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.