Adverse events following ChAdOx1 nCoV-19 (Covisheild) vaccine administered in two-dose regimen: A single centre experience from Sri Lanka

Introduction Phased distribution of the ChAdOx1nCoV-19 (Covisheild) vaccine was commenced in Sri Lanka in January 2021. Although the vaccine was well tolerated with a low reactogenicity profile in the clinical trials, there were safety concerns shortly after initiating vaccine rollouts in many countries. Objectives This prospective observational study aimed to profile the adverse events following immunization (AEFI) amongst recipients of the ChAdOx1nCoV-19 between 30th January to 5th February at the University Hospital, KDU. The associations of AEFI were also evaluated. Methods A cohort of 688 was followed up till the completion of vaccination. Data were collected using an interviewer-administered questionnaire and through telephone interviews. AEFI were classified according to WHO criteria. Results A total of 516(74.9%) participants experienced AEFI after the first dose, of which 377(73.0%) reported both systemic and local symptoms. By contrast, the incidence of AEFI were significantly lower after the second dose (n=134,21.1%, p