Effectiveness of BNT162B2 and CoronaVac vaccines in reducing COVID-19 severity among children aged 3-4 years in Brazil.
Two-dose CoronaVac/BNT162b2 cut COVID-19 hospitalization by half in children aged 3-4
Effectiveness of BNT162B2 and CoronaVac vaccines in reducing COVID-19 severity among children aged 3-4 years in Brazil.
National population-based databases from large countries can provide real-world estimates of COVID-19 vaccine effectiveness.
This analysis examined the effectiveness of BNT162b2 and CoronaVac against severe COVID-19-related outcomes in children aged 3 to 4 years during the Omicron phase of the pandemic in Brazil.
This nationwide population-based cohort study assessed incidence rate ratios for hospitalization due to COVID-19-associated severe acute respiratory syndrome, invasive ventilatory support, and death among children aged 3 to 4 years, according to vaccination status (unvaccinated, 1 dose, or 2 doses), during 2022-2023.
risk of hospitalization was about half after full vaccination
Among children aged 3 to 4 years completion of the primary series increased to 15% for CoronaVac and 2% for BNT162b2 during the study period, corresponding to 797,956 and 79,650 individuals receiving the second dose, respectively.
A total of 963 children were hospitalized with COVID-19-associated severe acute respiratory syndrome.
Effectiveness against invasive mechanical ventilation was 77.6% and 79.1%, respectively; no deaths occurred among fully vaccinated children.
Direct comparisons between vaccines were not feasible because of the lower proportion of BNT162b2 recipients.
COVID-19 vaccination, predominantly based on the CoronaVac vaccine, was associated with a significant reduction in severe outcomes among children aged 3-4 years, providing robust evidence to support pediatric immunization strategies and public health efforts.