Omicron subvariant makes up nearly one quarter of new Covid cases in US
This data is up from around 1 in 10 new cases just a week prior, Xinhua news agency reported.
The BA.2 variant is spreading fast in the country, with infections nearly doubling every week, according to CDC data.
Early studies showed that BA.2 may be up to 30 per cent more transmissible than the original Omicron.