Objective: To model the dynamics of the COVID-19 pandemic including new VOCs and vaccines and estimate the cost-effectiveness of the vaccination program in Colombia.

Methods: We developed a SEIARHUDSq micro-simulation model through nine exhaustive and mutually exclusive states: susceptible, exposed, symptomatic-infected, asymptomatic-infected, recovered, hospitalized general ward, Intensive Care Unit, death, and sequela. SEIARHUDSq was run with data reported up to October 21, 2021, and adjusted as a system of differential equations based on epidemiological (cases, deaths, VOCs, vaccine effectiveness, etc.) and economic (vaccines prices and administration, direct medical costs of states, etc.) inputs obtained from national sources and systematic literature reviews. DALYs and ICERs showed the burden of COVID-19 and the cost-effectiveness of the vaccination program. Two scenarios, in addition to do-nothing, were modelled for infection rates (Beta) estimated by an agnostic model: 1) Beta=0.4 and 2) Beta=0.5, for 70 and 90% of vaccination coverages. The effect of the vaccines (Pfizer, Moderna, Sinovac, AstraZeneca, and Janssen) was assumed 14 after their application. Willingness-to-pay was set as one GDP per capita (US$5,376). We reported costs in American dollars (1$US=COP$3,702).

Results: In Do-nothing scenario the DALYs ranges between 2.3 and 2.4 million. By vaccinating the population, the burden of disease decreased to under 2.15 million DALYs. If 70% of the population were vaccinated, direct medical and vaccination costs (including administration) would be between US$2.1-2.4 billion for a Beta of 0.4-0.5, respectively (net costs). Costs would vary between US$2.3 and 2.4 billion at 90% simulated coverage. COVID-19 vaccination in Colombia have been cost-effective for Beta=0.4 scenario (ICER 70% coverage: US$995.5; ICER 90% coverage: US$1,837) and for Beta=0.5 (ICER 90% coverage: US$1,792). The scenario for Beta=0,5 (ICER 70% coverage) was dominated.

Conclusion: COVID-19 vaccination in Colombia, prioritizing elderly and population with comorbidities, has been highly cost-effective in most of the modeled scenarios.