Effectiveness of Different Vaccine Platforms in Reducing Mortality and Length of ICU Stay in Severe and Critical Cases of COVID-19 in the Omicron Variant Era: A National Cohort Study in Iran.

Abstract

Various SARS-CoV-2 vaccines with different platforms have been administered worldwide; however, their effectiveness in critical cases of COVID-19 has remained a concern. In this national cohort study, 24,016 ICU COVID-19 admissions were included from January to April 2022. The mortality and length of ICU-stay were compared between the vaccinated and unvaccinated patients. 9,428(39.25%) patients were unvaccinated, and 14,588(60.75%) patients had received at least one dose of the vaccine. Compared to the unvaccinated, the first, second, and third doses of vaccine resulted in 8%, 20%, and 33% lower risk of ICU mortality in the adjusted model, with RR 0.92, 95%CI(0.84 to 1.001), RR 0.80, 95%CI(0.77 to 0.83), and RR 0.67, 95%CI(0.64 to 0.71), respectively. The mean survival time was significantly shorter in the unvaccinated versus the fully vaccinated patients(HR 0.84, 95%CI(0.80 to 0.88); p<0.001). All vaccine platforms successfully decreased the hazard of ICU death compared to the unvaccinated group. The duration of ICU-stay was significantly shorter in the fully vaccinated than in unvaccinated group(MD -0.62, 95%CI(-0.82 to -0.42);p<0.001). Since COVID-19 vaccination in all doses and platforms has been able to reduce the risk of mortality and length of ICU-stay, universal vaccination is recommended based on vaccine availability. This article is protected by copyright. All rights reserved.