Estimating the potential public health and economic impact of vaccination strategies with an adapted vaccine in Colombia using a combined Markov-decision tree model.

Background: Using adapted COVID-19 vaccines targeting current variants in circulation is necessary for addressing the dynamic evolution of the SARS-CoV-2 virus and protecting against emerging variants. This study evaluated the impact of various vaccination strategies with an adapted vaccine in Colombia.

Research design and methods: Using a previously published combined Markov-decision tree model adapted for the Colombia context, this study estimated the outcomes of different vaccination strategies targeting various age and risk groups. The model used age-specific epidemiology, clinical, cost, and quality of life inputs derived from the published literature and national surveillance data. Scenario and sensitivity analyses were conducted to assess uncertainty.

Results: Compared to no vaccination, the vaccination strategy targeting older adults aged ≥65 years and the high-risk population was estimated to prevent 306,460 symptomatic cases, 5,200 hospitalizations, 3,381 deaths, and 39,454 lost QALYs, translating to total direct and societal cost savings of USD 70,840,305 and USD 128,918,995, respectively. These gains were further increased by expanding vaccination to additional age groups. Results were most sensitive to parameters for the attack rate and duration of protection.

Conclusions: Implementing vaccination strategies targeting a broader age range with an adapted vaccine would result in considerable health and economic benefits in Colombia.