FATORES DE RISCO PARA ÓBITO PELA COVID-19 E EFETIVIDADE DAS VACINAS CORONAVAC E CHADOX1 FRENTE A VARIANTE GAMA NO BRASIL

• Ano de defesa: 2022
• Autor(a) principal: PATRICIA VIEIRA DA SILVA
• Orientador(a): Julio Henrique Rosa Croda
• Tipo de documento: Tese
• Tipo de acesso: Acesso aberto
• Idioma: por
• Instituição de defesa: Fundação Universidade Federal de Mato Grosso do Sul
• País: Brasil
• Palavras-chave em Português: COVID-19, Fatores de Risco, Variante Gama, Vacina
• Link de acesso: https://repositorio.ufms.br/handle/123456789/4967

In December 2019, an outbreak of pneumonia of unknown origin was reported in China. The etiologic agent was identified as severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), and the disease named as novel coronavirus disease 2019 (COVID-19). The virus has spread all over the world and in Brazil more than 30 million cases and 663 thousand deaths have been recorded. Highly disproportionate numbers of deaths have been identified among some groups, prompting the need to elucidated which risk factors are associated with severe COVID-19 outcomes. Vaccines against SARS-CoV-2 have been developed, proven effective and deployed in mass vaccination campaigns. Among them, the first two vaccines distributed in Brazil, CoronaVac and ChAdOx1, stand out. The emergence of variants of concern (VOCs), such as the Gamma variant, created the need for continuous monitoring of the effectiveness of vaccines, since mutations observed in these variants can provide escape immunity and neutralization of immunizers. Given the above, this study aims to describe the risk factors for death from COVID-19 and estimate the effectiveness of the first two vaccines against the Gamma variant in Brazil. Different methodologies were used in this study. To identify risk factors for death, a survival analysis was performed with all hospitalized patients with COVID-19 confirmed by RT-PCR in the state of São Paulo registered in the Influenza Epidemiological Surveillance System (SIVEP-GRIPE) in the period from February 26, 2020 to October 10, 2020. For the effectiveness study, a matched, test-negative case-control study was carried out, comparing the cases of COVID-19 confirmed by RT-PCR, hospitalization and death, in the elderly during the epidemic with a high prevalence of the Gamma variant in the state of São Paulo, with administered doses of CoronaVac and ChAdOx1. We observed that men, the elderly, and people with comorbidities had a higher risk of death from COVID-19. The adjusted effectiveness of CoronaVac against symptomatic COVID-19 was 24.7% at 0-13 days and 46.8% at ≥14 days after the second dose. The adjusted effectiveness against hospitalizations was 55.5% and against deaths it was 61.2% ≥14 days after the second dose. The effectiveness of CoronaVac decreased with increasing age. From 28 days after the first dose, the effectiveness of ChAdOx1 was 33.4% against symptomatic COVID-19, 55.1% against hospitalization, and 61.8% against death. As of 14 days after the second dose, the effectiveness of the two-dose regimen was 77.9% against COVID-19, 87.6% against hospitalization, and 93.6% against death. According to the results obtained, people who have risk factors for worsening the infection should be prioritized in vaccination, in order to reduce mortality from COVID-19. Additionally, completion of the two-dose vaccine schedule with CoronaVac and ChAdOx1 provides protection against both mild and severe COVID- 19 outcomes in older adults during widespread Gamma variant circulation.