Abstract

Objectives

Respiratory syncytial virus is known to cause severe bronchiolitis and pneumonia among infants. There are 2 main ways to protect infants from respiratory syncytial virus (RSV)-related diseases, namely, vaccination of pregnant women with recombinant subunit RSV pre-fusion F3 (RSVpreF) and prophylaxis of neonates/infants with nirsevimab. In 2024, both products were approved in Japan. We evaluated the cost-effectiveness of multiple immunization strategies for the protection of Japanese infants from RSV diseases by using nirsevimab and/or RSVpreF.

Methods

A decision tree with Markov model was adopted. Incremental cost-effectiveness ratio (ICER) from payers’ perspective was calculated. Variables used in the model were either calculated or extracted from literature. Costs per RSVpreF and nirsevimab vaccination was assumed to be at JPY23 948/US$160 and JPY45 000/US$300, respectively.

Results

Vaccination of pregnant women with RSVpreF strategies (seasonally or year-round), prophylaxis of infants with the nirsevimab strategy, and a combination of seasonally RSVpreF and nirsevimab strategies, all reduced disease treatment costs; however, the reduction could not offset the vaccination/prophylaxis cost. RSVpreF_year-round strategy and nirsevimab strategy were either extended or absolutely dominated by the other 2 strategies and were excluded from being considered as an option. The ICER of seasonal RSVpreF strategy was JPY3 227 850/US$21 519/quality-adjusted life-years (QALY), whereas the Combination strategy’s ICER was JPY23 236 084/US$154 907/QALY per QALY gained. One-way sensitivity analyses revealed that the probability of hospitalization, vaccination costs, and effectiveness of both products influence the ICER the most. The cost-effectiveness acceptance curve revealed that the curve reached 98.7% at a willingness to pay of JPY5 000 000/US$33 333 per QALY.

Conclusions

Only seasonal RSVpreF strategy is cost-effective under the JPY5 000 000/US$33 333 per QALY willingness-to-pay threshold.