BACKGROUND: There is often gender bias in access and provision of care. Women fall through the cracks of the healthcare system due to gender-biased norms and poorer socioeconomic status. METHODS: This study uses COVID-19 sex-disaggregated data from 133 countries. Using bootstrapping and imputation methods and heteroscedastic linear regression model, it investigates the effect of biological factors and gender norms on reported differences in male and female COVID-19 case and death rates. RESULTS: Gender norms are significant factors explaining such differences. Countries, where women experience more discrimination in families and have less access to resources, education and finance, report larger differences between male and female rates of COVID-19 cases and deaths. CONCLUSION: Women's lower access to healthcare due to social norms, financial and non-financial barriers may affect women's testing for COVID-19 and access to adequate care, and result in underreported female cases and deaths from COVID-19.