Neutralising immunity to omicron sublineages BQ.1.1, XBB, and XBB.1.5 in healthy adults is boosted by bivalent BA.1-containing mRNA vaccination and previous Omicron infection.

Competing Interests: All authors declare they have no competing interests. All data (anonymised) and full R code to produce all figures and statistical analysis presented in this Correspondence are available online on Github: https://github.com/davidlvb/Crick-UCLH-Legacy-XBB-2023-03. This study was sponsored by University College London Hospitals. This study was undertaken at University College London Hospitals and University College London, which received a proportion of funding from the National Institute for Health Research University College London Hospitals Biomedical Research Centre and Clinical Research Facility. ECW, VL, and BW are supported by the Biomedical Research Centre funding scheme. This study was supported jointly by the Biomedical Research Centre and core funding from the Francis Crick Institute, which receives its funding from Cancer Research UK, the UK Medical Research Council, and the Wellcome Trust. DLVB and RB are additionally supported by the Genotype-to-Phenotype (G2P) National Virology Consortium via UK Research and Innovation and the UK Medical Research Council. The funders of the study had no role in the study design, data collection, data analysis, data interpretation, or writing of the report. The corresponding authors had full access to all the data and the final responsibility to submit for publication.