A new version of omicron is dominant in the U.S. The coronavirus subvariant known as BA.5 accounted for nearly 54% of the country’s Covid cases as of Saturday, according to the Centers for Disease Control and Prevention. A similar subvariant, BA.4, makes up 17% more.
“They’re taking over, so clearly they’re more contagious than earlier variants of omicron,” said David Montefiori, a professor at the Human Vaccine Institute at Duke University Medical Center. The two subvariants also appear to evade protection from vaccines and previous infections more easily than most of their predecessors.
Montefiori estimated that BA.4 and BA.5 are about three times less sensitive to neutralizing antibodies from existing Covid vaccines than the original version of the omicron variant, BA.1. Other research suggests that BA.4 and BA.5 are four times more resistant to antibodies from vaccines than BA.2, which replaced the omicron variant as the U.S.’s dominant version of the coronavirus in April.