Estimating the early impact of immunization against COVID-19 on deaths among elderly people in Brazil: analyses of secondary data on vaccine coverage and mortality.

Victora, C. G.; Castro, M. C.; Gurzenda, S.; Barros, A. J.

ABSTRACT Background Immunization against COVID-19 in Brazil started in January 2021, with health workers and the elderly as the priority groups. We assessed whether there was an impact of immunizations on the mortality of individuals aged 80+ years. Methods By April 22, 2021, 147,454 COVID-19 deaths had been reported to the Brazilian Mortality Information System. Denominators for mortality rates were calculated by correcting population estimates for all-cause deaths reported in 2020. Proportionate mortality at ages 80+ and 90+ years relative to deaths at all ages were calculated, and mortality rate ratios compared these two age groups with individuals aged 0-79 years. Vaccine coverage data were obtained from the Ministry of Health vaccination monitoring website. All results were tabulated by two-week periods from epidemiological weeks 1-14, 2021. Findings As the P.1 variant spread throughout Brazil, the total number of deaths increased over time starting in epidemiological week 9 of 2021. The proportion of all deaths occurring at ages 80+ years was over 25% in weeks 1-6 and declined rapidly to 13.1% in weeks 13-14. Mortality rates were over 13 times higher in the 80+ years age group compared to that of 0-79 year olds up to week 6, and declined to 6.9 times in weeks 13-14. Coronavac accounted for 77.3% and AstraZeneca for 15.9% of all doses administered. Vaccination coverage (first dose) increased rapidly among individuals aged 80+ years, reaching 49.1% in weeks 5-6 and over 90% after week 9. Interpretation Rapid scaling up of vaccination coverage among elderly Brazilians was associated with an important decline in relative mortality compared to younger individuals, in a setting where the P.1 variant predominates. Had mortality rates among the elderly remained proportionate to what was observed up to week 6, an estimated additional 13,824 deaths would have been expected up to week 14.