CDC has also revised its past estimates for the week ending on December 18, when the agency announced that Omicron accounted for 73.2% of all new infections. The revised proportions show that the Delta variant caused 77% infections and Omicron 22.5% infections during that week.
The latest seven-day average of cases has increased to nearly 206,000 per day amid the growing prevalence of the Omicron variant, according to the CDC data.
Omicron was first detected in South Africa in November. South African health authorities, but also health experts from other countries, have said the Omicron variant is much more transmissible, but produces mild cases.