Following news that the U.K. coronavirus strain has now been detected in California and Colorado, top health experts are stressing the need for mitigation measures to prevent virus spread.The coronavirus B.1.1.7. variant is said to be more transmissible than COVID-19, but it is not thought to be more virulent or resistant to vaccines and treatment. LIVE UPDATES: Today’s latest COVID-19 headlinesCalif. Gov. Gavin Newsom announced Wednesday that the new strain of the coronavirus was found in Southern California. Meanwhile, after a confirmed variant case, Colorado officials are investigating a second “highly suspicious” but not yet confirmed case of a coronavirus variant potentially found in another COVID-19-positive patient.U.S. Surgeon General Jerome Adams on Thursday assured Americans that the recently approved coronavirus vaccines appear effective against the new strain, however he urged caution ahead of the New Year’s Eve holiday.”You should take any worry that you have and understand that the vaccines still look like they’re going to work,” Adams told ABC’s “Good Morning America” co-hosts. “I’ve talked with Dr. Collins and Dr. Fauci about that as recently as yesterday. But a more contagious variant means it is more critical that we follow those basic public health measures, especially this New Year’s.”GET THE FOX NEWS APPAlso, Fox News medical contributor Dr. Nicole Saphier said the new contagious strain will be more difficult to control, though she noted there is already uncontained virus spread.”Ultimately it just means that it may be a little bit harder to contain this virus but we already have uncontained spread, which is why we have to continue the mask wearing, physical distancing and encouraging people to get vaccines,” Saphier told “Fox & Friends First” co-hosts Thursday.Fox News’ Morgan Phillips and Alexandria Hein contributed to this report.