SARS-CoV-2 reinfection after previous infection and vaccine breakthrough infection through the second wave of pandemic in India: An observational study
Sachin Dhumal, Amar Patil, Ashwini More, Sujeet Kamtalwar, Amit D. Joshi, Anant Gokarn, Sumeet Mirgh, Puneeth Thatikonda, Prasanth Bhat, Vedang Murthy, Preeti Chavan, Amey Oak, Suvarna Gore, Atanu Bhattacharjee, Nikhil Patkar, Sadhana Kannan, Nitin Shetty, Anjali Rawat, Meera Sharad Achrekar, Bhakti Trivedi, Siddhartha Laskar, Pankaj Chaturvedi, Rajendra Badwe, Navin Khattry, Sudeep Gupta
Abstract
BACKGROUND: There are sparse longitudinal data on SARS-CoV-2 infection after previous infection and after partial or full vaccination. METHODS: This study of a cohort of healthcare workers used Kaplan-Meier analysis with appropriate definition of events and censoring and used Cox models to assess outcomes, with data cut-off on June 18, 2021. RESULTS: A total of 1806 individuals with median age of 32 (18-64) years, 1483 (82.1%) with at least one vaccine dose, 1085 (60.1%) with 2 vaccine doses, 408 (22.6%) with at least one episode of SARS-CoV-2 infection, and 6 (1.47%) with 2 episodes of infection were included in the analysis. At median follow-up of 38.4 weeks after first SARS-CoV-2 infection (n=408), the 52-week probability of reinfection was 2.2% (95% CI, 1.0-4.91%); and at median follow-up of 13.3 weeks after second dose, the 16-week probability of breakthrough infection was 5.6% (95% CI, 4.33-7.23%), which was significantly higher among those without previous SARS-CoV-2 infection versus with previous infection (6.4% vs 1.8%, p=0.016, adjusted Cox HR=3.49, 95% CI, 1.09-11.20, p=0.036) and females versus males (7.9% vs 3.8%, p=0.007, adjusted Cox HR=2.06, 95% CI 1.19-3.56, p=0.01). CONCLUSIONS: There was low probability of reinfection after previous SARS-CoV-2 infection and higher vaccine breakthrough infections among females and those without previous infection.