More contagious Omicron subvariant becomes dominant in the U.S.
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According to the latest data from the Centers for Disease Control and Prevention (CDC), the BA.2 sub-variant of Omicron is estimated to account for more than half of COVID-19 cases in the U.S.
The genomic surveillance data for the week ending March 26 indicates that the prevalence of the variant has reached 54.9%, up from 39% a week ago. Meanwhile, the BA.1 sublineage accounted for the remainder of the cases analyzed.
CDCâs national genomic surveillance system studies thousands of genetic sequences and classifies the variants detected in COVID-19 specimens sent to the agency from commercially, locally, or state-owned laboratories.
Last week, the White House chief medical advisor Dr. Anthony Fauci said that despite its higher transmissibility, BA.2 subvariant is unlikely to cause more severe disease. 
BA.2 could become dominant in the U.S., he warned, predicting an âuptick in casesâ driven by the subvariant, but unlike the sharp increases seen with other variants.
Against this backdrop, the U.S. Food and Drug Administration (FDA) authorized the second booster shot of Pfizer (NYSE:PFE)/BioNTech (NASDAQ:BNTX) and Moderna (NASDAQ:MRNA) COVID-19 vaccines for people aged 50 years and older on Tuesday.