A Pharmacovigilance Study of Covishield in a Tertiary Care Teaching Hospital in Tamil Nadu

Objective: To study the adverse events following immunization (AEFI) with Covishield, a coronavirus disease– 2019 (COVID-19) vaccine. Materials and Methods: A prospective observational study was conducted among 422 Covishield vaccinees based on the inclusion and exclusion criteria after the institutional ethics committee approval. They were followed up at the end of 1 and 2 weeks following the first dose of Covishield vaccine, and the details of adverse events were collected. AEFIs were classified using system organ classification, World Health Organization-Uppsala Monitoring Center (WHO-UMC) causality assessment, AEFI causality assessment, and Modified Hartwig Severity Scale. Various classifications of AEFI were analyzed using descriptive statistics. ANOVA and independent t-test were used for age group and gender comparison of the duration and number of AEFI, respectively. Results: Around 625 AEFIs were reported by 422 vaccinees. Majority of the vaccinees (62.8%) developed adverse events on the day of vaccination. The mean duration of AEFI was 2.52 ± 0.871 days. On WHO-UMC causality assessment, 98.08% were found to be probable, 1.12% possible, and 0.8% unclassifiable. AEFI causality assessment revealed 98.88% vaccine product-related reactions and 1.12% anxiety-related reactions. Regarding the severity, 83.52% of AEFIs were mild and 16.32% were moderate. On comparison of mean duration of AEFI (P = 0.298) and mean number of AEFI (P = 0.569) between different age groups, no statistical significance was observed. Conclusion: The majority of AEFIs reported in this study were mild to moderate in severity for a short duration. The protection offered against the deadly disease and its complication potentially outweighs the mild AEFIs or inconvenience caused by them. Hence, covid-19 vaccination is an important tool to break the pandemic chain.