[Vaccine, 30 August 2024]

Background: Health Canada recently authorized the RSVpreF pregnancy vaccine and nirsevimab to protect infants against respiratory syncytial virus (RSV) disease.

Objective: Assess the cost-effectiveness of RSVpreF and nirsevimab programs in preventing RSV disease in infants, compared to a palivizumab program.

Methods: We used a static cohort model of a Canadian birth cohort during their first RSV season to estimate sequential incremental cost-effectiveness ratios (ICERs) in 2023 Canadian dollars per quality-adjusted life year (QALY) for nine strategies implemented over a one-year time period, from the health system and societal perspectives. Sensitivity and scenario analyses were conducted to explore the impact of uncertainties on the results.

Results: All-infants nirsevimab programs averted more RSV-related outcomes than year-round RSVpreF programs, with the most RSV cases averted in a seasonal nirsevimab program with catch-up. Assuming list prices for these immunizing agents, all-infants nirsevimab and year-round RSVpreF programs were never cost-effective, with ICERs far exceeding commonly used cost-effectiveness thresholds. Seasonal nirsevimab with catch-up for infants born outside the RSV season was a cost-effective program if prioritized for infants at moderate/high-risk (ICER <$28,000 per QALY) or those living in settings with higher RSV burden and healthcare costs, such as remote communities where transport would be complex (ICER of $5700 per QALY). Using a $50,000 per QALY threshold, an all-infants nirsevimab program could be optimal if nirsevimab is priced at <$110–190 per dose. A year-round RSVpreF for all pregnant women and pregnant people plus nirsevimab for infants at high-risk was optimal if nirsevimab is priced at >$110–190 per dose and RSVpreF priced at <$60–125 per dose.

Interpretation: Prophylactic interventions can substantially reduce RSV disease in infants, and more focused nirsevimab programs are the most cost-effective option at current product prices.