Christmas travel and a new coronavirus variant has health officials concerned that cases of the coronavirus will continue to surge across the country.

Dr. Peter Hotez, of the Baylor College of Medicine, says intensive care units across the country are being overwhelmed with patients.

"We're reproducing that Manhattan and New York City epidemic from March and April now times dozens of times," Hotez says.

More than seven million people went through American airport leading up to Christmas despite warnings from the Centers for Disease and Control that traveling can increase your chance of getting and spreading the coronavirus.

New travel restrictions will go into effect Monday, requiring all passengers coming from the United Kingdom to have proof of a negative coronavirus test within 72 hours of boarding.

Pfizer CEO Albert Bourla says he is cautiously optimistic that the company's vaccine will be as effective against the new variant of the virus discovered in the United Kingdom as it is against the previous one.

"We are testing to see if this new strain is equally sensitive to our vaccine and also would be neutralized by our vaccine," Bourla says.

Director of the National Institute of Allergies and Infectious Diseases Dr. Anthony Fauci estimates 70 to 85% of the country will need to be vaccinated to reach herd immunity.