COVID-19 vaccine effectiveness against in-hospital mortality in immunocompromised older adults: a Brazilian hospital surveillance study, 2024.

OBJECTIVE

The study evaluated the association between COVID-19 vaccination and in-hospital mortality among immunocompromised older adults hospitalized for COVID-19 in Brazil during the 2024 epidemiologic year.

METHODS

This retrospective hospital-based surveillance study used data from the Brazilian SIVEP-Gripe database. All hospitalized cases of COVID-19-related severe acute respiratory syndrome in immunocompromised individuals aged ≥60 years reported during epidemiological weeks 1-52 of 2024 were included. Multivariable logistic regression was used to estimate odds ratio (OR) and 95% confidence interval (95%CI) for the association between COVID-19 vaccination (number of doses) and in-hospital mortality, adjusting for clinical and sociodemographic covariates.

RESULTS

Among 474 patients, in-hospital mortality was 36% (171/474). Only 56 (12%) were unvaccinated. Compared with unvaccinated individuals, adjusted ORs for mortality were 0.67 (95%CI 0.32-1.39) for 1-2 doses, 0.67 (95%CI 0.31-1.42) for 3 doses, 0.54 (95%CI 0.26-1.15) for 4 doses, and 0.56 (95%CI 0.26-1.17) for 5-6 doses. Mechanical ventilation (OR 12.55; 95%CI 6.39-26.33) and lower educational attainment (elementary education: OR 2.94; 95%CI 1.39-6.44) were independent predictors of death. COVID-19 vaccination was not significantly associated with reduced in-hospital mortality among immunocompromised older adults hospitalized for the disease in Brazil in 2024. However, all adjusted ORs were below unity, suggesting a trend toward protection with increasing doses.

CONCLUSIONS

The strong association of mortality with mechanical ventilation and social determinants highlights the need for timely boosters and comprehensive preventive strategies for this vulnerable population.