Impact of COVID-19 Vaccination and Vaccine Type on Morbidity and Mortality in Hospitalized Patients: A Retrospective Cohort Study in Egypt

Mostafa Bahaa^1*Ramy El Sabaa²Shrouq Sayed Abdelrazik³Rana A. Hussein³Marwa M. Gaballah³Reem S. Mahmoud³Nourhan M. Kamal³Mostafa Ahmed³Ahmed Essam⁴Seif El Hadidi⁵Heba Khaled⁶Heba Salama⁷Haidy M. Sami⁸Hayam Ali AlRasheed⁹Abdelrahman SH Refaee³Nehal Mohamed Eisa³

• ¹Faculty of Pharmacy, Horus University, Damietta, Egypt
• ²Menoufia University, Shebeen El-Kom, Egypt
• ³Clinical research department at Giza health affairs Directorate, MOHP, Giza, Egypt, Giza, Egypt
• ⁴October 6 University, 6th of October City, Egypt
• ⁵University of Hertfordshire School of Life and Medical Sciences, Hatfield, United Kingdom
• ⁶Cairo University, Giza, Egypt
• ⁷Giza Memorial Institute for Ophthalmic Research, Giza, 12585, Egypt, Giza, Egypt
• ⁸Delta State University of Science & Technology Ozoro, Ozoro, Nigeria
• ⁹Princess Nourah bint Abdulrahman University, Riyadh, Saudi Arabia

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.