What We Know About Omicron BA.4 and BA.5
Key TakeawaysTwo new versions of the Omicron variant, called BA.4 and BA.5, are taking hold in the U.S.Early studies and some real-world data suggest these variants are more transmissible than earlier Omicron variants and more likely to cause breakthrough infections.Key mutations in these variants can allow them to better infect cells and cause disease.Two new Omicron subvariants—BA.4 and BA.5—now account for 13% of new COVID-19 cases in the United States, a sizable leap from early May when the variants only accounted for 1%, according to data from the Centers for Disease Control and Prevention (CDC)....