RESUMEN
Background: Covishield (ChAdOx) and Covaxin (BBV-152) are the mainstream vaccines against severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) used in India and a few other countries. Objective: To assess the clinical outcomes of patients hospitalized with coronavirus disease 2019 (COVID-19) who had been vaccinated with either Covishield or Covaxin. Methods: This prospective, single-centre, observational cohort study of 1160 patients hospitalized with COVID-19 was conducted between April and June 2021. Severity of disease at admission and during hospitalization, requirement for intensive care unit (ICU) admission and ventilatory support, inflammatory markers (C-reactive protein, ferritin, lactate dehydrogenase, D-dimer), neutralizing antibody levels and mortality were assessed in vaccinated and unvaccinated patients. Results: More than 90% of patients in this study harboured the Delta variant (Pango lineage B.1.617.2) of SARS-CoV-2. Severity of disease at admission and during hospitalization (3.44% vs 7.51%; P=0.0032) and requirement for ICU admission and ventilatory support (2.83% vs 5.86%; P=0.0154) were significantly lower in vaccinated patients compared with unvaccinated patients. Vaccinated patients also had significantly (P<0.0001) higher antibody levels and lower inflammatory marker levels compared with unvaccinated patients. A subset of vaccinated, deceased patients mounted minimal antibody response ['non-responders': 4.53 (standard deviation 1.40) AU/mL]. Conclusion: These results demonstrate the effectiveness of Covishield and Covaxin against severe disease in patients hospitalized with COVID-19 with breakthrough infections caused by the Delta variant. Strategies targeting non-responders are desirable to minimize morbidity and mortality.