Health officials are investigating a new Covid variant detected in Yorkshire
Public Health England said current vaccines were still effective against the new variant.
Health officials are investigating a new Covid variant which has caused 49 cases of infection, mostly in Yorkshire and the Humber region.
Public Health England (PHE) has been monitoring the VUI-21MAY-01 or AV.1 variant since April.
PHE said there was "currently no evidence that this variant causes more severe disease or renders the vaccines currently deployed any less effective".
The agency said additional testing and tracing was being carried out.
Dr Kev Smith, from PHE, said scientists had been watching and sequencing the variant since the "strange combination of mutations" were spotted a few weeks ago.
"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 added.
Dr Smith said that PHE had classified it as a "variant under investigation" and would continue monitoring its spread through extra testing.
"At the moment, we don't think it's more infectious than the other coronaviruses that we are seeing around."
'Don't be alarmed'
Greg Fell, director of public health in Sheffield, said his team had been monitoring the new strain "as we do with all outbreaks across the city".
"Please don't be alarmed, we want you to continue doing what you have been for the past year. Follow the guidance, continue to wash your hands regularly and wear a mask indoors.
"Where cases have been identified, additional follow-up of cases, testing of contacts and targeted case-finding will be used to limit the spread of variants."