Risk of symptomatic reinfection in second COVID-19 wave in individuals previously exposed to SARS-CoV-2

 Mattia Manica, Serena Pancheri, Piero Poletti, Giulia Giovanazzi, Giorgio Guzzetta, Filippo Trentini, Valentina Marziano, Marco Ajelli, Maria Grazia Zuccali, Pier Paolo Benetollo, Stefano Merler, Antonio Ferro

doi: https://doi.org/10.1101/2021.04.14.21255502

This article is a preprint and has not been certified by peer review [what does this mean?]. It reports new medical research that has yet to be evaluated and so should not be used to guide clinical practice.

PDF: https://www.medrxiv.org/content/10.1101/2021.04.14.21255502v1.full.pdf

Abstract

To what extent infection with SARS-CoV-2 protects against subsequent reinfection or symptomatic reinfection is still unclear. In this cohort study, we analyzed surveillance records of COVID-19 cases identified between June 2020 and January 2021 in five Italian municipalities, where 77.7% of the entire population was screened for IgG antibodies in May 2020. We compared the risk of observing symptomatic infections in two mutually exclusive groups defined by the initial serological response. We estimated that the cumulative incidence of identified symptomatic infections in the IgG negative and positive cohorts was 2.67% (95%CI: 2.12%-3.37%) and 0.14% (95%CI: 0.04%-0.58%), respectively. The adjusted odd ratio of developing symptomatic infection in individuals previously exposed to SARS-CoV-2 was estimated at 0.054 (95%CI: 0.009-0.169). Quantifying protective immunity against COVID-19 disease elicited by natural infection with SARS-CoV-2 is essential to inform strategies for controlling the pandemic in the forthcoming months.

Competing Interest Statement

MA has received research funding from Seqirus. The funding is not related to COVID-19. All other authors declare no conflict of interest.

Funding Statement

MM,PP,GGu,FT,VM and SM acknowledge funding from the European Commission project MOOD (H2020-874850). The contents of this publication are the sole responsibility of the authors and don't necessarily reflect the views of the funders.

https://www.medrxiv.org/content/10.1101/2021.04.14.21255502v1