Role of vaccination and anti-SARS-CoV-2 antibodies in the clinical outcome of hospitalized COVID-19 patients

Background Although vaccination has considerably reduced the risk of hospitalization and death from COVID19, the impact of vaccination and anti-SARS-CoV-2 antibody status on the outcome of patients who required hospitalization has been poorly investigated. Material and methods A prospective observational study in 232 patients hospitalized for COVID19 was carried out from October 2021 to January 2022 to evaluate the role on patient outcome of their vaccination and anti-SARS-CoV-2 antibody status and titer, comorbidities, analytical determinations, clinical presentation at admission, treatments and requirements for respiratory support. Cox regression and survival analyzes were performed. The SPSS and “R” programs were used. Results Patients with complete vaccination schedule had higher S-protein antibody titers (log10 3.73 [2.83–4.6] UI/ml vs 1.6 [2.99–2.61] UI/ml; p  < 0.001), lower probability of radiographic worsening (21.6% vs. 35.4%; p  = 0.005), less likely required high doses of dexamethasone (28.4% vs. 45.4%; p  = 0.012), high-flow oxygen (20.6% vs. 35.4%; p  = 0.02), ventilation (13.7% vs, 33.8%; p  = 0.001) and intensive care admissions (10.8% vs. 32.6%; p  < 0.001). Remdesivir (HR = 0.38; p  < 0.001) and complete vaccination schedule (HR = 0.34; p  = 0.008) were protective factors. No differences in antibody status were detected between groups (HR = 0.58; p  = 0.219). Conclusions SARS-CoV-2 vaccination was associated with higher S-protein antibody titers and lower probability of radiological progression, immunomodulators requirement and respiratory support or death. However, vaccination but not antibody titters protected from adverse events pointing a role of immune-protective mechanisms in addition to humoral response.