# Safety Surveillance of Covishield Vaccine-Associated Adverse Events During the COVID-19 Pandemic: A Retrospective Longitudinal Study

## TL;DR

This study analyzed adverse events following Covishield vaccine administration in North India, finding mostly mild to moderate effects with higher incidence after the first dose.

## Contribution

The study provides novel safety data on Covishield vaccine adverse events in a specific Indian population over an 18-month period.

## Key findings

- Most adverse events were mild, systemic, and occurred within 12 hours of vaccination.
- First vaccine doses were associated with a higher incidence of adverse events compared to second doses.
- Serious or fatal events were rare in the general population but more likely in elderly individuals with comorbidities.

## Abstract

Background: Adverse events following immunization (AEFI) must be reported and assessed to promote patient safety. This longitudinal study examined the nature and severity of adverse events reported after Covishield (Serum Institute of India, Pune, India) vaccine administration to North Indians in a tertiary care hospital.

Method: A retrospective evaluation of adverse drug reactions (ADRs) reported after Covishield vaccine administration in our hospital over 18 months was conducted. The assessment was carried out to analyze the pattern of ADRs reported by individuals receiving the Covishield vaccine from January 2021 to June 2022. Data such as age, gender, category, dose administered, type of ADR, duration of the event, medical history, and outcome of the reactions were collected. Each reported adverse event was assessed individually. Causality was determined using the WHO-UMC causality assessment scale. The data were analyzed and are expressed as mean ± standard deviation and percentage.

Results: A total of 14,590 individuals were vaccinated at our study center from January 2021 to June 2022. During this period, 146 AEFIs (1.0%) were reported at our ADR monitoring center, Employees' State Insurance Corporation Medical College and Hospital (ESIC MCH), Faridabad, India. The majority of AEFIs were systemic, were reported after the first dose, and had an onset within 12 hours after vaccination. Fever, injection site pain, drowsiness, headache, vomiting, swelling, tenderness, and body aches were the most commonly reported adverse effects. No significant relationships were observed between the administered vaccine dose and sex, severity, duration of the event, or outcome. However, the incidence of adverse events was greater with the first vaccine dose than with the second dose. The possibility of serious or fatal adverse events was lowest in the general population and higher in the elderly with comorbidities.

Conclusion: The data suggest that the Covishield vaccine had mild to moderate adverse effects on the study population. This pharmacovigilance study will complement safety data and aid in the benefit-risk analysis of adverse effects associated with the Covishield vaccine. Additionally, healthcare professionals should be encouraged to conduct further safety studies by establishing robust vaccine safety monitoring systems in hospitals. Continuing medical education and workshops should also be conducted to educate healthcare workers about active surveillance.