BA.4 and BA.5 now account for nearly 35 percent of U.S. cases, according to the CDC's latest variant proportion update. The strains have become known as "sister variants" of the original omicron strain.
BA.5 accounted for 23.5 percent of cases for the week ending June 18, according to CDC estimates released June 21. BA.4 accounted for 11.4 percent of cases. Together, the two strains are estimated to have made up 34.9 percent of cases that week. The omicron subvariant BA.2.12.1 is still dominant, accounting for 56 percent of cases.
For the previous week, the agency's estimates show BA.5 accounted for nearly 15 percent of cases and BA.4 at 8 percent. Earlier this month, health experts said they anticipate the sister variants to outpace BA.2.12.1
Three more COVID-19 updates:
1. COVID-19 modeling from Mayo Clinic Forecasts suggests daily average cases will jump from 73,783.9 on June 19 to 107,662 by July 3. The modeling suggests hospitalizations and deaths will remain stable through early July.
2. Infectious disease experts have warned a nearly 80 percent decrease in testing over the last three months may be disguising true infection rates. On April 12, the CDC tracked 964,373 tests. As of June 12, a little more than 210,000 tests were reported.
3. The CDC on June 18 backed the FDA's authorizations for Pfizer's and Moderna's vaccines for children younger than 5. More than 100 hospitals, pediatricians' offices and pop-up clinics plan to begin administering doses to the nation's youngest population this week.