OBJECTIVES

Respiratory syncytial virus (RSV) is the leading cause of viral lower respiratory tract illness (LRTI) in young children, such as bronchiolitis or pneumonia. It is associated with significant morbidity, especially among infants. New prophylactic options are currently in late-development stages, notably nirsevimab, a monoclonal antibody developed as a passive immunization intervention for the prevention of RSV-LRTI. Understanding its potential health economic impact is important to define the intervention strategy of protecting all infants experiencing their first RSV season. The objective of this work is to explore the cost-effectiveness of nirsevimab in a US birth cohort compared to the current standard of practice, palivizumab, and to no intervention.

METHODS

A static Markov model was developed to estimate RSV-related events and costs in a birth cohort over the first RSV season, in the USA. By applying a cycle length of one month, the cohort was exposed to a differential risk of RSV, considering the incidence per age in month and density of RSV circulation reflecting seasonality. Extensive scenario analyses were performed on the different populations both in terms of age and risk, to identify the most cost-effective approaches.

RESULTS

Under current standard of practice, the model estimates 594,596 [537,116 – 617,780] medically-attended RSV-LRTIs over one season for an annual economic burden estimated at $1.3 billion [$1.0 – $1.6]. Nirsevimab allowed more than 50% reduction of cases considering a coverage rate of 76% and an efficacy of 70%. The most cost-effective approach was to target all infants, where the burden of disease was equally distributed between in-season and out-of-season births due to a seasonal effect. The best implementation approach was seasonal, given the window of protection provided by nirsevimab.

CONCLUSIONS

Nirsevimab can provide a cost-effective intervention if used as a seasonal, passive immunization strategy targeted on all infants experiencing their first RSV season.