Breakthrough Sars-Cov-2 infection after Covid-19 vaccination - A retrospective observational clinico-epidemiological study from North-Western India

ABSTRACT

Introduction: Mass vaccination is considered one of the most crucial weapons in fighting against the ongoing COVID-19 pandemic. However, the occurrence of breakthrough infections (BTIs) has questioned the vaccine effectiveness of the currently available vaccines. The present study aimed to determine the breakthrough SARS-CoV-2 infections in the vaccinated population and to compare the clinic-epidemiological profile and outcomes between breakthrough cases and unvaccinated SARS-CoV-2 positive cases. Methods: This retrospective case-control study was conducted between April 15, 2021, and June 15, 2021, in a zonal military hospital in Jaipur. We evaluated individuals with BTI as cases which were SARS-CoV-2 positive after 14 days of the second dose of vaccine and unvaccinated SARS-CoV-2-positive individuals as control. The clinical and demographic data was collected from the Indian Council of Medical Research and specimen referral forms were filled out for all persons who had undergone testing for SARS-CoV-2. The outcome of positive cases in terms of discharge and deaths were collected from hospital records. Results: A total of 162 breakthrough COVID 19 infections and 925 unvaccinated positive confirmed controls were recorded within the study duration. The majority of cases presented with mild infection in both case (80.2%) and control groups (72.4%). The risk of hospitalization and occurrence of moderate to severe disease was 2.3 and 4 times more in the non-vaccinated group as compared to the vaccinated group, respectively. No mortality was reported among the breakthrough cases. Interpretation and Conclusions: Despite the occurrence of BTIs, the benefits of vaccines are far greater. Our findings suggest that vaccination is associated with a lower risk of hospital admission, severe disease, and mortality against COVID-19. © 2022 Medical Journal of Dr. D.Y. Patil Vidyapeeth ;Published by Wolters Kluwer - Medknow.