Risk of SARS-CoV-2 reinfection is time- and variant-dependant, France, January 2021 to August 2022

Since the emergence of Omicron, reinfections with SARS-CoV-2 have been rising. We estimated the risk of SARS-CoV-2 reinfection in the widely vaccinated French population, from January to August 2022. At nine weeks post-infection, the relative risk of reinfection, primary infection with pre-Delta variants being the reference group, was estimated at 0.43 [95%CI 0.40-0.47] if the primary infection was attributed to Delta, 0.21 [95%CI 0.19-0.24] with BA.1 and 0.17 [95% CI 0.15-0.18] with BA.2, and rapidly waned overtime. After a BA.1 primary infection the protection was similar against BA.2 or BA.4/5 reinfection. ### Competing Interest Statement The authors have declared no competing interest. ### Funding Statement This study did not receive any funding ### Author Declarations I confirm all relevant ethical guidelines have been followed, and any necessary IRB and/or ethics committee approvals have been obtained. Yes The details of the IRB/oversight body that provided approval or exemption for the research described are given below: This study did not involve the human person. It was carried out by SpF using pseudonymised data collected by the Ministry of Health to manage the COVID-19 crisis. This processing of personal pseudonymised data was implemented in accordance with the legislative and regulatory prerogatives granted to SpF to fulfil its public interest mission and in compliance with the provisions of the GDPR. In this context, the opinion of an ethics committee was not required. I confirm that all necessary patient/participant consent has been obtained and the appropriate institutional forms have been archived, and that any patient/participant/sample identifiers included were not known to anyone (e.g., hospital staff, patients or participants themselves) outside the research group so cannot be used to identify individuals. Yes I understand that all clinical trials and any other prospective interventional studies must be registered with an ICMJE-approved registry, such as ClinicalTrials.gov. I confirm that any such study reported in the manuscript has been registered and the trial registration ID is provided (note: if posting a prospective study registered retrospectively, please provide a statement in the trial ID field explaining why the study was not registered in advance). Yes I have followed all appropriate research reporting guidelines and uploaded the relevant EQUATOR Network research reporting checklist(s) and other pertinent material as supplementary files, if applicable. Yes While all data used in this analysis were pseudonymised, the individual-level nature of the data used risks individuals being identified, or being able to self-identify, if it is released publicly. Requests for access to the underlying source data should be directed to Sante publique France and will be granted in accordance with the GDPR and French Law.