The nation's top infectious disease expert, Dr. Anthony Fauci, expects the number of COVID-19 cases to climb following the discovery of the U.K. variant of the virus in California and Colorado.

"I'm not surprised that you have a case, and likely more cases in California – and we likely be seeing more reports from other states," said Dr. Fauci. "With all the travel, not only directly to the United States, but through other countries intermittently…I don't think that the Californians should feel this is odd. This is something that's expected.”

As of Monday, the United States started requiring airline passengers from Britain to get a negative COVID-19 test within three days of their trip. It's a decision Gov. Andrew Cuomo said was made too late.

"This is what happened last spring when the virus first came here,” said Gov. Cuomo. “It came from Europe…Federal government was wrong and the federal government was slow to move with the flights coming from Europe."

The governor was the first in the United States to require U.K. travelers be tested before flying into New York. A total of 120 countries made the same decision or banned travel from Britain altogether.

The state Department of Health is continuing to test COVID-19 specimens to see if the strain is in the state. So far, more than 4,300 have been analyzed and it has not been found.

While experts say the variant is more contagious, there is no data that shows it's deadlier.