Sex-disaggregated effectiveness data reporting in COVID-19 vaccine research: a systematic review

Abstract

Background Sex and gender are believed to influence vaccine response. Yet, the relationship between sex and gender and COVID-19 vaccine efficacy is poorly understood and remains under-investigated. Methods We conducted a systematic review to determine whether and to what extent post-approval COVID-19 vaccine effectiveness (VE) studies report sex-disaggregated VE data. We searched four publication and pre-publication databases and additional grey literature sources for relevant published/preprint studies released between 1 January 2020 and 1 October 2021 (i.e., pre-Omicron era). We included observational studies providing VE estimates for one or more licensed/approved COVID-19 vaccines and including both males and females. Two reviewers independently assessed study eligibility, extracted data, and assessed risk-of-bias through a modified version of Cochrane’s ROBINS-I tool. A qualitative data synthesis was performed. Results Here we show that, among 240 eligible publications, 68 (28.3%) do not report the sex distribution among participants. Only 21/240 (8.8%) studies provide sex-disaggregated VE estimates, and high between-study heterogeneity regarding design, target population, outcomes, and vaccine type/timing prevent the assessment of sex in determining COVID-19 VE across studies. Conclusions Our findings indicate that few COVID-19 vaccine research publications account for sex. Improved adherence to recommended reporting guidelines will ensure that the evidence generated can be used to better understand the relationship between sex and gender and VE.

Assessing the real-world effectiveness of five SARS-CoV-2 vaccines in a cohort of Mexican pensioners: a nationwide nested test-negative design study

“…For example, one systematic review found that only 8.8% of post-approval evaluations provided such results. 38 These findings are supported by another review, which showed that only 24% of experimental and observational studies of COVID-19 VE reported sex-stratified primary outcome data. 37 The heterogeneity of study populations and approaches to estimating VE, and the variety of vaccines evaluated, prevented authors from such studies meta-analyzing VE estimates.…”

COVID-19 Vaccination Effectiveness in the General Population of an Italian Province: Two Years of Follow-Up

“…However, no significant differences in vaccine effectiveness were observed for all outcomes across genders, as previously reported by other studies [ 62 , 63 ], with a similar dose–response trend for both genders. The need for gender-disaggregated data on the effectiveness and safety of COVID-19 vaccines has been highlighted [ 63 , 64 , 65 ], with consideration of the higher levels of vaccine hesitancy found among females across several surveys [ 66 ].…”

Enabling preprint discovery, evaluation, and analysis with Europe PMC

“…As a result, Europe PMC adoption as a search engine for preprints in systematic reviews of the research literature has been referenced by numerous studies [62][63][64][65][66][67][68][69][70][71].…”

“…Systematic reviewers can export all or a selection of search results in various data formats including XML and CSV. As a result, Europe PMC adoption as a search engine for preprints in systematic reviews of the research literature has been referenced by numerous studies [62][63][64][65][66][67][68][69][70][71].…”