The early evolution of COVID-19 incidence and mortality among people aged under 80 years or 80 years and above after COVID-19 vaccine implementation in the state of Bahia, Brazil.

This study evaluates the early effects of COVID-19 vaccine implementation in the number of cases and deaths due to COVID-19 among those aged < 80 years or ≥ 80 years in the state of Bahia, Brazil. For that, we used data from the Bahia state Secretary of Health platform of cases and deaths due to COVID-19 in all age groups, between March 2020 and May 2021, when 82% of COVID-19 vaccines were CoronaVac. Overall, there were 1,012,200 cases and 21,241 deaths due to COVID-19, of which, respectively, 2.3% and 25.3% occurred in patients aged ≥ 80 years. The median proportion of deaths in those ≥ 80 years decreased from 29.8% (27.8%-30.4%) in the pre- to 18.8% (15.6%-18.8%) in the post-vaccine periods (p = 0.04). Significant reduction in the median proportion of deaths from COVID-19 among those aged ≥ 80 years after COVID-19 vaccine implementation was found, which suggests CoronaVac effectiveness against death from COVID-19 in the elderly.