How do Recent Population-Level RSVpreF Vaccine-Impact Results from the United Kingdom Relate to Previously Reported Vaccine Effectiveness Results?

INTRODUCTION: Respiratory syncytial virus (RSV) is an important cause of hospitalizations among adults. Following bivalent respiratory syncytial virus prefusion F (RSVpreF) vaccine licensure and implementation, two studies have documented population-level reductions in RSV hospitalizations in the United Kingdom (UK), ranging from 30% to 62% in England and Scotland, respectively. Separately, vaccine effectiveness (VE) studies have been conducted in a number of settings. The question arises: Is there a relationship between these population-level reductions in RSV hospitalizations and real-world VE estimates from the first season post-implementation of bivalent RSVpreF, and do the impact findings reflect what would be expected from the VE estimates? METHODS: Publicly available estimates for end-of-season-1 (EOS1) bivalent RSVpreF VE against RSV-related hospitalization were identified. Using these VE estimates, the expected vaccine impact across all potential vaccine coverage values was calculated using the formula impact = VE * uptake. We additionally estimated expected VE based on the impact findings from the RDD analyses. RESULTS: Six real-world studies evaluating bivalent RSVpreF VE were identified from the United States, UK, and Denmark; they documented 67-91% bivalent RSVpreF VE against RSV-related hospitalizations. Calculated impact using these six VE estimates closely aligned with the measured results estimated from the UK analyses. VEs calculated in turn from impact estimates ranged from 91% [Scotland] to 76% [England], closely aligning with expected results. CONCLUSIONS: These early results indicate that the extent of expected population-level impact achieved can be reliably predicted from VE studies and national coverage data. Bivalent RSVpreF use can have a substantial public health and economic impact by reducing RSV-related hospitalizations, as seen in this initial UK vaccination program. Protection of older adults from severe RSV disease is off to a promising start and implementation efforts to boost vaccine uptake should be a priority for health care workers, public health practitioners, and policymakers.