COVID-19 vaccination is associated with lower mortality and intensive care unit admission among hospitalized patients with COVID-19: A retrospective cohort study

Background: The development of vaccines has played a significant role in managing the pandemic of COVID-19. The objective of this study was to investigate the impact of COVID-19 vaccination on mortality and intensive care unit (ICU) admissions. Methods: This retrospective, single-center cohort study included hospitalized COVID-19 patients with confirmed vaccination status from July 2021 to February 2022. Outcomes such as mortality and ICU admission were evaluated using clinical data. We used logistic regression and advanced statistical methods, including LASSO regression, to analyze differences in hospitalized COVID-19 patients based on vaccination status. Results: The study encompassed 167 patients (69% male, mean age 58 years, 95% CI [55; 60], 42% fully vaccinated) for data analysis. Vaccinated hospitalized COVID-19 patients exhibited a significantly reduced relative risk for mortality (RR: 0.46, 95% CI [0.13; 0.99]) and ICU admissions (RR: 0.59, 95% CI [0.28; 0.89]). The number needed to treat to prevent one ICU admission was four. The vaccination's protective effect was particularly pronounced in preventing ICU admissions among middle-aged patients (< 60 years) (RR: 0.64, 95% CI [0.32; 0.99]). Discussion: We found that hospitalized COVID-19 patients who have been vaccinated at least twice, exhibit a diminished risk with respect to mortality and ICU admission. The protective influence of vaccination appears to be particularly strong in younger patients. This could have implications for the vaccination strategy in a future pandemic. Conclusions: COVID-19 vaccination may mitigate the risk of mortality and ICU admission in hospitalized COVID-19 patients, particularly among middle-aged patients under 60 years old.