I understand that all clinical trials and any other prospective interventional studies must be registered with an ICMJE-approved registry, such as. Due to the retrospective design of the study, informed consent was waived by the IRB, and all identifying details of the participants were removed before computational analysis.Īll necessary patient/participant consent has been obtained and the appropriate institutional forms have been archived. This study was approved by the MHS (Maccabi Healthcare Services) Institutional Review Board (IRB). The details of the IRB/oversight body that provided approval or exemption for the research described are given below: I confirm all relevant ethical guidelines have been followed, and any necessary IRB and/or ethics committee approvals have been obtained.

There was no external funding for the project. The authors have declared no competing interest. Individuals who were both previously infected with SARS-CoV-2 and given a single dose of the vaccine gained additional protection against the Delta variant. Conclusions This study demonstrated that natural immunity confers longer lasting and stronger protection against infection, symptomatic disease and hospitalization caused by the Delta variant of SARS-CoV-2, compared to the BNT162b2 two-dose vaccine-induced immunity.