ABSTRACT
Objective
To analyze the clinical and sociodemographic characteristics and survival of individuals with severe acute respiratory syndrome due to COVID-19 according to the COVID-19 vaccination schedule, Brazil, 2021-2022.
Methods
This was a cohort study based on data from the Influenza Epidemiological Surveillance Information System; the Kaplan-Meier and Survival Tree methods were used to analyze survival.
Results
Among the 559,866 hospitalized cases, a higher proportion of vaccinated individuals was found among female (15.0%), elderly people aged ≥ 80 (34.5%), people from the Southeast region (15.7%), those who did not undergo respiratory support (21.2%) and those who did progress to death (15.2%); the survival curve showed that risk of death for unvaccinated individuals was higher in all age groups (p-value < 0.001); elderly people aged ≥ 80, who did not undergo mechanical ventilation and who had a booster dose had lower risk when compared to their peers who had two doses or were unvaccinated (hazard ratio = 0.64; 95%CI 0.62;0.67).
Conclusion
Lowest risk of death was found in vaccinated individuals, especially those who had two doses or a booster dose as well.
Keywords
COVID-19; SARS-CoV-2; Survival Analysis; COVID-19 Vaccine; Cohort Studies
Study contributions
Main results
Prevalence was found to be high among unvaccinated individuals. Risk of death was lower among those vaccinated with a booster dose, compared to those not vaccinated, in all age groups analyzed.
Implications for services
The number of hospitalizations of unvaccinated individuals with severe acute respiratory syndrome was high, which increases the demand for health services to care for these individuals.
Perspectives
It is necessary to promote widespread vaccination of the entire population of Brazil, in addition to the regular provision of booster doses for the different population groups.
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1,14,18) Ventilação mecânica: respiratory support (not performed; noninvasive; invasive); 2,7,12,23,27) Faixa etária: age group (age on last birthday: 20-39; 40-59; 60-79; 80 or over); 3,13,20,24) Esquema vacinal: vaccination schedule [not immunized (not vaccinated or with an incomplete vaccination schedule); two doses; and booster dose]; 5) UTI: hospitalized in an intensive care unit [ICU, (yes; no)]; 6) Fator de risco: presence of risk factors/comorbidities (none; one or more). Notes: The squares represent the terminal nodes; each one contains the number of cases in that node (n) and the survival curve, estimated by the Kaplan-Meier method. The circles represent the internal nodes (intermediate or decision-making), contemplating the decisionmaking explanatory variable that will lead to a new split of the tree. Vaccination schedule: “no” for not immunized; “two” for two doses; and “boost” for booster dose.