What does this research mean for the field?

In 2023, MMR vaccination coverage among 1-year-old children in Brazil was below the target levels set by the Programa Nacional de Imunizações, with significant dropout rates for the 2nd dose, increasing the risk of measles reintroduction. Novelty: ClaimNovelty.CONFIRMATORY. Consensus alignment: ConsensusAlignment.CHALLENGES_CONSENSUS.

What question did this study set out to answer?

This study aims to assess adherence to the 1st and 2nd doses of the MMR vaccine in 1-year-old children across different regions of Brazil, focusing on implications for public health.

March 17, 2026Open Access

MMR Vaccination Coverage in 1-Year-Old Children in Brazil: Analysis of Adherence to the 1st and 2nd Doses and Risk of Measles Re-Emergence Based on the Anuário Vacinabr 2025

Key Points

This study aims to assess adherence to the 1st and 2nd doses of the MMR vaccine in 1-year-old children across different regions of Brazil, focusing on implications for public health.
Descriptive analysis based on data from Anuário VacinaBR 2025
Assessment of vaccination coverage in five macro-regions of Brazil
Calculation of dropout rates between the 1st and 2nd MMR doses
Comparison of coverage rates with the 95% target set by Programa Nacional de Imunizações in 2023.
None of the evaluated states met the 95% target for complete vaccination coverage in 2023.
Tocantins had the highest 1st dose rate at 95.6%, but only 47.9% for the 2nd dose.
Mato Grosso do Sul showed a significant decline in 2nd dose coverage from 100.9% to 37.8%.
Overall, low coverage and high dropout rates indicate a risk of measles reintroduction, especially in vulnerable regions.

Abstract

The MMR vaccine protects against measles, mumps and rubella—vaccine-preventable diseases with public health impact. Despite measles elimination in Brazil in 2016, declining vaccination coverage and abandonment of the 2nd dose have contributed to the emergence of outbreaks, undermining herd immunity. This study aims to analyze, based on 2023 data, adherence to the 1st and 2nd doses of MMR in 1-year-old children in Brazil, emphasizing regional differences and the risk of measles reintroduction. Descriptive study based on the Anuário VacinaBR 2025. Coverage of the 1st and 2nd MMR doses in 1-year-old children was analyzed in five states representing Brazil’s macro-regions: Tocantins, Maranhão, Mato Grosso do Sul, Rio de Janeiro and Rio Grande do Sul. Dropout rates were calculated by the difference between doses. The year 2023 was selected because it provides current and disaggregated data, enabling precise regional analyses. Results were compared with the 95% target defined by the Programa Nacional de Imunizações (PNI). In 2023, none of the states evaluated reached the target coverage for the complete schedule. Tocantins recorded 95.6% for the 1st dose and 47.9% for the 2nd, with a 47.7% dropout. Maranhão recorded 81.4% and 33.8%, respectively. In Rio de Janeiro, coverage was 70.1% and 36.9%. Mato Grosso do Sul showed the greatest decline (100.9% to 37.8%), with 63.1% dropout. Rio Grande do Sul, despite the best performance, remained below target: 94.2% for the 1st dose and 64.4% for the 2nd. There was good initial adherence followed by a marked drop in the 2nd dose, especially in the North, Northeast and Center-West regions. Low MMR coverage, combined with high dropout, exposes Brazil to the risk of measles reintroduction, especially in regions with structural vulnerabilities and reduced adherence. This scenario calls for measures such as strengthening epidemiological surveillance, addressing vaccine hesitancy and improving primary care. Regionalized analysis identifies priority territories and reinforces the need for coordinated interventions to restore herd immunity and avoid setbacks in public health.

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