Co-infection with multiple SARS-CoV-2 lineages can result in recombination of the
viral genomes and the emergence of novel, recombinant SARS-CoV-2 lineages.1–4 In January,
2022, the recombinant SARS-CoV-2 XBB lineage was first detected in India and incidence
is increasing in Asia and Europe.5 The XBB lineage is the result of recombination
of two omicron variant sublineages, BJ.1 and BM.1.1.1, and the breakpoint is located
in the gene for the spike protein (appendix p 10),6 which is responsible for host
cell entry and constitutes the target of neutralising antibodies.