Newer, more contagious Omicron subvariants become dominant in U.S.
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Latest estimates from the Centers for Disease Control and Prevention (CDC) indicated on Tuesday that two highly transmissible sub-variants of Omicron accounted for more than 50% of all coronavirus cases.
CDCâs sequencing data for the week ending June 25 shows that BA.4 and BA.5 subvariants of the Omicron made up about 16% and 37% of cases compared to ~12% and ~25% a week ago, respectively.

Early this month, the European Union's disease prevention agency said that the BA.4 and BA.5 are spreading faster than other variants of the coronavirus, which could lead to more hospitalizations and deaths.
According to latest CDC estimates, Omicron lineage BA.2 and its spinoff, BA.2.12.1, made up ~6% and ~42% of all cases.
Leading vaccine makers, Pfizer (NYSE:PFE)/BioNTech (BNTX) and Moderna (MRNA), have noted that their Omicron-adapted COVID vaccine candidates were found to generate a lower antibody response against BA.4 and BA.5.