Lessons Learned from the COVID-19 Pandemic: Interpreting Vaccination Strategies in a Nationwide Demographic Study

Objective: Brazil was strongly affected by the COVID-19 pandemic. Its continental dimension and socio-demographic characteristics pose challenges to distribution and accessibility, making vaccination programs challenging. The objectives of the study were to describe the clinical and demographic characteristics of the general population vaccinated against COVID-19 by October 2021 and analyze the strategies implemented during the vaccination program. Study design and setting: A retrospective nationwide study that analyzed data from the OpenDataSUS platform of the Informatics Department of the Brazilian Ministry of Health (DataSUS), which contains information from all individuals in Brazil who have received at least one dose of any vaccine against COVID-19 approved by the National Health Agency (ANVISA) from 17 January to 3 October 2021. Results: Until 3 October, a total of 146,254,578 persons (68.6 per 100 inhabitants) received at least one dose of a vaccine in Brazil. The north and northeast regions had the lowest vaccination rates compared with the remaining regions (North: 56.8, Northeast: 62.0, South: 74.4, and Southeast: 73.2 per 100 inhabitants). Elderly individuals had the highest vaccination rates, particularly those above 70 years old. Heterologous dosing regimens were administered to 1,063,079 individuals (0.7% of those receiving the first dose). Conclusions: The COVID-19 vaccination program reached more than two-thirds of the population in Brazil by 9 months after its start, but the vaccination coverage was heterogeneous, reflecting the country's geographic and socio-demographic characteristics. Establishing priority groups for vaccination was a main characteristic of the vaccination strategy. In addition, technology transfer agreements have played an important role in increasing vaccine accessibility.