What is the XBB COVID variant?XBB is one of the “new class” of Omicron variants that are spreading fast right now, says Thomas Russo, M.D., professor and chief of infectious disease at the University at Buffalo in New York. That includes BQ.1.1, BQ.1, BQ.1.3, BA.2.3.20, and XBB, he says.
“XBB is a hybrid version of two strains of the BA.2 form of Omicron,” explains Amesh A. Adalja, M.D., a senior scholar at the Johns Hopkins Center for Health Security. It’s currently “spreading efficiently in Singapore,” he adds.
The variant was first detected in August 2022 in India, and has been detected in more than 17 countries since then, including Australia, Bangladesh, Denmark, India, Japan and the U.S., per Singapore’s Ministry of Health.