SARS-CoV-2 reinfection after previous infection and vaccine breakthrough infection through the second wave of pandemic in India: An observational study

• Published in: International journal of infectious diseases Vol. 118; pp. 95 - 103
• Main Authors: Dhumal, Sachin, Patil, Amar, More, Ashwini, Kamtalwar, Sujeet, Joshi, Amit, Gokarn, Anant, Mirgh, Sumeet, Thatikonda, Puneeth, Bhat, Prasanth, Murthy, Vedang, Chavan, Preeti, Oak, Amey, Gore, Suvarna, Bhattacharjee, Atanu, Patkar, Nikhil, Kannan, Sadhana, Shetty, Nitin, Rawat, Anjali, Achrekar, Meera, Trivedi, Bhakti, Laskar, Siddhartha, Chaturvedi, Pankaj, Badwe, Rajendra, Khattry, Navin, Gupta, Sudeep
• Format: Journal Article
• Language: English
• Published: Canada Elsevier Ltd 01.05.2022; The Author(s). Published by Elsevier Ltd on behalf of International Society for Infectious Diseases; Elsevier
• Subjects: Adult; ChAdOx1 nCoV-19; ChAdOx1 nCoV-19 vaccine; COVID-19 - epidemiology; COVID-19 - prevention & control; COVID-19 Vaccines; Female; Humans; Male; Middle Aged; Pandemics; Reinfection; Reinfection - epidemiology; Reinfection - prevention & control; SARS-CoV-2; Vaccine breakthrough infection; ChAdOx1 nCoV-19 vaccine; SARS-CoV-2; Reinfection; Vaccine breakthrough infection
• ISSN: 1201-9712; 1878-3511
• DOI: 10.1016/j.ijid.2022.02.037

•Cohort study in employees of a cancer center in India with complete follow-up.•Period of study spanning the second wave of SARS-CoV-2 pandemic in India.•Very low (2.2%) reinfection up to 1 year after previous infection with SARS-CoV-2.•Vaccine breakthrough infection rate of 5.6%; ChAdOx1 nCoV-19 vaccine in majority.•Higher vaccine breakthrough infections in females and without previous SARS-CoV-2 infection. There are sparse longitudinal data on SARS-CoV-2 infection after previous infection and after partial or full vaccination. 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. 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). There was low probability of reinfection after previous SARS-CoV-2 infection and higher vaccine breakthrough infections among females and those without previous infection.