The coronavirus vaccine rollout has been extended to 36 and 37-year-olds as cases of the Indian variant have doubled in the space of one week.

Invitations are being sent following fears that the spread of the new Indian variant could jeopardise future plans to ease restrictions.

37-year-olds will be urged to book an appointment from today ( May 18 ) – with text messages to be sent to 36-year-olds on Wednesday.

At the same time, over 50s are having their second jabs brought forward on the advice of the Joint Committee on Vaccination and Immunisation (JCVI).

The moves comes amid continuing concern about the fast-spreading B.1.617.2 variant – first identified in India – with some scientists warning it could lead to a deadly new wave of the virus.

Surrey Comet: Vaccine rollout extended Vaccine rollout extended

The Times reported that ministers are considering contingency plans for local lockdowns if the strain cannot be brought under control.

NHS England national medical director Stephen Powis said there had already been 930,000 appointments made since the vaccination programme was opened up to 38 and 39-year-olds, and he urged people to come forward when called.

“Getting vaccinated is the most important step we can take to protect ourselves, our families and our communities against Covid 19, so when it is your turn to get your first or second dose please do so,” he said.

In the Commons on Monday, Health Secretary Matt Hancock said there were now 2,323 confirmed cases of the Indian strain in the UK, with 86 local authority areas recording at least five.

Worst hit have been Bolton and Blackburn with Darwen – where it is now the dominant strain with a total of 483 cases across the two areas – followed by Bedford.

Croydon has the highest number of cases within any south London borough, with at least 10 cases of the 'India Variant' of Covid-19 being detected, according to Public Health England (PHE).

Surrey Comet: Croydon vaccination clinicCroydon vaccination clinic

MORE: At least 10 cases of India variant reported in Croydon

Despite concerns the Indian variant is even more transmissible than the dominant Kent strain, the latest easing of lockdown restrictions went ahead as planned on Monday across most of England, Scotland and Wales.

It meant pubs and restaurants were able to welcome customers inside while people were able to socialise indoors and to hug family and friends outside their own households.

However ministers have warned the final lifting of lockdown restrictions in England, set for June 21, may have to be delayed if the new variant continues to spread.

Downing Street said on Monday that updates on plans for domestic coronavirus “passports”, announcements on easing social distancing requirements and further guidance on weddings, due later this month, could now be put back.

MORE: Indian Covid variant cases found in every SE London borough

The UK Government has rejected calls for the vaccine to be given to younger age groups in areas where the Indian variant was causing concern.

An analysis by the PA news agency found the Covid-19 rates in the worst hotspots were being driven by a sharp rise in cases among younger age groups.

Bolton, Blackburn with Darwen, and Bedford all have case rates among younger people that are running at a much higher level than those for older age groups.

However, Mr Hancock said they would continue to work down through the age groups, in line with the strategy set out by the JCVI as “the best way to save the most lives”.