Objective: We evaluated the coverages of the expanded program of immunization in children under 6 years old for 2021.

Methods: We conducted a cross-sectional survey from October to November of 2021, in poor municipality of Colombia (73,653 inhabitants, 5,796 <6 year) mainly affected by the armed conflict. A two-stage cluster sampling with a precision of 5.5% and a design effect of 2 was performed. We considered a non-response rate of 20%. In each household, we determined age-appropriate routine antigen coverage for children <6 year of age based on vaccination card. Basic sociodemographic data from household surveys of caregivers of the children were gathered. Multivariate regression analysis was conducted to show timely-vaccine coverages key drivers.

Results: Overall coverage of most biologics at 18 months of age was >94%, based on vaccination cards of 175 children <6 years old (86.2% of all surveyed).

Vaccination absolute coverages for yellow fever and second doses of influenza, routine antigen boosters (first of MMR [measles, mumps, rubella] and second boosters of polio and DPT) ranges between 80-84%. Three biologics (BCG, hepatitis B, rotavirus) had age-appropriate timely vaccination coverages between 90-94%. Most vaccine timely coverage were between 74.1-89.7% (pneumococcal [first and third doses]; pentavalent, polio, and MMR [first and second doses]; DPT and polio boosters). The second dose of pneumococcal vaccine and the third of polio and pentavalent showed coverages from 62.7-64.8%. Lowest timely vaccination coverages were yellow fever (3.4%) and influenza (46.8% for first and 26.8% for second dosage). Mother’s education and birth order were significantly associated with higher timely immunization odds.

Conclusion: Our findings highlight the need for concerted efforts to improve timely routine immunization coverage in a post-conflict and pandemic scenario, especially for yellow fever and influenza vaccines. Low coverages for several vaccines were potentially explained for vaccine shortages.