Gender inequalities in biomedical literature have been widely reported in authorship as well as the scarcity of results that are stratified by sex in the studies. We conducted a bibliometric review of articles on COVID-19 published in the main Spanish medical journals between April 2020 and May 2021. The purpose of this study was to analyse differences in authorship order and composition by sex and their evolution over time, as well as the frequency of sex-disaggregated empirical results and its relationship with the author sex in articles on COVID-19 in the main Spanish biomedical journals. We identified 914 articles and 4921 authors, 57.5% men and 42.5% women. Women accounted for 36.7% of first authors and for 33.7% of last authors. Monthly variation in authorship over the course of the pandemic indicates that women were always less likely to publish as first authors. Only 1.0% of the articles broke down empirical results by sex. Disaggregation of results by sex was significantly more frequent when women were first authors and when women were the majority in the authorship. It is important to make gender inequalities visible in scientific dissemination and to promote gender-sensitive research, which can help to reduce gender bias in clinical studies as well as to design public policies for post-pandemic recovery that are more gender-equitable.
Keywords: COVID-19; authorship; disaggregation by sex; gender; inequalities.