COVID-19 Breakthrough Infections amongst ChAdOx1 nCoV-19 (Covishield) Vaccinated Health-Care Workers and Its Clinical Manifestations

Abstract

Introduction: Second wave of the COVID -19 pandemic had a significant impact on India with large number of populations getting affected by it. Pan -India COVID -19 vaccination was started on 16 January 2021. All the hospital Health Care Workers (HCWs) started receiving Covishield vaccine. By March 2021, all the HCWs received 02 dosages of the vaccine. It was the time when the second wave of COVID-19 started in India. This study was conducted to investigate the occurrence and severity of breakthrough COVID -19 infection (BCI) amongst fully vaccinated HCWs. Materials and Methods: This prospective observational study was conducted at a single multispecialty COVID-19 dedicated hospital on fully vaccinated HCWs who developed BCI. A total of 981 HCWs were enrolled and observed them for six months from March -September 2021 for occurrence of BCI. The outcome measures included percentage of fully vaccinated HCWs developing BCI. The BCI according to various demographic variables was studied. Clinical profile, duration between last dose of vaccine and BCI and requirement of mechanical ventilation were analysed. Results: Out of 981 fully vaccinated HCWs, 97 developed BCI. Amongst one -fifth of them were asymptomatic. Fever and cough were the prominent symptoms. Two HCWs developed COVID -19 pneumonia. None required oxygen supplementation or mechanical ventilation. There was no death observed amongst these COVID -19 infected HCWs. Discussion: BCI occurred in 9.88% fully vaccinated HCWs. They were primarily minor and did not lead to severe disease. Overall, Covishield prevented severe infection in HCWs, leading to decreased ICU admission and deaths.