Adverse events following ChAdOx1 nCoV-19 Vaccine (COVISHIELD) amongst health care workers: A prospective observational study

BACKGROUND: During ongoing COVID-19 pandemic, researchers worked enormously to develop effective vaccines against COVID-19 infection. Two Indian-made vaccines [Covishield (ChAdOx1 nCoV-19) and Covaxin] were granted Emergency Use Authorization. India launched its COVID-19 vaccination drive starting with healthcare workers (HCW). Aim of the study was to evaluate adverse events following immunization (AEFI) amongst the HCW with two doses of Covishield vaccine. We also evaluated association of AEFI according to sex, profession and age groups. METHODS: A prospective observational study was conducted in a tertiary care COVID dedicated hospital of Southern India from 16 Jan - 15 Apr 2021. Nine hundred and eighty one HCW who received 2 doses (4 weeks apart) were enrolled. Active and passive surveillance was conducted after 48 hours, and at days 8,15, 22 and 28 for both doses. The rate of AEFI for each dose was determined. Incidence and association of AEFI with various demographic variables was determined. RESULTS: 1020 non-serious and two serious AEFI (altered sensorium) were reported within 48 hours of first dose. Two hundred and twenty non-serious AEFI were reported within 48 hours of second dose. No AEFI was reported after 15 days for both the doses. We found no association of AEFI with sex and profession ( p >0.5). Significant association of AEFI was found with age ( p <0.01) CONCLUSION: Short-term AEFI were predominantly observed in first 48 hours. Incidence decreased in subsequent weeks with no occurrence after 15 days in both doses. Symptoms were mild in severity and short-lived. No serious AEFI attributable to vaccines were reported.