Vaccination provides protection from respiratory deterioration and death among hospitalized COVID-19 patients: Differences between vector and mRNA vaccines

Outcomes of 109 hospitalized COVID-19 patients who received at least one vaccine dose 14 or more days prior the disease onset were retrospectively compared to control cohort of 109 age, sex, and Charlson comorbidity index-matched patients chosen among 2990 total hospitalized patients in our tertiary-level institution in a period from January to June 2021. Among 109 vaccinated patients, 84 patients were partially and 25 fully vaccinated. Vaccinated patients experienced significantly lower 30 days mortality (30% vs. 49%; hazard ratio [HR]: 0.56 [0.37-0.85]; p = 0.008), less frequently required high flow oxygen therapy (17% vs. 34%; HR: 0.45 [0.26-0.76]; p = 0.005), and mechanical ventilation (8% vs. 18%; HR: 0.41 [0.20-0.88]; p = 0.027) in comparison to the matched cohort of unvaccinated patients. More favorable survival was observed in patients receiving vector in comparison to messenger RNA (mRNA) vaccine types in unadjusted analysis (30 days mortality 18% vs. 40%; HR: 0.45 [0.25-0.79]; p = 0.034). In the multivariable Cox regression analysis model both mRNA (HR: 0.59 [0.36-0.98]; p = 0.041) and vector vaccine types (HR: 0.30 [0.15-0.60]; p < 0.001) were associated with improved survival in comparison to unvaccinated patients, independently of age (HR: 1.03 [1.01-1.06]; p = 0.011), male sex (HR: 1.78 [1.14-2.76]; p = 0.010), severity of illness (HR: 2.06 [1.36-3.10]; p < 0.001) and functional status on admission (HR: 1.42 [1.07-1.85]; p = 0.013).