was not available), and excess deaths by age-group and sex for 194 countries for 2020 and 2021. Expected all-cause deaths were forecasted using historic country-level monthly mortality data prior to the pandemic and serve as reference point in the absence of COVID-19. Excess deaths were computed as "the mortality above what would be expected based on the non-crisis mortality rate in the population of interest” by differencing actual/predicted all-cause deaths from expected all-cause deaths (World 2