Neutralization escape of Omicron XBB, BR.2, and BA.2.3.20 subvariants

New Omicron subvariants continue to emerge throughout the world. In particular, the XBB subvariant, which is a recombinant virus between BA.2.10.1.1 and BA.2.75.3.1.1.1, as well as the BA.2.3.20 and BR.2 subvar-iants that contain mutations distinct from BA.2 and BA.2.75, are currently increasing in proportion of variants sequenced. Here we show that antibodies induced by 3-dose mRNA booster vaccination as well as BA.1-and BA.4/5-wave infection effectively neutralize BA.2, BR.2, and BA.2.3.20 but have significantly reduced effi-ciency against XBB. In addition, the BA.2.3.20 subvariant exhibits enhanced infectivity in the lung-derived CaLu-3 cells and in 293T-ACE2 cells. Overall, our results demonstrate that the XBB subvariant is highly neutralization resistant, which highlights the need for continued monitoring of the immune escape and tissue tropism of emerging Omicron subvariants.

Automated summary

New Omicron subvariants are continuously emerging worldwide. The XBB subvariant, a recombinant virus between BA.2.10.1.1 and BA.2.75.3.1.1.1, as well as the BA.2.3.20 and BR.2 subvariants with distinct mutations from BA.2 and BA.2.75, are increasing in proportion. Antibodies induced by 3-dose mRNA booster vaccination and previous BA.1-and BA.4/5-wave infection effectively neutralize BA.2, BR.2, and BA.2.3.20, but have reduced efficiency against XBB. The BA.2.3.20 subvariant exhibits enhanced infectivity in lung-derived CaLu-3 cells and 293T-ACE2 cells. Continued monitoring of immune escape and tissue tropism of emerging Omicron subvariants is crucial.