More than 4,000 people died of COVID-19 in the United States on Thursday, a new one-day pandemic record for the nation as its outbreak continues to surge at an alarming rate. With over 3,700 deaths on Friday, the nation's seven day average for daily deaths has passed a record high of 3,000, signalling worse days ahead.

A White House coronavirus task force report, obtained by NBC News, theorizes that the nation's worsening coronavirus outbreak could be due to a new COVID mutation, similar to the ones discovered in the United Kingdom and South Africa, circulating throughout the population.

"This fall/winter surge has been at nearly twice the rate of rise of cases as the spring and summer surges," the task force's document, which was sent to states on Jan. 3, states according to NBC News. "THis accelerating suggest there may be a USA variant that has evolved here, in addition to the U.K. variant that is already spreading in our communities and may be 50% more transmissible."

The U.S. Centers of Disease Control and Prevention, however, thinks it is highly unlikely that multiple variants of the coronavirus have evolved at the same time.

"Researchers have been monitoring U.S. strains since the pandemic began, including 5,700 samples collected in November and December," Jason McDonald, a spokesperson for the C.D.C., said in a email to CNBC. "To date, neither researchers nor analysts at C.D.C. 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."

Nevertheless, the outbreak in the U.S. is surging at a rapid rate. Over the past seven days, the U.S. has reported over 1.69 million new infections with a seven-day rolling average of 241,500 cases per day, according to data for the COVID Tracking Project.

Amid the record case numbers, the U.S. is looking to boost its vaccine distribution and administration rate. Earlier this week, the Department of Health and Human Services announced two upcoming by the C.D.C. to provide over $22 billion to states and local governments to support the nation's pandemic response efforts. These include $19 billion in grants that support testing, contact tracing, containment and mitigation efforts and over $3 billion for various vaccination campaigns.

Even if the U.S. is experiencing it own COVID variant, the Pfizer (PFE  )-BioNTech (BNTX  ) appears to be effective against a key mutation in the more infectious variant first discovered in the U.K. and South Africa, according a study conducted by the U.S. pharmaceutical giant and scientists at the University of Texas Medical Branch.

In the research, which has yet to be peer-reviewed, showed that the Pfizer-BioNTech shot worked to neutralize the spike protein mutation N501Y, which researchers found to be on more transmissible variants of the virus.