Presentation (CTI)

OBJECTIVES: Respiratory syncytial virus (RSV) is a major driver of severe respiratory illness and death in young children globally. Recently, two effective preventive options have emerged: immunizing pregnant women with an RSV vaccine or administering nirsevimab, a single-dose monoclonal antibody, directly to infants. This study evaluates whether universal nirsevimab use in infants is cost-effective relative to maternal RSV vaccination within the Brazilian health system.
METHODS: Using a decision-tree model, we simulated a cohort of 2.5 million Brazilian newborns over one year, adopting a public health system (Sistema Único de Saúde—SUS) perspective. Key outcomes were RSV infections, hospitalizations, deaths, and disability-adjusted life years (DALYs). Local health information systems, published evidence, and proposed market prices (nirsevimab: USD 255.15; maternal vaccine: USD 39.08) informed model inputs. Both strategies assumed 50% coverage. One-way and probabilistic sensitivity analyses tested parameter uncertainty.
RESULTS: Compared with maternal immunization, nirsevimab would avert an additional 13,703 RSV cases, 2,964 hospitalizations, and 23 deaths per year, leading to 485 fewer DALYs. However, its total costs were nearly five times higher (USD 362.3 million vs. USD 76.3 million). The resulting incremental cost-effectiveness ratio (ICER) was USD 589,130 per DALY averted, far above Brazil's willingness-to-pay threshold (USD 8,016). No sensitivity analysis scenario made nirsevimab cost-effective. Achieving cost-effectiveness would require an 83% reduction in its current price.
CONCLUSIONS: While nirsevimab offers superior health benefits, its current price prevents cost-effective use in Brazil. Marked price reductions are essential for feasible and long-term public adoption. These results carry important lessons for other middle-income nations considering similar RSV immunization programs.