Impact of SARS-CoV-2 variants on modulating COVID-19 case and death curves in Brazil

Even though it shares a high genetic similarity to its predecessor, SARS-CoV-2 is more easily transmitted, mainly through aerosols, contact with infected individuals, and contaminated surfaces. Coronaviruses show a high rate of mutations per infectious unit produced, resulting in the emergence of different variants and lineages, potentially having a much greater severity than the original strain. The present study observed an increase in the average number of cases between 2020 and 2021, followed by a reduction in cases in 2022 compared to 2021, which may have been caused by the increase in the vaccination rate between 2021 and 2022. There was a strong anti-vaccine movement, affecting the population's vaccination schedule and interfering in the association between cases, deaths, and vaccine doses, stimulating the selection of strains capable of reducing the effectiveness of the vaccines distributed. There are limitations regarding underreporting, however, it can be concluded that the vaccination schedule stipulated by the Ministry of Health of Brazil effectively controlled the pandemic in Brazil, while the variants are directly related to the modulation of the disease curves.