Although many public health experts are expressing concern about the rising COVID cases in China, infectious disease experts have been increasingly worried about the XBB.1.5 variant. Recombinants of the BA.2 variant, XBB and XBB.1.5, together accounted for 44.1% of the total cases in the country for the week ended Dec. 31. For the week ended Dec.24, XBB.1.5 had made up 21.7% of the total cases. The XBB variant has been driving up cases in parts of Asia, including Singapore. It accounted for 3.6% of the total cases in the U.S. this week compared with 4.2% in the previous week.

---