COVID-19 vaccine breakthrough infections among health care workers of a tertiary care center in North Kerala: a descriptive study

Abstract

Background: Vaccination against COVID-19 was started in India in January 2021 using ChAdOx1 nCoV-19 vaccine and health care workers were the first category to get vaccinated. The objective of the present study was to compare the characteristics of health care workers who had COVID-19 vaccine breakthrough infection with those who did not have breakthrough infection. Methods: This was a descriptive study conducted among 110 health care workers in a tertiary care center in North Kerala during 1, June 2021 to 31, July 2021. An equal number of health care workers who developed breakthrough COVID infection (55) and those who did not develop breakthrough infection (55) were included in the study. Results: The mean age of individuals who had breakthrough infection was 33.18 years (±9.52) and those of individuals who did not develop disease was 31.2years (±9.57). It was also observed that 21.8% of those with breakthrough infection and 10.9% of individuals without breakthrough infection had comorbidities. The study also found that individuals who took second dose of vaccine at an interval of 28-35 days from the first dose had higher chance of developing breakthrough infection compared to those who took second dose more than 35 days after first dose. Conclusions: The present study found that breakthrough infection was more common among those who took second dose of vaccine at an interval less than 35 days from the first dose. It was observed that numbers of individuals with comorbidities were higher among breakthrough infection group, but further studies are needed for better understanding.