The UK is investigating a new coronavirus variant first detected in the Yorkshire region of England. Public Health England said on Friday the new strain had been responsible for 49 new cases since April. Officials said there was "currently no evidence that this variant causes more severe disease or renders the vaccines currently deployed any less effective". Most of the cases were identified in Yorkshire and Humber in northern England. Dr Kev Smith from PHE said a “strange combination of mutations” was spotted a few weeks ago. He said additional testing and tracing was taking place to monitor the spread of the variant. "So far the people that we have identified are not particularly infectious, they're not really getting more sick than other cases of coronavirus and we're not seeing anything particularly worrying about it," he said. "At the moment, we don't think it's more infectious than the other coronaviruses that we are seeing around." The variant has been labelled a “variant under investigation”. It will progress to a “variant of concern” if it proves to be more infectious or capable of evading vaccine-induced immunity. Greg Fell, director of public health in Sheffield, said people in the city should not be unduly worried by the new variant. "Please don't be alarmed, we want you to continue doing what you have been doing for the past year. Follow the guidance, continue to wash your hands regularly and wear a mask indoors,” he said. Meanwhile, the Office for National Statistics said there are “early signs” of a potential rise in Covid-19 cases. The figures, published on Friday, show that around one in 1,110 people in private households in England had Covid-19 in the week to May 15 - up from one in 1,340 the previous week. However, Sarah Crofts, head of analytical outputs for the Covid-19 Infection Survey, said it was too soon to know whether the increase would be sustained. “This week there is a mixed picture of infection levels across the UK,” she said. “Although we have seen an early indication of a potential increase in England, rates remain low and it is too soon to say if this is the start of a trend.” Prime Minister Boris Johnson said he remained confident the final stage of England’s unlocking would proceed on June 21.