Estimated COVID-19 Severe Cases and Deaths Averted in the First Year Of the Vaccination Campaign in Brazil: A Retrospective Observational Study

Background: A nationwide severe respiratory syndrome coronavirus 2 (SARS-CoV-2) vaccination campaign was initiated in Brazil in January 2021 with CoronaVac (Sinovac Biotech) and ChAdOx1 nCoV-19 (AstraZeneca) followed by BNT162b2 mRNA (Pfizer–BioNTech) and Ad26.COV2.S (Johnson & Johnson–Janssen) vaccines. Here we provide estimates of the number of severe cases and deaths due to coronavirus disease (COVID-19) averted during the first year of the mass vaccination campaign in Brazil.Methods: Data on COVID-19 vaccination and COVID-19-related illness and death were obtained from the Brazilian Ministry of Health and used to estimate the direct effects of the vaccination campaign on the number of severe cases and deaths due to COVID-19 occurring between January 17, 2021 and January 31, 2022. To this end, we compared the daily age-specific rates between the unvaccinated population and the 'at least partly vaccinated' population (received at least one dose), as well as other two vaccination subgroups, 'fully vaccinated' (completed the one- or two-dose vaccine schedule), and 'boosted-vaccinated' (fully vaccinated and recipients of booster dose) populations.Findings: We estimated that 69% (n=875,846; 95% confidence interval 843,383–915,709) of total expected cases of severe COVID-19 and 77% (n=303,129; 95% confidence interval 284,019–321,681) of total expected deaths due to COVID-19 were averted in the first year of the national vaccination campaign. The averted burden was heterogeneous between age groups and higher in the more populous states. However, outcome rate differences between vaccinated and unvaccinated groups were higher in the less populated states.Interpretation: The first year of the COVID-19 vaccination program in Brazil saved the lives of a large number of adults. The results highlight the need for future vaccination campaigns, including those required in the current pandemic, to rapidly achieve high uptake, particularly among the elderly and residents of the least populous regions.Funding Information: This study was Funded by the Ministry of Health Brazil. CJS, GLW and CVBdS acknowledge suppport from Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) and Fundação de Amparo a Pesquisa do Estado do Rio de Janeiro (FAPERJ). DAMV is grateful for support from CNPQ/Brazil (Ref. 441057/2020-9, 309569/2019-2).Declaration of Interests: DAMV and TGN are affiliated with Fundação Oswaldo Cruz, which manufactures the ChAdOx nCoV-19 vaccine in Brazil through a full technology transfer agreement with AstraZeneca. All other authors declare no competing interests.Ethics Approval Statement: The study was conducted in accordance with fundamental ethical principles of the Declaration of Helsinki and the Brazilian National Health Council on research involving human beings. The study protocol was approved by the Research Ethics Committee of the Evandro Chagas National Institute of Infectious Diseases- Fiocruz (CAAE: 51567721.9.0000.5262).