Introducing the Concept of Small Vulnerable Newborns (SVN) as an Additional Endpoint to Evaluate Birth Outcomes in the Context of RSV Immunization Studies—A Commentary

Infection with respiratory syncytial virus (RSV) represents a substantial burden of disease, especially in children. While one vaccine (RSVpreF) has been recommended for administration in pregnant women, another one (RSVPreF3-Mat) has been discontinued in a Phase 3 study due to an increased incidence of preterm births in the study group. When comparing the studies related to these two vaccine candidates, the differences in preterm birth rates appear inconsistent. For a more differentiated evaluation of birth outcomes associated with maternal RSV vaccination, we recommend introducing the previously described concept of "small and vulnerable newborns."