[Risk factors associated with maternal and child pertussis vaccination coverage in MexicoFatores de risco associados à vacinação materno-infantil contra a pertússis no México].

Objective: Identify the factors associated with lack of maternal and child vaccination during the 2024-2025 pertussis outbreak in Mexico. Methods: Retrospective multicenter study in 20 hospitals across 10 states. Maternal Tdap vaccination (tetanus, diphtheria, and acellular pertussis vaccine) and compliance with the childhood vaccination schedule at 2, 4, 6, and 18 months were recorded. Both Results: Tdap coverage in pregnancy was 35.7%. Maternal age was associated with a higher likelihood of vaccination (aOR 1.62 for every 5 years; 95% CI 1.07-2.47), while mothers ≤21 years of age had a lower likelihood (aOR 0.22; CI 95% 0.05-0.91). Education ≥ secondary increased coverage (aOR 12.51; CI 95% 1.48-106.03). In 99 evaluated children, 56.6% had an incomplete vaccination schedule, and maternal age ≥31 years was related to lower adherence (aOR 0.38; CI 95% 0.15-0.95). Conclusions: In this multicenter cohort from the 2024-2025 outbreak, low Tdap coverage in pregnancy and a high proportion of incomplete childhood vaccination were observed. Maternal vaccination was associated with older age and education, while young mothers had lower coverage. In children, adherence was lower with mothers ≥31 years. These findings underscore the need to strengthen prenatal vaccination strategies as a public health priority. It is also essential to consolidate adherence to the hexavalent childhood schedule and its boosters to reduce morbidity and mortality from pertussis in infants and prevent future outbreaks.