Asynchronous influenza vaccination and adverse maternal-child health outcomes in the Brazilian semiarid, 2013 to 2018: the INFLUEN-SA Study

Abstract

Recent models indicate seasonal influenza transmission in Brazil begins each year in the semiarid state of Ceará−before vaccine campaigns begin. To assess the extent and maternal−child health consequences of this misalignment, we examined the burden of severe acute respiratory infections (SARI) and influenza from 2013-2018. Of 3,297 SARI cases, 145 (4%) occurred in pregnancy. Vaccine coverage was >80%; however, campaigns often occurred during or after peak influenza activity. Mean birth weights and gestational age nadired 30-40 weeks following peak influenza and SARI activity. We identified 61 babies of mothers with gestational SARI; they weighed 10% less at birth (P = 0.019) and were more often premature (OR: 2.944 ; 95% CI: 1.100 − 7.879) relative to controls (n=122). Mistiming of influenza vaccination adversely impacts pregnancy and birth outcomes in Ceará, with critical implications for the first 1000 days of life and influenza transmission dynamics nationally.