Sex- and gender-related differences linked to SARS-CoV-2 infection among the participants in the web-based EPICOVID19 survey: the hormonal hypothesis

Objective To investigate sex- and gender-based differences linked to SARS-COV-2 infection and to explore the role of hormonal therapy (HT) in females. Study design Data from the self-administered, cross-sectional, web-based EPICOVID19 survey of 198,822 adults living in Italy who completed an online questionnaire during the first wave of the epidemic in Italy (April-May 2020) were analyzed. Main outcomes measures Multivariate binary logistic and multinomial regression models were respectively used to estimate the odds ratios (ORs) with 95% confidence intervals (CIs) for positive nasopharyngeal swab (NPS) test results and severe SARS-CoV-2 infection. Results The data from 6,873 participants (mean age 47.9 ± 14.1 years, 65.8% females) who had a known result from an NPS test were analyzed. According to the multivariate analysis, females had lower odds of a positive result from the NPS test (aOR 0.75, 95%CI 0.66–0.85) and of having a severe infection (aOR 0.46, 95%CI 0.37–0.57) than did their male counterparts. These differences were greater with decreasing age in both sexes. In addition, females aged ≥60 years receiving HT (N = 2,153, 47.6%) had a 46% lower probability of having a positive NPS test (aOR 0.54, 95%CI 0.36–0.80) than their same-aged peers who had never used HT; there were no differences in the younger age groups with respect to HT status. Conclusion Female sex was associated with an age-dependent lower risk of having a severe SARS-CoV-2 infection than their male counterparts. Age seemed to modify the relationship between HT status and infection: while the two were not related among younger participants, it was negative in the older ones. Future prospective studies are needed to elucidate the potential protective role sex hormones may play.