Guilherme Jorge Costa1, José Roberto da Silva Junior2, Caio Cesar Arruda da Silva2, Tiago Pessoa Ferreira de Lima3, Mariana Menezes Costa2, Marcos Henrique Oliveira Sousa2, Gabriela Carla dos Santos Costa1, José Iran Costa Júnior1, Mozart Júlio Tabosa Sales2
Objective: To determine the clinical profile of COVID-19 inpatients who were vaccinated prior to hospitalization and to compare the risk factors for death and the 28-day survival rate of between those inpatients vaccinated with one, two, or three doses and unvaccinated COVID-19 inpatients. Methods: This was a retrospective observational cohort study involving COVID-19 patients admitted to a referral hospital in the city of Recife, Brazil, between July of 2020 and June of 2022. Results: The sample comprised 1,921 inpatients, 996 of whom (50.8%) were vaccinated prior to hospitalization. After adjusting the mortality risk for vaccinated patients, those undergoing invasive mechanical ventilation (IMV) had the highest mortality risk (adjusted OR [aOR] = 7.4; 95% CI, 3.8-14.1; p < 0.001), followed by patients > 80 years of age (aOR = 7.3; 95% CI, 3.4-15.4; p < 0.001), and those needing vasopressors (aOR = 5.6; 95% CI, 2.9-10.9; p < 0.001). After adjusting the mortality risk for all patients, having received three vaccine doses (aOR = 0.06; 95% CI, 0.03-0.11; p < 0.001) was the most important protective factor against death. There were progressive benefits of vaccination, reducing the frequency of ICU admissions, use for IMV, and death (respectively, from 44.9%, 39.0% and 39.9% after the first dose to 16.7%, 6.2% and 4.4% after the third dose), as well as significant improvements in survival after each subsequent dose (p < 0.001). Conclusions: Vaccines were effective in reducing illness severity and death in this cohort of COVID-19 inpatients, and the administration of additional doses conferred them with accumulative vaccine protection.
Keywords: COVID-19; Risk factors; Hospital mortality; Vaccination.