Is Colombia reaching the goals on infant immunization coverage? A quantitative survey from 80 municipalities

This study aimed to evaluate the coverage of the Colombian Expanded Program on Immunization among children less than 6years old, to evaluate the timeliness of immunization, to assess the coverage of newly introduced vaccines, and to identify factors associated with lack of immunization.

We conducted a cross-sectional survey in 80 municipalities of Colombia, using a two-stage cluster random sampling. We attempted to contact all children less than 6years old living in the sampled blocks, and asked their caregivers to provide immunization record cards. We also collected basic sociodemographic information.

We reached 81% of the attempted household contacts, identifying 18,232 children; of them, 14,805 (83%) had an immunization record card. Coverage for traditional vaccines was above 90%: BCG (tuberculosis) 95.7% (95%CI: 95.1-96.4), pentavalent vaccine 93.3% (92.4-94.3), MMR (measles, mumps, rubella) initial dose 94.5% (93.5-95.6); but it was lower for recently introduced vaccines: rotavirus 80% (77.8-82.1), influenza 48.4% (45.9-50.8). Results for timely vaccination were not equally successful: pentavalent vaccine 44.2% (41.4-47.1), MMR initial dose 71.2% (68.9-73.4). Mother's education was significantly associated with higher immunization odds. Older age, a greater number of siblings, low socioeconomic status, and not having health insurance were significantly associated with lower immunization odds. There was significant heterogeneity in immunization rates by municipality across the country.

Although absolute immunization coverage for traditional vaccines met the goal of 90% for the 80 municipalities combined, disparities in coverage across municipalities, delayed immunization, and decline of coverage with age, are common problems in Colombia that may result in reduced protection. Newly introduced vaccines require additional efforts to reach the goal. These results highlight the association of health inequities with low immunization coverage and delayed immunization. Identification of vulnerable populations and their missed opportunities for vaccination may help to improve the reach of immunization programs.