A Real World Evaluation of the safety and immunogenicity of the Covishield vaccine, ChAdOx1 nCoV- 19 Corona Virus Vaccine (Recombinant) in Health Care Workers (HCW) in National Capital Region (NCR) of India: A preliminary report

BackgroundThe SARS-CoV-2 pandemic has severely impacted health systems, economic and social progress globally in 2020. The rollout of vaccines in several parts of the world is being hailed as a solution to the crisis. With newer and more virulent serotypes on the horizon and limited vaccine available, evaluation of safety and immunogenicity is critical for rationalization of vaccine use in public health. ObjectiveTo evaluate real world safety, and, immunogenicity of the Covishield vaccine, ChAdOx1 nCoV-19 Corona Virus Vaccine (Recombinant) in Health Care Workers (HCW) during the national vaccine roll out in the NCR, New Delhi. The safety is evaluated through Adverse Events and Serious Adverse Events reported though enhanced pharmacovigilance protocols, and, the immunogenicity by quantitative determination of anti-S1 and anti-S2 specific IgG antibodies to SARS-CoV-2 in serum samples collected before the receipt of the vaccine and 14 days after dose 1, using the fully automated LIAISON(R) SARS-CoV-2 S1/S2 IgG test using the chemiluminescence immunoassay (CLIA) ResultsIn the two weeks after immunization with the Covishield vaccine {ChAdOx1 nCoV-19 Corona Virus Vaccine (Recombinant)}, none of the 1638 evaluated participants reported any serious adverse events (ie require hospitalization or emergency room visit). Solicited adverse events reported via daily diary cards included pain (62.7%) and soreness (24.1%) at injection site as most common, whereas fever (48.4%), headache (43.4%), myalgia (38.4%), fatigue (33.4%), joint pain (27.0%) and nausea (16.0%) were most common solicited systemic adverse events on day 1. Majority of local and systemic adverse events were seen in first 2 days post vaccination and thereafter they resolved. Lesser reactogenicity was observed in subjects with age >50 years. No major difference was observed in adverse events when subjects were stratified based on history of COVID 19 disease or baseline seropositivity. In our study serostatus improved from 48.2% positive at baseline to 79.0% positive 2 weeks following first dose of vaccination. After first dose of vaccination overall higher percentage (98.2%) of seropositivity rates were observed in those with past history of COVID 19 disease ConclusionThe Covishield vaccine {ChAdOx1 nCoV-19 Corona Virus Vaccine (Recombinant)}, was safe and reported mild self limiting adverse events over 2-4 days and had an good early (within 2 weeks) seroresponse. This holds the promise of far reaching impact on vaccine availability for a larger population and thereby providing a widespread coverage.