The White House coronavirus task force said there could be a new variant of the virus that evolved in the U.S. and is driving spread, according to a document obtained by NBC News.
The strain variant, in addition to the U.K. variant, is already spreading in communities and may be 50% more transmissible, according to the report that was issued to states on Jan. 3.
The CDC issued a statement saying it has not seen the emergence of a highly contagious new U.S. variant of the coronavirus, unlike variants in the U.K. and South Africa. It noted, however, that there are probably many variants emerging across the globe.
The task force said the recent spike in cases has been at nearly twice the rate seen in the spring and summer seasons, according to the report. The U.S. is recording at least 228,400 new Covid-19 cases and at least 2,760 virus-related deaths each day, based on a seven-day average calculated by CNBC using Johns Hopkins University data. The U.S. reported its deadliest day Thursday with more than 4,000 deaths.
"This acceleration suggests there may be a USA variant that has evolved here, in addition to the UK variant that is already spreading in our communities and may be 50% more transmissible," the report said. "Aggressive mitigation must be used to match a more aggressive virus; without uniform implementation of effective face masking (two or three ply and well-fitting) and strict social distancing, epidemics could quickly worsen as these variants spread and become predominant."
"It is highly likely there are many variants evolving simultaneously across the globe," Jason McDonald, a spokesman for the CDC, said in an email to CNBC. He added that there's a "strong possibility" there are variants in the U.S., but it could be weeks or months before officials identify a particular variant that is "fueling the surge in the United States similar to the surge in the United Kingdom."
"Researchers have been monitoring U.S. strains since the pandemic began, including 5,700 samples collected in November and December," he said. "To date, neither researchers nor analysts at CDC have seen the emergence of a particular variant in the United States as has been seen with the emergence of B.1.1.7 in the United Kingdom or B.1.351 in South Africa."
Representatives for the Department of Health and Human Services did not return CNBC's requests for comment.
Few details were provided about the new U.S. strain in the report, including how long it has been circulating. In recent weeks, the U.S. has ramped up its genomic sequences to try and detect other strains.
Dr. Scott Gottlieb, a former commissioner of the Food and Drug Administration, told CNBC on Friday that the new strain the White House task force has found appears to be behaving like the one circulating in the United Kingdom.
But he told "Closing Bell" the new strain isn't the same as the U.K. one, known as B.1.1.7, adding, "if it was we'd recognize that because we're looking for it."
Public health officials have been worried about the new strain of the virus found in the U.K. The CDC has identified at least 52 Covid-19 cases with the B.1.1.7 mutation in the U.S., according to data posted on the agency's website last updated on Thursday. However, the CDC warns that its numbers "do not represent the total number of B.1.1.7 lineage cases that may be circulating in the United States" and may not match the figures reported by local officials.
So far the CDC only shows California, Florida, New York, Colorado and Georgia with cases of the B.1.1.7 variant, but other states like Connecticut, Pennsylvania and Texas announced the arrival of the strain in their states on Thursday.
New York Gov. Andrew Cuomo warned Thursday the new strain from the U.K. could force the state into another economic shutdown if it spreads unchecked and weakens the state's hospitals.
"In the U.K., it overtook everything in three weeks," Cuomo said. "If the U.K. spread catches on in New York, hospitalization rate goes up, the hospital staff is sick, then we have a real problem and we're at shutdown again."
In the task force report issued over the weekend, officials urged states not to delay immunization of those over 65 and vulnerable to severe disease.
"No vaccines should be in freezers but should instead be put in arms now; active and aggressive immunization in the face of this surge would save lives," the task force said.
Michael Osterholm, a member of President-elect Joe Biden's Covid-19 advisory board, said Tuesday that the U.S. would likely see more new variants of the virus emerge.
Osterholm, an epidemiologist and director of the Center for Infectious Disease Research and Policy at the University of Minnesota, said in an interview with CNBC that the strain that was discovered in the U.K. is "a very big concern."
"And it's the first of what will likely be a number of these strains that are emerging as we're at this point in the pandemic," he added.