Effectiveness of Sinovac vaccine against SARS-CoV-2 (CoronaVac) in reducing in-hospital mortality in individuals with COVID-19 and schizophrenia: a retrospective cohort study

COVID-19 causes a huge burden on global health and is associated with mental health issues. Schizophrenia patients have impaired immune system, which leads to weaker resistance to virus. The effectiveness of CoronaVac in reducing in-hospital mortality in individuals with COVID-19 and schizophrenia is not well understood. The aim of this study was to determine the effects of Sinovac vaccine on patients with COVID-19 and schizophrenia, to guide clinicians and policies. This retrospective cohort study used patients’ data selected from the database Sistema de Informação da Vigilância Epidemiológica da Gripe (SIVEP-Gripe). Demographic and clinical conditions data were collected as covariate data. To compare intergroup descriptive statistics, Student t-test, Mann-Whitney test, and Fisher’s exact test were respectively used. Multivariable logistic regression was done for the primary outcome of in-hospital all-cause mortality, and adjusted odds ratio (aOR) was calculated. Hosmer–Lemeshow test, Receiver Operating Characteristic analysis, multivariable collinearity analysis, Akaike information criterion, and c-statistics were used to evaluate models. We report findings for eligible 1,983 patients, from SIVEP-Gripe, received Sinovac vaccines or no vaccines at all. Sinovac vaccination lowered in-hospital mortality by 52.0% in these patients (aOR = 0.480, 95%CI 0.349–0.660, p < 0.001). Moreover, each year of age increased mortality risk (aOR = 1.029, 95% CI 1.022–1.036). Patients in Northeast and North Brazil faced higher mortality (aOR = 1.744 and 2.811, respectively) compared to the Southeast. Immunocompromised status (aOR = 3.512, 95%CI 1.516–8.134, p = 0.003) and neurologic disease (aOR = 1.659, 95%CI 1.291–2.133, p < 0.001) independently elevated mortality risk. Sinovac vaccine can significantly reduce the in-hospital mortality in individuals with SARS-CoV-2 infection and schizophrenia, compared to those not-vaccinated.