To evaluate the impact of previous vaccination with Gam-COVID-Vac on all-cause mortality in hospitalized adult patients with breakthrough COVID-19.
Material and methods
In a prospective study, we enrolled consecutive unvaccinated and vaccinated patients with COVID-19 who were hospitalized to one center. Patients were regarded as vaccinated if they were administered at least one component of Gam-COVID-Vac (Sputnik V) 21 days or more prior to admission. The odds ratios (OR) and 95% confidence intervals (CI) for the primary end point of death from all causes were calculated using multivariate regression analysis. IgG antibodies to the receptor binding domain (RBD) of the S1 subunit of the spike protein of SARS-CoV-2 were measured withing 72 hours after hospitalization with chemiluminescent microparticle immunoassay (ARCHITECT, Abbott).
We studied 158 vaccinated and 473 unvaccinated patients with COVID-19 (median age 67 and 71 years, 50.6% and 41.0% males, respectively). In multivariate regression analysis adjusted for age and gender, previous vaccination with Gam-COVID-19 was associated with a 62% reduction in the risk of death from all causes (OR 0.38, 95% CI 0.19-0.77). The effect of vaccination on mortality in breakthrough COVID19 patients was similar in various subgroups (males and females, age ≥75 or 75 years, cardiovascular comorbidity) and depended on the titer of the RBD antibodies. More vaccinated patients did not require supplemental oxygen or respiratory support compared to unvaccinated patients (65.8% vs 43.3%; p<0.001).
Vaccination with Gam-COVID-Vac reduces the risk of death from all causes in hospitalized patients with breakthrough COVID-19.
Breakthrough COVID-19, vaccination, GamCOVID-Vac, Sputnik V, outcomes.