Heterologous inactivated virus/mRNA vaccination response to BF.7, BQ.1.1, and XBB.1

The emergence of highly immune-escape Omicron variants of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), such as BQ and XBB, has led to concerns about the efficacy of vaccines. Using lentivirus-based pseudovirus neutralizing assay, we showed that heterologous vaccination involving parental mRNA vaccine as a booster or second booster in individuals that received two or three doses of inactivated vaccines strongly augments the neutralizing activity against emerging Omicron subvariants, including BF.7, BQ.1.1, and XBB.1, by 4.3-to 219-folds. Therefore, a heterologous boosting strategy with mRNA-based vaccines should be considered in populations where inactivated vaccines were primarily used. ### Competing Interest Statement The authors have declared no competing interest. ### Funding Statement This work was supported by The European Unions Horizon 2020 research and innovation program (ATAC, 101003650, D.F.R., M.H., L.H., H.M., Q.P.H), the Center for Innovative Medicine at the Karolinska Institutet (FoUI-963219, Q.P.H), the Swedish Research Council (2019-01302, 2020-06116, Q.P.H), the Knut and Alice Wallenberg Foundation (KAW2020.0102, L.H., Q.P.H), and the Magnus Bergvalls Stiftelse (2022-111, F.Z). ### 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: The study was approved by the ethics committees in institutional review board (IRB) of Stockholm, and the Tehran University of Medical Sciences. I confirm that all necessary patient/participant consent has been obtained and the appropriate institutional forms have been archived, and that any patient/participant/sample identifiers included were not known to anyone (e.g., hospital staff, patients or participants themselves) outside the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 The data that support the findings of this study are available within the Article. All other data are available from the corresponding author upon reasonable request.