Omicron subvariants BA.4 and BA.5 collectively account for 52 percent of U.S. COVID-19 cases, according to the CDC's latest variant proportion estimates for the week ending June 25.
BA.5 accounts for nearly 37 percent of cases and BA.4 nearly 16 percent. In line with what experts had been predicting, the sister variants have outpaced BA.2.12.1, which now accounts for 42 percent of cases. The variants are better at escaping antibody responses from both vaccination and prior infection than previous strains, according to recent findings from researchers at Beth Israel Deaconess Medical Center in Boston.
Two more COVID-19 updates:
1. Cases are expected to rise through early July, according to national modeling from Rochester, Minn.-based Mayo Clinic. Forecasts suggest average daily cases will jump from 94,147.7 June 25 to 119,150 by July 9. Hospitalizations and deaths are projected to remain stable.
2. After a daylong meeting, FDA advisers on June 28 recommended COVID-19 vaccines be updated to target omicron strains ahead of a fall booster campaign. The panel did not vote on which omicron subvariant the updated shots should target. If federal regulators choose to modify vaccines to target BA.4 or BA.5, it's unclear whether Moderna or Pfizer will have enough time to study and manufacture doses in time for a fall booster campaign.