Healthcare workers administer free Covid-19 tests to people in their cars in the parking lot of the Columbus West Family Health and Wellness Center in Columbus, Ohio on November 19, 2020.Stephen Zenner | AFP | Getty ImagesResearchers in Ohio said Wednesday that they’ve discovered two new variants of the coronavirus that likely originated in the U.S. — one of which quickly became the dominant strain in Columbus, Ohio, over a three-week period in late December and early January.Like the strain first detected in the U.K., the U.S. mutations appear to make Covid-19 more contagious but do not seem like they will diminish the effectiveness of the vaccines, researchers said.The Ohio State University researchers have not yet published their full findings, but said a non-peer-reviewed study is forthcoming. Jason McDonald, a spokesman for the Centers for Disease Control and Prevention, said in a statement to CNBC that the agency is looking at the new research.One of the new strains, found in just one patient in Ohio, contains a mutation identical to the now-dominant variant in the U.K., researchers said, noting that it “likely arose in a virus strain already present in the United States.” However, the “Columbus strain,” which the researchers said in a press release has become dominant in the city, includes “three other gene mutations not previously seen together in SARS-CoV2.””This new Columbus strain has the same genetic backbone as earlier cases we’ve studied, but these three mutations represent a significant evolution,” Dr. Dan Jones, vice chair of the division of molecular pathology at Ohio State and lead author of the study, said in a statement. “We know this shift didn’t come from the U.K. or South African branches of the virus.”The mutation found in the dominant new strain in Columbus — COH.20G/501Y — “may be occurring independently in multiple parts of the world during the past few months,” the researchers said.Peter Mohler, chief scientific officer at the Ohio State Wexner Medical Center and co-author of the forthcoming study, said there’s no data to indicate that the new strain will impact the effectiveness of vaccines.”It’s important that we don’t overreact to this new variant until we obtain additional data,” he said in a statement. “We need to understand the impact of mutations on transmission of the virus, the prevalence of the strain in the population and whether it has a more significant impact on human health.The Ohio researchers will hold a press briefing on their discovery at 11 a.m. ET.The White House Coronavirus Task Force warned states earlier this month that there may be a “USA variant” circulating. The hypothesis, which The New York Times reported was pushed by task force coordinator Dr. Deborah Birx, was based on how severe the U.S. outbreak has become in recent months. The CDC said in a statement last week that it has not yet detected a new variant in the U.S. unrelated to already-discovered strains.This story is developing. Check back here for updates.