The efficacy of vaccination against respiratory syncytial virus across priority population subgroups

Abstract Background Respiratory syncytial virus (RSV) has recently become a vaccine-preventable disease as two vaccines have been approved for use and a third one is likely to become available by the end of the year. National Immunization Technical Advisory Groups as well as scientific societies across the world have issued recommendations on RSV vaccination that differ in respect to the identification of the target group. The latter has been identified in respect to age or underlying medical conditions mostly according to epidemiological data. In order to strengthen the evidence basis for future decisions, we performed a stratified meta-analysis of efficacy data considering all the three RSV vaccines currently or soon available. Methods We searched Randomized Controlled Trials (RCTs) assessing the efficacy of RSV vaccines in terms of reduction of RSV-related Lower Respiratory Tract Infection (LRTI). The research was conducted on PubMed and clinicaltrial.gov. The extraction of relevant data was stratified by pre-defined age groups (60-69, 70-79, 80+) and presence of underlying conditions increasing the risk for RSV. Results Three RCTs, one for each of the three vaccines, were considered for the quantitative analysis. Considering the overall 60+ population, the efficacy of RSV vaccines was 78% (95%CI 76-86%) in preventing LRTI. Considering the different age groups (60-69, 70-79, 80+), efficacy was respectively 72% (95%CI 53-84%), 90% (95%CI 66-97%) and 57% (95%CI 0-93%). The efficacy in healthy people and those with at least one underlying condition was similar, namely 77% (95%CI 60-87%) and 78% (95%CI 50-90%). Conclusions The available evidence shows the efficacy of RSV vaccines in reducing LRTI with no differences across different priority groups. Further studies may contribute to better understanding if the efficacy may change according to individual characteristics, that could be highly relevant in the decision-making process. Key messages • The available evidence from RCTs shows the efficacy of RSV vaccines in reducing LRTI with no differences across different priority groups. • National recommendations on RSV vaccination can be further informed for future studies investigating RSV vaccines efficacy across different subgroups.