Effectiveness of BBV152 vaccine against SARS-CoV-2 infections, hospitalizations and deaths among healthcare workers in the setting of high delta variant transmission in New Delhi, India

Background Transmission of the delta variant resulted in a surge of SARS-CoV-2 cases in New Delhi, India, during the early half of the year 2021. Healthcare workers (HCWs) received vaccines on priority for the prevention of infection. We estimated the effectiveness of the BBV152 vaccine among HCWs against SARS-CoV-2 infection, hospitalization, or death. Methods This retrospective cohort study was done at a multi-speciality tertiary care public-funded hospital in New Delhi, India. 12 237 HCWs participated in the study. The intervention was the BBV152 whole virion inactivated vaccine (Covaxin, Bharat Biotech Limited, Hyderabad, administered two doses four weeks apart). The outcome measures were vaccine effectiveness against any SARS-CoV-2 infection, symptomatic infection, or hospitalization or death. Results The mean (SD) age of HCWs was 36 (11) years, 66% were men, and 16% had comorbid conditions. After adjusting for potential covariates-age, sex, health worker type category, body mass index, and comorbid conditions, the vaccine effectiveness (95% confidence interval) in fully vaccinated HCWs and >14 days after receipt of the second dose was 44% (37 to 51, p<0.001) against sympto-matic infection, hospitalization or death due to SARS-CoV-2, and 61% (37 to 76, p<0.001) against hospitalization or death, respectively. The partial dose was not effective. Conclusion The BBV152 vaccine, with complete two doses, offered a modest response to SARS-CoV-2 infection in real-life situations against a backdrop of high delta variant community transmission.