Health Experts Warily Eye XBB.1.5, the Latest Omicron Subvariant

Three years into the pandemic, the coronavirus continues to impress virologists with its swift evolution. A young version, known as XBB.1.5, has quickly been spreading in the United States over the past few weeks. As of Friday, the Centers for Disease Control estimated that it made up 72 percent of new cases in the Northeast and 27.6 percent of cases across the country. The new subvariant, first sampled in the fall in New York State, has a potent array of mutations that appear to help it evade immune defenses and…