Data from the U.S. Centers for Disease Control and Prevention indicated on Friday that the highly contagious Omicron XBB.1.5 subvariant is now to blame for over 40% of COVID-19 cases in the country, with the subvariant doubling from the previous week. Infectious disease specialists have been increasingly concerned about the XBB.1.5 variation, despite the fact that many public health professionals are worried about the rising COVID cases in China. Cases of the XBB subtype have increased in some Asian countries, including Singapore. This week, it made up 3.6% of all cases in the U.S., down from 4.2% the week before.