How Well Do RSV Vaccines Work in Older People?

Three vaccines against respiratory syncytial virus–associated lower respiratory disease (RSV LRTD) have been approved: mRNA vaccine, adjuvanted protein subunit vaccine (RSVpreF3 OA), and unadjuvanted protein subunit (RSVpreF). How long does their protection last? Ison et al. assessed the efficacy of one dose or two doses (in consecutive seasons) of RSVpreF3 OA. In a randomized trial involving almost 25,000 participants (median age, 69), half received placebo and half received vaccine prior to season 1. Among vaccine recipients, half were randomized to vaccine and half to placebo prior to season 2. Over three seasons, efficacy of a single dose at preventing RSV-associated LRTD was 63% (having fallen from 83% in season 1 to 48% in season 3). …