The more transmissible Omicron BA.4 and BA.5 subvariants are now dominant in all parts of the United States, with BA.5 again steadily expanding its scope, the Centers for Disease Control (CDC) said today in its latest weekly estimates.Cases held steady in lead-up to July 4Combined, the two subvariants make up more than 70% of recently sequenced samples, up sharply from 52.3% the previous week.Of the variants CDC is tracking, BA.5 now makes up 53.6%, and BA.4 makes up 16.5%.
The proportion of BA.2.12.1—first detected in New York—continues to decline.South-central states were the first to see BA.4 and BA.5 become dominant.
The two subvariants are more transmissible and have mutations linked to immune escape.Last week the Food and Drug Administration (FDA) recommended that vaccine companies update their booster shots to include BA.4 and BA.5, which is fueling increased cases in many countries.
Hospitalizations are rising as the volume of cases picks up, but so far, there's no sign that illnesses involving the subvariants are more severe.The updated boosters are expected to be available in early to mid fall, but in recent vaccine advisory group meetings, experts aired concerns about the possibility that more variants will emerge by that time.Currently, cases in the United States have been holding steady since late May at an elevated level.