WASHINGTON, Dec. 30 (Xinhua) -- The new COVID-19 variant that was discovered in Britain has been circulating undetected in the United States and transmitted person-to-person, according to the US Centers for Disease Control and Prevention (CDC) on Wednesday.

People walk past a CDC trailer near a COVID-19 testing station at Black Lives Matter Plaza near the White House in Washington, DC on October 9, 2020. (Photo: AFP)

The new variant was identified on Tuesday in a Colorado man in his 20s, with no travel history. It was the first time the variant strain has been identified in the United States.

Henry Walke, the CDC's COVID-19 incident manager, said on Wednesday the Colorado man did not have a travel history, which suggests this variant has been transmitted from person to person in the United States.

He said the new variant now circulating in the United States could further stress hospitals that are already overwhelmed with coronavirus patients.

Walke said the available data indicates that the new variant spreads "more easily and quickly than other strains," but it does not appear to cause more severe disease or increased risk of death.

Currently no close contacts of the infected Colorado man have been identified yet, but health officials are working on contact tracing, according to Colorado Governor Jared Polis.