Vaccine protection against COVID-19-related mortality in patients with schizophrenia: a retrospective cohort study

This study analyzed the role of vaccination in preventing COVID-19-related mortality in patients with schizophrenia.

This retrospective cohort study analyzed data from the Influenza Epidemiological Surveillance Information System (Sistema de Informação da Vigilância Epidemiológica da Gripe [SIVEP-Gripe]) database, focusing on patients aged = 18 years with laboratory-confirmed COVID-19 between February 2020 and February 2023. The primary exposure was schizophrenia. The primary outcome of interest was the role of vaccines in preventing COVID-19-associated mortality. Statistical analysis included multiple binary logistic regressions to determine the impact of schizophrenia on mortality and to compare vaccine protection between cohorts.

The cohort included 2,131,089 patients, 3,516 (0.2%) of whom had schizophrenia. After adjusting for potential confounders, patients with schizophrenia presented a significantly higher risk of severe disease (OR = 1.59, 95%CI 1.39-1.81) and mortality (OR = 1.65, 95%CI 1.45-1.87). After the booster dose, protection against mortality was estimated at 67.7% (95%CI 66.5-68.7) in the non-schizophrenia cohort and 62.4% (95%CI 44.1-74.6) in the schizophrenia cohort. Mortality rate differences of approximately 20% and 10% were observed between boosted and non-vaccinated individuals among the schizophrenia and non-schizophrenia cohorts, respectively. Consequently, five patients (95%CI 4-8) with schizophrenia and 10 patients (95%CI 9-11) in the general population would need to receive a booster dose to prevent one fatality.

Our results suggest that vaccination provided similar protection against COVID-19-related mortality in individuals with and without schizophrenia. However, the magnitude of the intervention effect was double for individuals with schizophrenia due to their higher baseline risk.