# Side Effects Associated With Respiratory Syncytial Virus Prefusion F (RSVpreF) Maternal Vaccination: A Scoping Review

## TL;DR

This review examines the safety of a maternal RSV vaccine, finding mostly mild side effects but highlighting the need for more research on potential risks like pregnancy-related hypertension.

## Contribution

The study provides a comprehensive overview of maternal safety data gaps and potential side effects of the RSVpreF vaccine.

## Key findings

- The RSVpreF vaccine is generally well tolerated with mild-to-moderate injection site reactions.
- Adverse events like preeclampsia and gestational hypertension were inconsistently reported.
- A possible link to hypertensive disorders of pregnancy was suggested but remains inconclusive.

## Abstract

Respiratory syncytial virus (RSV) is a leading cause of lower respiratory tract infections (LRTIs), with significant morbidity and mortality in infants. In August 2023, the Pfizer RSVpreF (respiratory syncytial virus prefusion F) vaccine was approved in the United States for maternal immunization, aiming to reduce RSV-related illness in neonates. The vaccine has proven efficacy in preventing severe LRTI in infants. However, limited research exists on its potential side effects, particularly on maternal health outcomes. This scoping review aimed to assess the extent and type of evidence available regarding safety and maternal side effects of the Pfizer RSVpreF vaccine when administered during pregnancy. A systematic search was conducted across six databases, including Ovid MEDLINE, Embase, CINAHL (Cumulative Index to Nursing and Allied Health Literature), Cochrane Central, Web of Science, and ClinicalTrials.gov, for peer-reviewed studies published between January 2020 and September 2024. Studies focusing on maternal outcomes following RSVpreF vaccine administration in pregnancy were included. Data extraction and analysis were performed following the Joanna Briggs Institute (JBI) methodology for scoping reviews. Of 1,259 initially identified studies, five met the inclusion criteria. The studies, spanning 2020-2024, included randomized controlled trials and a retrospective cohort study, primarily regarding high-income populations. Across the studies, findings indicate that the RSVpreF vaccine is generally well tolerated, with the most common side effects being mild-to-moderate local injection site reactions. Adverse events, including preeclampsia and gestational hypertension, were reported inconsistently across studies. A recent cohort study suggested a possible association between vaccine administration and hypertensive disorders of pregnancy (HDP), though findings remain inconclusive. Overall, the Pfizer RSVpreF vaccine appears to be well tolerated in pregnant women, but gaps in maternal safety data warrant further research. Future studies should prioritize high-risk patients and underrepresented populations, long-term maternal health outcomes, and potential associations with hypertensive disorders to ensure comprehensive vaccine safety and equitable access.