Researchers in the US have discovered two new variants of coronavirus, one of which they say has became the dominant strain in the state of Ohio’s capital, Columbus, within just three weeks.

Scientists at Ohio State University said on Wednesday that they found the new variants from patients in the state, and warned the mutations could make the disease more easily spread from one person to another.

The researchers have not yet published their full findings, but the early results add to concerns that the disease could be mutating in different ways across the world without public health bodies noticing.

One of the new variants discovered in Ohio had mutated in the same way as the strain that has spread rapidly through the UK in recent weeks, although the Ohio researchers said they believed the mutation occurred in the US. The other was an entirely different mutation, which the Ohio researchers said had become dominant in Columbus during a three-week period in late December 2020 and early January.

Dan Jones, professor of pathology at Ohio State University and the lead researcher in the study, said: “We do think [the Columbus variant] has increased transmissibility compared with its parent variant. The presence of these strains does suggest that actions such as travel restrictions are not going to be enough to control the spread.”

Scientists believe new variants will appear in many places over the next year as the virus evolves to escape recognition in the bodies of people who already have partial immunity to the disease.

Two new strains have spread rapidly in several countries over the past few weeks — the B.1.1.7 strain first found in the UK and the 501v.2 variant discovered in South Africa, both of which have made the disease more infectious.

If a more transmissible strain takes hold in the US, it could compound the strain on hospitals, many of which are already stretched to capacity due to high infection rates across the country. A record 4,056 people died in the country from the virus on Tuesday, according to the Covid Tracking Project, with more than 131,000 people being treated in hospital.

The Ohio team of scientists said on Wednesday one of the variants they discovered had the same mutation as B.1.1.7. This strain was only discovered in one patient from Ohio, however, so they were unable to say how widespread it has already become.

The other strain, identified as COH.20G/501Y, has become prevalent in the state capital, and contains three genetic mutations never seen together in Covid-19. The scientists said the same mutation could be occurring independently in multiple parts of the world.

While researchers said they thought the mutations were making the virus more infectious, they did not yet know whether they were also making them less susceptible to vaccines.

“The big question is whether these mutations will render vaccines and current therapeutic approaches less effective,” said Peter Mohler, a co-author of the study and chief scientific officer at the Ohio State Wexner Medical Center.

“At this point, we have no data to believe that these mutations will have any impact on the effectiveness of vaccines now in use.”