Impact of Individual and Contextual Factors on Measles, Mumps, and Rubella Vaccination in Brazil: A Multilevel Analysis

Vaccination is a crucial public health intervention, and Brazils National Immunization Program (PNI) has historically achieved high coverage rates. However, since 2014, and especially during the COVID-19 pandemic, MMR (measles, mumps, and rubella) vaccine coverage has declined significantly. In this context, understanding how individual and contextual factors contribute to incomplete vaccination is vital to reversing this trend and preventing disease resurgence. The objective of this study was to analyze the influence of individual, household, and contextual factors on incomplete MMR vaccination in Brazilian children, using a multilevel analytical approach. This study analyzed secondary data from the 2020 National Immunization Coverage Survey, which assessed MMR vaccination among children born in 2017 and 2018. The survey included 26 state capitals, the Federal District, and 12 mid-sized municipalities. Multilevel logistic regression models were used to identify factors associated with the absence of a valid second MMR dose. The absence of a second MMR dose was significantly associated with higher birth order, maternal employment, and not having a partner. Maternal education showed a protective effect, especially among mothers with higher education levels. Participation in the Bolsa Familia program reduced the likelihood of incomplete vaccination. Unexpectedly, children in lower socioeconomic strata (C and D) had lower odds of incomplete vaccination than those in wealthier strata, suggesting effective targeting of public policies. Most of the variance occurred at the Primary Sampling Unit level, highlighting the importance of local health infrastructure. Incomplete MMR vaccination in Brazil is influenced by both individual and contextual factors. Equity-focused strategies that address maternal workload, family structure, and local service delivery are essential to improving coverage and preventing the resurgence of vaccine-preventable diseases.