OBJECTIVES: RSV is a major cause of respiratory illness in older adults. In 2023, two vaccines were authorized by Health Canada for prevention of RSV-LRTD among adults aged ≥60 years; another vaccine for adults is under regulatory review. We evaluated the potential public health impact of three vaccines for prevention of RSV-LRTD in older adults.

METHODS: A cohort model was employed to depict clinical and economic outcomes of RSV-LRTD over four years with use of Pfizer’s RSVpreF, GSK’s RSVpreF3, and Moderna’s mRNA-1345, respectively, versus no intervention among adults aged ≥60 years in Canada (N=9.6M). Clinical outcomes were projected (monthly) based on age, comorbidity profile (i.e., with vs. without chronic or immunocompromising conditions), RSV-LRTD rates (requiring hospitalization [H], emergency department [ED], or physician office/hospital outpatient care [PO/HO]), calendar month, case fatality rates (RSV-H only), and vaccination status (uptake: 60-74y, 48.3%; 75-99y, 65.4%; 50%/50% administered October/November of model year 1). Initial vaccine effectiveness and waning were derived from Phase III clinical trial data. Medical costs were generated based on cases and corresponding unit costs.

RESULTS: With no vaccine, 63,478 hospitalizations, 48,128 ED encounters, 565,681 PO/HO visits, and 6,590 RSV-related deaths are projected over four years. Pfizer’s RSVpreF would result in a 153,307-case reduction (RSV-H: 24,601; RSV-ED: 17,740; RSV-PO/HO: 110,965) and 2,646 fewer deaths; total medical care costs would be lower by $435.8M (RSV-H: $416.6M; RSV-ED: $5.8M; RSV-PO/HO: $13.4M). GSK’s RSVpreF3 would reduce cases by 119,818, deaths by 1,657, and medical care costs by $283.9M. Moderna’s mRNA-1345 would reduce cases by 98,488, deaths by 1,136, and medical care costs by $198.8M.

CONCLUSIONS: RSV vaccines have the potential to substantially reduce the clinical and economic burden of RSV-LRTD in older adults. Of the three vaccines, Pfizer’s RSVpreF would provide the greatest benefit due to its high year 2 efficacy and anticipated extended protection.