Peer-reviewed article

Classification of the risk of transmission of vaccine-preventable diseases among children under 2 years of age in the municipality of São Paulo, Brazil.

Mariana de Souza Araújo, José Elisomar Silva de Santana, Melissa Palmieri, Luciana Ursini Nunes, Thaís Moreira Oliveira et al. · 7 Aug 2026

Abstract

OBJECTIVE: To analyze the classification of the risk of transmission of vaccine-preventable diseases among children under 2 years of age in a large Brazilian municipality in 2022 and 2023. METHOD: Ecological epidemiological study using secondary data on vaccination coverage (VC) for nine immunobiologicals recommended in the vaccination schedule for children under 2 years of age. Immunobiological dose data were obtained from the National Immunization Program Information System (Sistema de Informações do Programa Nacional de Imunizações - SI-PNI), while data were collected from the Ministry of Health website and filtered by place of residence. Data were analyzed using the R software package. RESULTS: In 2022, 100% of the Health Surveillance Units (Unidades de Vigilância em Saúde - UVIS) showed low VC for the second dose of the measles-mumps-rubella (MMR) vaccine. In the same year, 61% and 54% of the UVIS achieved adequate VC for the hepatitis A and human rotavirus vaccines, respectively. In 2023, improvements in VC were observed for most vaccines, except for the meningococcal C and varicella vaccines, which showed a reduction in the number of UVIS achieving adequate VC. Regarding the classification of the risk of reintroduction of vaccine-preventable diseases, the proportion classified as "low and very low" increased from 0% in 2022 to 10.7% in 2023. CONCLUSION: VC improved in 2023 for most vaccines analyzed across the UVIS. However, variations in VC were observed according to vaccine type and year. These findings reinforce the need to maintain regional actions aimed at achieving vaccination targets, given the indications of a recovery in VC.