Disparities in response to mRNA SARS-CoV-2 vaccines according to sex and age: A systematic review

Background The rapid development and distribution of mRNA COVID-19 vaccines has been essential in containing the SARS-CoV-2 epidemic around the globe. For ongoing and future immunization campaigns globally, there is a need to evaluate the impact of population demographics such as age and sex, on vaccine efficacy and safety.Methods This systematic review (PROSPERO ID CRD42023328245) conducted according to PRISMA guidelines evaluates the impact of age and sex on the safety and efficacy of the mRNA COVID-19 vaccinations administrated in 15 studies that were chosen according to strict criteria. The ROBIS tool was applied to evaluate the robustness and the quality of the studies included in the review.Results After screening, 15 studies satisfied the inclusion criteria. The results showed that the COVID-19 mRNA vaccines typically elicit robust immune responses, and that younger people have higher antibody levels. Comparing the sexes reveals that higher immunological responses were induced in females, and mild to moderate adverse effects (such as injection site discomfort, exhaustion, and headaches) were also more frequently reported in women. Despite these variations, COVID-19 vaccines have been found to be safe to use across diverse populations, which supports their extensive use in public health initiatives.Conclusion Our results suggests that tailored vaccination may achieve maximum effectiveness and better tolerability depending on age and sex. Currently study results are rarely stratified by age and sex and this is a deficit in clinical trial publications. More research is needed to elucidate the biological mechanisms underlying the variations in vaccine responses according to age and sex.