OBJECTIVES: This study assessed the public health and economic impact of annual dose of an adapted vaccine in Colombia.

METHODS: A combined Markov and decision tree model was used to estimate the economic and public health impact of vaccination strategies targeting various age groups in Colombia over a one-year time horizon. Age-stratified annual attack rates of infections, hospitalizations, deaths and vaccine coverage were informed by the literature and national public health surveillance data based on Omicron variant dominance period. Hospitalization and cost inputs were informed by a real world evidence study in Colombia using data from 2021 to 2022. Other age-stratified clinical, cost, and vaccine effectiveness parameters were informed by the literature. Costs were converted to USD using an exchange rate of COP 3,863/USD. Parameter uncertainty was examined through scenario and sensitivity analyses.

RESULTS: A vaccination strategy targeting individuals aged ≥65 years and the high-risk population aged 18-64 years was estimated to avert 313,981 symptomatic cases, 3,391 deaths, 5,609 hospitalizations, and 39,848 lost quality-adjusted life years (QALYs), translating into direct and societal cost savings of $75 million and $137 million, respectively. Expanding the vaccination strategy to target additional age groups increased public health and economic impact. For example, a strategy targeting individuals aged ≥50 years and the high-risk population aged 18-49 years increased the doses administered by 15% but also increased symptomatic cases averted by 15%, deaths averted by 5%, hospitalization averted by 16%, direct cost savings by 17%, and indirect cost savings by 21%. In sensitivity analysis, results were most sensitive to duration of protection of the vaccine, attack rates, symptomatic rates, and vaccine effectiveness.

CONCLUSIONS: A vaccination strategy targeting individuals aged ≥65 years and those aged 18-64 years at high risk yields substantial public health and economic gains annually, but expansion to additional age groups provides additional gains.