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

Abstract

Introduction:The ChAdOx1 nCoV-19 (Covisheild) vaccine was well tolerated with low reactogenicity in the clinical trials. However, shortly after initiating mass vaccination programmes in many countries, safety concerns resulted in vaccine hesitancy among populations.Objectives: This prospective single-cohort study was conducted to assess adverse events following immunization (AEFI) and associated factors of the ChAdOx1 nCoV-19 vaccine among staff members of the University Hospital of General Sir John Kotelawala Defence University (UHKDU).Methods: A total of 688 staff members who received the first dose of the ChAdOx1 nCoV-19 vaccine from 30 th January to 5 th February 2021 were enrolled and followed up until the completion of vaccination. Of them, 635 responded after the second dose. 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 was significantly less after the second dose of vaccination (n=134, 21.1%, p<0.001). Fever was the commonest adverse event after the first dose (n=389, 56.5%), and