Safety, immunogenicity, and effectiveness of chikungunya vaccines in pregnant persons, children, and adolescents: a protocol for a living systematic review and meta-analysis

Background: Chikungunya virus significantly impacts public health, primarily affecting regions in Africa and the Americas (predominantly Latin America and the Caribbean). Despite the global spread of the virus and its clinical manifestations and complications in vulnerable populations such as children and pregnant persons, no widely available vaccine is currently available. With recent advancements in vaccine development, there is a need to systematically evaluate the emerging evidence on the safety, immunogenicity, and efficacy of chikungunya vaccine candidates. This protocol outlines a living systematic review designed to continuously assess the growing research on chikungunya vaccines, focusing on diverse populations, including children and pregnant persons. We aim to provide up-to-date evidence to inform public health decisions and vaccine recommendations as new data is available. Methods: Our objective is to carry out a living systematic review and meta-analysis through biweekly searches in medical databases and clinical trial registries, aiming to identify relevant chikungunya vaccines studies on pregnant individuals, children, and adolescents. Pairs of reviewers will independently screen studies, extract data, and assess the risk of bias. Clinical trials, quasi-experimental studies, and observational studies, including case reports, will be considered for inclusion. Main outcomes will include the safety, efficacy, and effectiveness of chikungunya vaccines in pregnant individuals (including neonatal outcomes), as well as in children and adolescents. Reactogenicity and immunogenicity will be considered as secondary outcomes. Paired meta-analyses, incorporating predefined subgroup and sensitivity analyses, will be performed. Evidence certainty will be assessed using the Grading of Recommendations Assessment, Development, and Evaluation (GRADE) approach. Discussion: This living systematic review and meta-analysis will continuously assess the safety, immunogenicity, and effectiveness of chikungunya vaccines in pregnant persons, children, and adolescents. Given the significant disease burden and potential complications in these populations, synthesizing emerging evidence is crucial for guiding immunization policies and clinical recommendations. By maintaining an updated analysis, this review will provide timely insights for public health agencies, researchers, and clinicians involved in vaccine implementation and maternal-child health. Study registration: Two protocols were registered in the International Prospective Register of Systematic Reviews database, CRD42024514513 and CRD42024516754.