Social inequalities and full vaccination coverage at 24 months - 2017-2018 live birth cohort: National Vaccination...

To analyze social inequalities in vaccination coverage for the full immunization schedule with valid doses at 24 months of age, according to socioeconomic strata and family, maternal, and child characteristics.

This is a retrospective 2017-2018 live birth cohort in capitals, the Federal District, and 12 Brazilian cities, recruited in 2020-2021. Participants were followed up from birth using the vaccination cards, and there were no losses to follow-up. Guardians were interviewed and vaccination cards were photographed. Urban census tracts of the 39 cities were grouped into four strata by cluster analysis of average income, income >20 minimum wage, % literate individuals. The same number of census tracts were drawn from each stratum, and children from cohorts of interest were recruited until sample size was complete. The coverage of the full immunization schedule for each child was calculated considering only valid doses (date and interval between doses). Descriptive, stratified analysis, and Poisson regression were performed using the STATA 17.0 survey module.

A total of 37,801 children were included. Vaccination coverage was below 50% in all strata, with strata A and B as the lowest. The probability of having a full immunization schedule was lower from the second-born child onward, in families with intra-household crowding, and difficulties in accessing health services. Exclusive use of public services was associated with higher full coverage.

Vaccination coverage was lower in strata with better standards of living (A/B). Vaccination coverage by family, maternal, and individual factors vary between strata and it is not possible to establish a common pattern.