Vaccine Breakthrough Infections among COVID-19 Vaccine Recipients: A Retrospective Observational Survey

Abstract

Background: The COVID-19 vaccine offers a high level of protection, reducing illness severity, hospitalisation, and death. However, it does not offer 100% protection from re-infection, and individuals have developed re-infections post COVID-19 vaccination, even after being fully vaccinated or having received additional booster doses. These are also known as vaccine breakthrough infections (VBIs).
Aim: This study aimed to determine the incidence of COVID-19 VBIs among the COVID-19 patients receiving care in a rural tertiary care hospital in India.
Methods: This retrospective study was conducted to determine the incidence of VBIs among all clinically suspected COVID-19 patients (N = 2,230) attending SGT Hospital, Haryana, India, from January to August 2022. Demographic characteristics, clinical data, co-morbidities, treatment, and vaccination details were retrieved, and the incidence of COVID-19 VBIs among the patients was analysed. A COVID-19 infection occurring 14 days following a primary series or a primary series with an additional booster dose of any COVID-19 vaccine was considered as VBI.
Results: A total of 261 out of the 327 SARS-CoV-2 RT-PCR positive cases had received COVID-19 vaccination. Among the vaccine recipients, 236 (72.3%) were identified as COVID-19 VBIs based on their vaccination
status: fully vaccinated (n = 229) or got an additional precaution dose (n = 7). There was a substantial difference in VBI incidence between those with a previous history of COVID-19 infections and those without. The majority of the VBIs (94.9%) showed mild to moderate symptoms without requiring hospitalisation.
Conclusion: Mild to moderate illnesses without requiring hospitalisation were seen in VBIs demonstrating COVID-19’s vaccine-induced protection. Additionally, those with natural SARS-CoV-2 infections had enhanced
hybrid immunity.

How to cite this article:
Devi L S, Sardar M, Sharma M. Vaccine Breakthrough Infections among COVID-19 Vaccine Recipients: A Retrospective Observational Survey. J Commun Dis. 2025;57(3):6-13.

DOI: https://doi.org/10.24321/0019.5138.202562