Risk and severity of SARS-CoV-2 reinfections during 2020–2022 in Vojvodina, Serbia: A population-level observational study

Snežana Medić; Cleo Anastassopoulou; Zagorka Lozanov-Crvenković; Vladimir Vuković; Nataša Dragnić; Vladimir Petrović; Mioljub Ristić; Tatjana Pustahija; Zoran Gojković; Athanasios Tsakris; John P.A. Ioannidis

The Lancet Regional Health. Europe (Sep 2022)

Risk and severity of SARS-CoV-2 reinfections during 2020–2022 in Vojvodina, Serbia: A population-level observational study

Snežana Medić,
Cleo Anastassopoulou,
Zagorka Lozanov-Crvenković,
Vladimir Vuković,
Nataša Dragnić,
Vladimir Petrović,
Mioljub Ristić,
Tatjana Pustahija,
Zoran Gojković,
Athanasios Tsakris,
John P.A. Ioannidis

Affiliations

Snežana Medić: Center for Disease Control and Prevention, Institute of Public Health of Vojvodina, Novi Sad, Serbia; Faculty of Medicine, University of Novi Sad, Novi Sad, Serbia
Cleo Anastassopoulou: Department of Microbiology, Medical School, National and Kapodistrian University of Athens, Athens, Greece
Zagorka Lozanov-Crvenković: Department of Mathematics and Informatics, Faculty of Science, University of Novi Sad, Novi Sad, Serbia
Vladimir Vuković: Center for Disease Control and Prevention, Institute of Public Health of Vojvodina, Novi Sad, Serbia; Faculty of Medicine, University of Novi Sad, Novi Sad, Serbia
Nataša Dragnić: Center for Informatics and Biostatistics, Institute of Public Health of Vojvodina, Novi Sad, Serbia
Vladimir Petrović: Center for Disease Control and Prevention, Institute of Public Health of Vojvodina, Novi Sad, Serbia; Faculty of Medicine, University of Novi Sad, Novi Sad, Serbia
Mioljub Ristić: Center for Disease Control and Prevention, Institute of Public Health of Vojvodina, Novi Sad, Serbia; Faculty of Medicine, University of Novi Sad, Novi Sad, Serbia
Tatjana Pustahija: Center for Disease Control and Prevention, Institute of Public Health of Vojvodina, Novi Sad, Serbia; Faculty of Medicine, University of Novi Sad, Novi Sad, Serbia
Zoran Gojković: Faculty of Medicine, University of Novi Sad, Novi Sad, Serbia; Clinical Center of Vojvodina, Novi Sad, Serbia
Athanasios Tsakris: Department of Microbiology, Medical School, National and Kapodistrian University of Athens, Athens, Greece
John P.A. Ioannidis: Departments of Medicine, Epidemiology and Population Health, Biomedical Data Science, and Statistics, Stanford University, Stanford, CA, USA; Corresponding author.

Journal volume & issue: Vol. 20
p. 100453

Abstract

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Summary: Background: Data on the rate and severity of SARS-CoV-2 reinfections in real-world settings are scarce and the effects of vaccine boosters on reinfection risk are unknown. Methods: In a population-level observational study, registered SARS-CoV-2 laboratory-confirmed Vojvodina residents, between March 6, 2020 and October 31, 2021, were followed for reinfection ≥90 days after primary infection. Data were censored at the end of follow-up (January 31, 2022) or death. The reinfection risk was visualized with Kaplan-Meier plots. To examine the protective effect of vaccination, the subset of individuals with primary infection in 2020 (March 6–December 31) were matched (1:2) with controls without reinfection. Findings: Until January 31, 2022, 13,792 reinfections were recorded among 251,104 COVID-19 primary infections (5.49%). Most reinfections (86.77%, 11,967/13,792) were recorded in January 2022. Reinfections were mostly mild (99.17%, 13,678/13,792). Hospitalizations were uncommon [1.08% (149/13,792) vs. 3.66% (505/13,792) in primary infection] and COVID-19 deaths were very rare (20/13,792, case fatality rate 0.15%). The overall incidence rate of reinfections was 5.99 (95% CI 5.89–6.09) per 1000 person-months. The reinfection risk was estimated as 0.76% at six months, 1.36% at nine months, 4.96% at 12 months, 16.68% at 15 months, and 18.86% at 18 months. Unvaccinated (OR=1.23; 95%CI=1.14–1.33), incompletely (OR=1.33; 95%CI=1.08–1.64) or completely vaccinated (OR=1.50; 95%CI=1.37–1.63), were modestly more likely to be reinfected compared with recipients of a third (booster) vaccine dose. Interpretation: SARS-CoV-2 reinfections were uncommon until the end of 2021 but became common with the advent of Omicron. Very few reinfections were severe. Boosters may modestly reduce reinfection risk. Funding: No specific funding was obtained for this study.

Published in The Lancet Regional Health. Europe

ISSN: 2666-7762 (Online)
Publisher: Elsevier
Country of publisher: United Kingdom
LCC subjects: Medicine: Public aspects of medicine
Website: https://www.thelancet.com/journals/lanepe/home

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