The prime minister says there's nothing yet to suggest the Indian variant will impact on England's roadmap out of lockdown, ITV News Health Editor Emily Morgan reports
A decision on whether final lockdown restrictions in England will be lifted on 21 June remains in the balance, with Boris Johnson saying "we will know a lot more in a few days' time" about the impact of the Indian variant.
The prime minister said "we have just got be cautious about how we approach it" and he promised to let people know "as much as we can as soon as we can".
However, he remained optimistic, telling reporters: "But, at the moment, we don't see anything conclusive that makes us think we have to deviate from the roadmap."
Text messages are being sent on Tuesday asking people to book an appointment – to be followed on Wednesday by 36-year-olds – as the rollout moves down the age groups.
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).
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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.
The Times reported that ministers are considering contingency plans for local lockdowns if the strain cannot be brought under control.
Environment Secretary George Eustice did not rule out local measures being introduced in response to the Indian variant.
Mr Eustice told ITV News if there were local pockets of the virus "then maybe you need to look at other sorts of localised restrictions".
He added: "But ideally we want to avoid that, we want to maintain the progress on the vaccine and then review the situation in a few weeks time."
Labour said the government should "listen to public health officials on the ground" who wanted to expand vaccinations to younger age groups.
Shadow Housing Secretary Lucy Powell also warned against local lockdowns, saying she was "reluctant to go down another road of tiering and local lockdowns".
She added "now we do have vaccines, lets use that tool as best we can first of all".
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.
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“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.
Meanwhile, The Daily Telegraph reported that EU ambassadors are set to sign off an a plan on Wednesday to allow British holidaymakers to travel to Europe without having to take a Covid test or quarantine.
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.
The authorities have responded by deploying “surge” vaccinations and testing in virus hotspots in an attempt to curb the spread of the disease.
However, Mr Hancock expressed frustration that of the 19 hospital cases in Bolton, the majority had not had the vaccine, even though they were eligible.
Bolton Labour MP Yasmin Qureshi criticised the Health Secretary's comments saying, "I don’t agree with him and I think it is quite a shame he and his government...try to blame other people for the fact that there is a rise in the variant in Bolton".
She added, when asked if there was vaccine hesitancy in area, "I have not seen any evidence of that".
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.
In Scotland, meanwhile tourism and hospitality bodies have called for urgent talks with First Minister Nicola Sturgeon over the decision to keep Glasgow in Level 3 restrictions over concerns about the spread of the Indian variant in the city.
Hospitality and entertainment businesses in Wales are also pressing the Welsh Government for clarity on when the remaining social distancing rules there can be lifted.
In Northern Ireland a decision is due this week on whether the next stage of easing can go ahead as planned on Monday.
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Meanwhile 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”.