Breakthrough infection with SARS-CoV-2 and its predictors among healthcare workers in a medical college and hospital complex in Delhi, India

Abstract

AbstractIntroductionThe study objective was to determine the breakthrough infection rate of Covid-19 (SARS-CoV-2) infection in those vaccinated with either BBV152 or AZD1222 (ChAdOx1-S) vaccine among healthcare workers (HCWs).MethodsA cross-sectional analysis was conducted a medical college and hospital complex in Delhi, India through telephonic interviews among HCWs who had received at-least one dose of a Covid-19 vaccine during January to March’ 2021. Breakthrough infections were operationally defined as occurrence of Covid-19 infection ≥14 days after administration of two doses of either Covid-19 vaccine.ResultsWe enrolled 325 HCWs with mean (SD) age of 29.1 (9.9) years including 211 (64.9%) males. Two seventy nine (85.8%) HCWs were fully vaccinated while 46 (14.2%) were partially vaccinated. There were 168 (51.7%) BBV152 and 157 (48.3%) AZD1222 (ChAdOx1-S) recipients.A total of 37 (11.3%, 95% C.I. 8.3, 15.3) breakthrough infections were observed in the HCWs. The median (IQR) time until incidence of Covid-19 breakthrough infection since receiving second dose of either Covid-19 vaccine was 47 (28.5, 55) days. Additionally, 20 (6.1%) non-breakthrough Covid-19 infections were recorded in the HCWs post vaccination with either a single dose of a Covid-19 vaccine or both doses but prior to a period of 14 days since administration of the second dose.Most breakthrough infection cases (94.4%) were mild and did not require supplemental oxygen therapy. HCWs without a history of natural Covid-19 infection and recovery prior to vaccination were 3.8 times more at risk to contract a Covid-19 infection or reinfection in spite of vaccination with at-least one dose of either Covid-19 vaccine.ConclusionNearly one in nine HCWs experienced a Covid-19 breakthrough infection in the present study.