Impact of COVID-19 vaccination and vaccine type on morbidity and mortality in hospitalized patients: a retrospective cohort study in Egypt

Abstract

Background COVID-19 remains associated with significant morbidity and mortality, particularly among hospitalized patients. Vaccination has been shown to reduce disease severity; however, real-world data comparing outcomes between vaccinated and unvaccinated patients and among different vaccine types remain limited. Methods This study included 478 hospitalized patients with suspected or confirmed COVID-19. Demographic characteristics, vaccination status, comorbidities, disease severity, clinical outcomes, and mortality were assessed. Comparative analyses were performed between vaccinated and unvaccinated patients. Multivariable logistic regression was conducted to identify independent predictors of survival. A head-to-head comparison evaluated the impact of different vaccine types on hospitalization and outcomes. Results The mean age of patients was 60.63 ± 13.86 years, and 56.9% were female. Most patients were unvaccinated (74.9%). Overall mortality was 19.46%. Vaccinated patients demonstrated a significantly higher recovery rate (67.5% vs. 35.75%) and lower mortality (12.5% vs. 21.79%, p < 0.05) compared with unvaccinated patients. Disease severity was significantly lower among vaccinated patients, with a greater proportion requiring only nasal cannula or simple mask oxygen therapy ( p < 0.001). Multivariable logistic regression identified milder disease severity, absence of comorbidities, and Moderna vaccination as independent predictors of survival, while the need for CPAP or mechanical ventilation was strongly associated with reduced survival. Head-to-head comparison among different vaccine types showed no significant differences in hospital stay duration, outcomes, mortality rates, PCR results, or disease severity. Conclusion COVID-19 vaccination was associated with improved clinical outcomes, reduced disease severity, and lower mortality among hospitalized patients. Disease severity and comorbidity burden were the strongest predictors of survival. No significant differences were observed among vaccine types in clinical outcomes. These findings support the protective role of COVID-19 vaccination in reducing severe disease and mortality.