Cost‐Effectiveness Analysis of Nirsevimab for Respiratory Syncytial Virus Disease Prevention in Newborns of Hong Kong

ABSTRACT Background Nirsevimab, a long‐acting monoclonal antibody, was shown to prevent respiratory syncytial virus (RSV) infections in newborns. We evaluated the cost‐effectiveness of nirsevimab strategies for newborns from the societal perspective in Hong Kong. Methods A Markov model was developed to simulate outcomes of four nirsevimab strategies in newborns: (1) year‐round, (2) seasonal, (3) catch‐up, and (4) no nirsevimab. Primary outcomes included RSV lower respiratory tract infections (LRTI) related events, direct and indirect costs, quality‐adjusted life year (QALY) loss, and incremental cost per QALY (ICER). Results In base‐case analysis, all strategies with nirsevimab reduced RSV–LRTI‐related events. The catch‐up group had the lowest QALY loss per 100,000 infants (38.82), followed by year‐round (45.71), seasonal (60.60), and no intervention groups (81.52). Three nirsevimab cost levels were examined: 10%, 25%, and 50% of the US cost. At 10% US cost (USD52), all strategies were cost‐saving versus no intervention. At 25% US cost (USD130), the ICER of the catch‐up group (vs. no intervention) was 141,925 USD/QALY. At 50% US cost (USD260), all nirsevimab strategies were not cost‐effective versus no intervention at a willingness‐to‐pay of 162,401 USD/QALY. Influential factors with thresholds were identified for RSV‐LRTI incidence, RSV‐related hospitalization and mortality, and nirsevimab effectiveness at the 25% US cost level (USD130). In probabilistic sensitivity analysis, the catch‐up and no intervention strategies were cost‐effective 100% of the time at 10% (USD52) and 50% (USD260) US cost, respectively. At 25% US cost (USD130), the catch‐up strategy was cost‐effective 58.56% of the time. Conclusions The cost‐effectiveness acceptance of nirsevimab was highly subject to drug cost and effectiveness of nirsevimab, RSV‐LRTI incidence, and RSV–LRTI‐related consequences.