The Omicron variant is currently causing about 13 percent of new COVID-19 cases in New York and New Jersey, according to new data from the Centers for Disease Control and Prevention (CDC).
Nationwide, the variant has gone from causing 0.4 percent of new cases in the week ending December 4, to 2.9 percent of cases in the week ending December 11.
CDC Director Dr Rochelle Walensky said on the TODAY Show that the variant is 'more transmissible' and 'rapidly becoming the more predominant strain' in other countries.
As cases increase in the U.S. - with 120,000 new cases reported daily - experts have advised Americans to get vaccinated, utilize tests, and mask up in indoor public spaces.
As Omicron spreads rapidly through the U.S. - especially in New York and New Jersey, CDC Director Dr Rochelle Walensky and other experts recommend getting vaccinated, including a booster shot. Pictured: Vaccination in the Bronx, New York, January 2021
In the New York and New Jersey region, Omicron (purple pie chart slices) has caused 13% of new Covid cases in the past week, according to CDC estimates
The highly contagious Omicron variant was first detected in South Africa and Botswana in late November.
Since then, it's caused a major case surge in South Africa, overtaking the Delta variant.
The variant has also been identified around the world: as of Tuesday, more than 13,000 cases have been detected in 77 countries.
That includes more than 180 cases in the U.S., with the variant identified in 35 states.
At a press briefing last week, Walensky said the Delta variant remained the country's top concern, as it was causing over 99 percent of cases in the U.S.
But new estimates from the CDC - released Tuesday morning - indicate that the Omicron variant is spreading rapidly in the U.S., and may overtake Delta within weeks.
Omicron caused 2.9 percent of new Covid cases nationwide, in the week ending December 11.
That's a six-fold increase from the previous week, in which Omicron caused 0.4 percent of new Covid cases.
The CDC's updated data also indicate that Omicron was already spreading in the U.S. by Thanksgiving, causing 0.1 percent of cases nationwide in the week ending November 27.
'It is more transmissible, and we're seeing that in other countries as well, that it's rapidly becoming the more predominant strain, but I want to emphasize that we have the tools now,' said CDC Director Rochelle Walensky of the new variant on TODAY Tuesday morning.
'The science is still evolving, it's still early, but what we're seeing in some of these other countries is doubling times of about every two days or so,
