Public Health England has recorded five cases of the Indian variant of Covid-19 in the Stroud District, as the strain becomes more dominant in the UK.
Early evidence suggests there may be an increased risk of hospitalisation from the variant, although more data is needed, according to the health agency.
Cases of the mutation, B.1.617.2, have risen by 5,472 since last week in the UK to 13,760.
Dr Jenny Harries, Chief Executive, UK Health Security Agency, said: “With this variant now dominant across the UK, it remains vital that we all continue to exercise as much caution as possible.
“The way to tackle variants is to tackle the transmission of COVID-19 as a whole. Work from home where you can, and practice ‘hands, face, space, fresh air’ at all times.
“If you are eligible and have not already done so, please come forward to be vaccinated and make sure you get your second jab. It will save lives.”
The Pfizer-BioNTech vaccine was 88 per cent effective against symptomatic disease from the B.1.617.2 variant 2 weeks after the second dose in a recent PHE study of 1,054 people.
Two doses of the AstraZeneca vaccine were 60 per cent effective against symptomatic disease.
The most affected areas remain Bolton, where cases of the Indian variant have risen by 795 to 2149, and Blackburn with Darwen which has seen 368 new cases, bringing it to 724 in total.
There are signs the transmission rate in Bolton has begun to fall and that the actions taken by residents and local authority teams have been successful in reducing spread.
Local teams have gone door to door in targeted areas on consecutive weekends to distribute test kits, share vital safety messages and encourage people to get the vaccine at a local drop-in centre.
PHE experts urged everybody to remain cautious as the country approaches the next stage of the roadmap.