OBJECTIVES. Both RSVpreF maternal vaccine and nirsevimab are authorised in Singapore to protect infants against lower respiratory tract illness due to respiratory syncytial virus (RSV-LRTI); however, an official immunisation programme has yet to be established. We evaluated the cost-effectiveness of a complementary approach (CA; RSVpreF use among pregnant women, nirsevimab only used among infants not yet protected) and, alternatively, nirsevimab alone (NA), compared to no intervention (NI) to prevent RSV-LRTI among infants in Singapore.
METHODS. A cohort model was developed to evaluate RSV-LRTI clinical outcomes (cases, deaths, quality-adjusted life-years [QALYs]) and economic costs (medical care, intervention, indirect [work-loss]) among infants aged <1 year (n=33,614). Outcomes among women vaccinated during pregnancy were also considered. RSV-LRTI cases were characterized by healthcare setting (hospital, primary care office [PC]). RSVpreF price was 202.64 Singapore dollars (SGD), reflective of the economically justifiable price associated with use of RSVpreF alone versus NI at a willingness-to-pay threshold of 121,162 SGD (Singapore’s gross domestic product per capita). Nirsevimab price was SGD 450. Uptake for RSVpreF and nirsevimab was 80% among eligible pregnant women and infants, respectively; for CA, infants protected via RSVpreF were not eligible for nirsevimab.
RESULTS. With NI, there were 781 hospitalizations and 2,201 PC encounters among infants; QALYs were 977,435. Total associated costs were SGD 7.7 million (M; medical care: SGD 5.3M, indirect: SGD 2.4M).
With NA, nirsevimab was administered to 26,888 infants, preventing 362 hospitalizations, 1,063 PC encounters, and yielding 45 additional QALYs. Total costs increased by SGD 8.4M (medical care: SGD -2.4M, intervention: SGD 11.9M, indirect: SGD -1.1M) compared to NI, yielding an incremental cost-effectiveness ratio (ICER) of SGD 321,711/QALY gained.
CA protected 32,682 infants (RSVpreF: 26,297; nirsevimab: 6,385), preventing 423 hospitalizations (infants: 410; mothers: 13), 1,679 PC encounters (infants: 923; mothers: 756), and yielding an additional 51 QALYs (infants: 46; mothers: 4) compared to NI. Total costs increased by SGD 3.0M (medical care: SGD -2.9M, intervention: SGD 8.2M, indirect: SGD -2.3M). The ICER for CA (including infant and maternal outcomes) versus NI was SGD 98,482/QALY gained.
CONCLUSION. A complementary strategy of maternal RSVpreF with nirsevimab for infants not yet protected would yield fewer hospitalizations and substantially reduce the economic burden of RSV-LRTI compared to nirsevimab alone, representing a more cost-effective use of resources in Singapore. The benefits of a complementary approach increase when considering RSVpreF protection conferred on mothers. Singapore’s strong antenatal care and high maternal vaccine uptake make this possible.