Heterologous mRNA vaccine boosters induce a stronger and longer-lasting antibody response against Omicron XBB variant

The SARS-CoV-2 Omicron recombinant XBB subvariant was first detected in September 2022, and rapidly spread across South-East Asia, notably overtaking BA.5 to become the dominant variant in Singapore. As of December 2022, the prevalence of XBB is also increasing in the United States and Europe.1 XBB was likely formed from a recombination between strains from the BA.2.10 and BA.2.75 lineages, with the recombination breakpoint at position 446–460.2 XBB contains the R346T and N460K mutations which are shared with several other contemporary strains such as BQ1.1, BA2.3.20, and BA2.75. In addition, XBB carries several other sets of mutations, such as V83A, H146Q, Q183E, V445P, and F490S. Other subvariants derived from XBB harboring mutations such as H146del and D253G have now arisen as well and are rapidly spreading across the globe.