Respiratory Syncytial Virus Vaccination Is Associated With Increased Odds of Preterm Birth.

Aim: To analyse whether respiratory syncytial virus (RSV) vaccination during pregnancy increases the odds of preterm birth.

Methods: A rapid review and meta-analysis was performed. The main outcome was the risk of preterm (gestational week less than 37) birth. A fixed-effects model was used to analyse pooled odds ratios (OR) with 95% confidence intervals (CI). Evidence certainty was assessed according to GRADE.

Results: We included six randomised controlled trials with 17 656 births and two observational studies with 3446 births. The odds for preterm birth were increased in the randomised studies (OR 1.17, CI 1.02-1.34). No evidence of a difference was seen in the observational studies (OR 0.93, CI 0.69-1.25). Combined, these showed increased odds for preterm birth (OR 1.13, CI 1.00-1.27). Evidence certainty was rated to be moderate. When restricted to market-approved vaccine, the odds seemed to be increased in RCTs (OR 1.21, CI 0.98-1.49).

Conclusion: Based on the available evidence, RSV vaccination seems to be associated with increased odds for preterm birth. RSV vaccination needs continuous population-level observational safety data monitoring on the perinatal outcomes during the early phases of vaccine rollouts to detect possible safety signals and further confirm the magnitude of the effect on preterm birth.