C25-06 Mathematical Modeling of Universal RSV Prevention in Colombia: Real-world Effectiveness on Wheezing and Long-term Asthma Projections Across 2.1 Million Births

Rationale Respiratory syncytial virus (RSV) infection in infancy causes recurrent wheezing and childhood asthma, yet population-level burden estimates integrating both outcomes remain limited in Latin America. Objective To quantify RSV-attributable recurrent wheezing and childhood asthma burden in Colombia and estimate preventable cases through universal nirsevimab immunization. Methods Population-based modeling of Colombian births 2022-2024 (n = 1,456,153). INSPIRE data: 27% infected with RSV before 6 months. Recurrent wheezing rates in RSV-infected children: 18·95% (year 1), 17·14% (year 2), 15·45% (year 3), 12·47% (year 4). Asthma at age 5: 20·75% in RSV-infected versus 15·50% in uninfected (RR 0·74, p = 0·01). Nirsevimab effectiveness from Chile (76·41%, coverage 97·1% = 74·2% population protection) applied to RSV→wheezing→asthma cascade. US validation: 76% RSV reduction, 27% all-cause wheezing. Costs: $191/episode, $180/year asthma. Results Across three cohorts, 393,161 RSV infections before 6 months generated 721,186 recurrent wheezing cases over 4 years (177,083 year 1; 203,345 year 2; 186,495 year 3; 154,263 year 4) and 81,581 asthma cases at age 5 years. Economic burden totaled $275·5 million for wheezing ($67·6M, $77·7M, $71·2M, $58·9M by year) plus $14·7 million annually for asthma. Modeling RSV infection prevention as interrupting the respiratory morbidity cascade, universal nirsevimab immunization preventing 291,725 (74·2%) RSV infections would avert 535,120 RSV-attributable wheezing cases (131,396 year 1; 150,882 year 2; 138,379 year 3; 114,463 year 4) and 60,534 asthma cases, with savings of $204·4 million in wheezing costs ($50·2M, $57·6M, $52·9M, $43·7M by year) plus $10·9 million annually in asthma, totaling $215 million. Direct US evidence measuring all-cause wheezing demonstrates 27% reduction with 47,812 year-1 cases prevented ($18 million savings). Conclusion RSV infection before 6 months drives over 720,000 wheezing cases and 81,000 asthma cases in Colombia. Universal nirsevimab could prevent 74% of RSV-attributable burden—535,000 wheezing cases and 60,000 asthma cases—with $215 million savings. Conservative estimates confirm substantial morbidity reduction. Benefits extend far beyond acute hospitalization to major reductions in chronic respiratory disease, providing strong evidence for universal RSV prevention policy. This abstract is funded by: None