JMIR Publications

ABSTRACT

Background:

Respiratory syncytial virus (RSV) is a leading cause of lower respiratory tract disease (LRTD) in infants, with the highest burden in the first six months of life. Maternal immunization with the bivalent (RSV-A/B) pre-fusion F protein subunit vaccine (RSVpreF, ABRYSVO®) is a recently recommended strategy for preventing RSV-related outcomes in infants.

Objective:

This living systematic review (LSR) and meta-analysis (MA) will synthesize emerging post-licensure data on the efficacy/effectiveness and immunogenicity of the RSVpreF vaccine in real-world settings.

Methods:

We will conduct a LSR-MA following Cochrane methods and PRISMA‑P guidance. We will include randomized clinical trials and post‑licensure real‑world studies (e.g., cohort, case‑control, test‑negative, quasi‑experimental). Primary objectives are evaluation of vaccine efficacy and effectiveness (VE) in preventing RSV-specific and all-cause respiratory disease, and immunogenicity in infants and pregnant individuals. VE outcomes include RSV laboratory‑confirmed infection, RSV acute respiratory illness (ARI), RSV LRTD, RSV hospitalization, RSV complications (including secondary bacterial infection, respiratory failure, multiorgan failure, and death), all‑cause LRTD, all-cause LRTD hospitalization, and antibiotic use in infants with RSV infection. Immunogenicity outcomes include maternal neutralizing antibody titers (RSV‑A/B), maternal‑infant transfer ratios, infant titers at birth and over time, and RSV viral load. We will search MEDLINE, Embase, Cochrane Library, LILACS, SCI‑Expanded, CNKI/CBM/CSDC, clinical‑trial registries, and public health agency reports (e.g., CDC, UKHSA) from January 2023 onwards, with no language restrictions, updating at least monthly. Two reviewers will independently select studies, extract data (REDCap), and assess risk of bias (RoB 2 for RCTs; ROBINS‑I for non‑randomized studies). Where possible, adjusted estimates will be standardized to vaccine efficacy/effectiveness estimates. Certainty will be graded with the GRADE system. Ethics approval is not required.

Results:

These will be disseminated through peer‑reviewed publications, conferences, and an interactive dashboard with real‑time meta‑analyses. Data collection has already started. At present, 10 articles have been included.

Conclusions:

This LSR-MA provides a comprehensive synthesis of the expanding evidence on maternal RSVpreF VE, supporting timely interpretation of emerging real-world data with robust methodological quality. Clinical Trial: This protocol is registered in PROSPERO under CRD420251077829.