The BA.2 subvariant of omicron was estimated to be more than half, or 54.9 percent, of the coronavirus variants circulating in the United States as of Saturday, the U.S. Centers for Disease Control and Prevention said on Tuesday.
A resurgence of Covid-19 cases in parts of Asia and Europe has raised concerns that another wave could follow in the United States.
Despite the rise of the highly transmissible BA.2 subvariant, health experts in the United States believe that a new wave of infections appears unlikely as overall infections are declining from January’s record highs.
As of Saturday, the seven-day moving average of U.S. Covid-19 cases was 27,895, up about 4 percent from a week earlier.
Last week, top U.S. infectious disease official Dr. Anthony Fauci said that although he does not expect a major surge, he would not be surprised to see a rise in cases owing to the increasing dominance of the BA.2 subvariant.
Most people in the United States are now considered to be in low Covid transmission, according to new CDC guidelines introduced last month that emphasized hospital capacity over case counts.
The CDC estimates that BA.2 made up 39 percent, revised up from 34.9 percent, of circulating variants in the country for the week that ended March 19, according to a CDC model that estimates proportions of circulating variants.
The CDC has in the past revised its estimates as it gets more data.