Adverse events following COVISHIELD (ChAdOx1nCoV-19) vaccination among health care workers in Sri Lanka; a multi-centre cross sectional survey

Abstract Introduction A community vaccination programme is the best approach to combat the COVID-19 pandemic. Post-vaccine surveillance is important to identify adverse events (AE) following COVID -19 vaccination in the population. Methods A multicentre cross-sectional survey was conducted in six provinces to estimate the prevalence of AE following the first dose of COVISHIELD (ChAdOx1nCoV-19) among all categories of health care workers (HCWs). A self-administered questionnaire was used to gather demographic data and AE. Results Of 5140 participants 67.8% were females. The mean (SD) age was 40.69 (+/-9.85) years. At least one comorbidity was reported in 15.4%. At least one AE was reported in 86.6% and 49.3% had local AE. Fever (67.2%), headaches (57.3%), body aches (54.4%), chills (51.2%), fatigue (37.5%) and arthralgia (36%) were the most reported systemic AE. The majority of AE lasted less than 24 hours. Pain and redness at the site were the most reported local AE. Mean duration of onset of fever and pain at injection site from the time of the vaccination was 6.65 and 9.67 hours respectively. When participants were divided into two groups by mean age (less or equal 40years and more than 40 years) and parameters were compared, most systemic (fever, nausea, fatigue, itching) and all local AE were significantly more prevalent in the [≤]40 age group. Two percent had reactions within the first 20 minutes. Anaphylaxis developed in 12 participants. Past history of anaphylaxis, drug or food allergy were reported in 0.6%, 2.8% and 6.7% respectively. However, previous history of allergy was not significantly related to immediate reactions or anaphylaxis following vaccination. Despite having minor AE, 71.1% attended routine work while 0.2% required hospitalisation. Conclusions While 86.6% reported minor AE, only a few serious AE were reported. Overall, the first dose of the vaccine was well-tolerated by HCWs.