Health officials say the first reported U.S. case of a new COVID variant is a Colorado National Guardsman in his 20s.

A second suspected case is also a guard member. Both say they haven't traveled.

Dr. Albert Ko, an infectious disease expert at Yale, says it's likely the new strain is from widespread community transmission.

The department of public health has been doing genomic sequencing and there are no signs of this variant yet here in Connecticut, according to Dr. Ko.

There is also no evidence to suggest the new mutation will mean an increase in severe illness or mortality, he says, but Dr. Ko warns the contagious nature of the mutation is concerning. He says it is up to 50% more contagious.

"If it's introduced here in Connecticut -- and it's likely it's already been spread through community transmission in the United States -- it's pretty inevitable that it will come here," he said. "We're going to have to double down on what we need to do to prevent COVID."

Pfizer and Moderna say their vaccines should be effective against new strains of the virus.

"We have a vaccine. We learned a lot about this virus. We know how to control the virus," said Dr. Ko.