The UK has “increasing confidence” that Covid-19 vaccines work against the Indian variant of the virus, the health secretary has said.
Scientists believe that the variant is more transmissible and cases of it nearly tripled to 1,313 in the past week in England.
But Matt Hancock said early lab data showed vaccines remained effective.
He said the majority of those in hospital in Bolton – a hotspot for the Indian variant – were unvaccinated.
The health secretary said that the variant, known as B.1.617.2, was “relatively widespread in small numbers” in most of the country.
It comes as England is due to move to stage three of the government’s roadmap for easing lockdown on Monday, with socialising in groups of six indoors as well as some international travel to be allowed.
On Friday Prime Minister Boris Johnson warned the variant could pose “serious disruption” to the final stage of lockdown easing in England on 21 June.
Speaking on the BBC’s Andrew Marr Show, Mr Hancock said that it was “quite likely” that the variant would become the dominant strain in the UK.
He said: “What that reinforces is the importance of people coming forward for testing and being careful because this isn’t over yet.
“But the good news is because we have increasing confidence that the vaccine works against the variant, the strategy is on track – it’s just the virus has gained a bit of pace and we’ve therefore all got to be that bit more careful and cautious.”
Mr Hancock also defended the easing of lockdown rules in England from Monday, saying the government’s strategy was to “replace the restrictions with vaccination” as the first line of defence against the virus.
But Prof Adam Finn, a member of the Joint Committee on Vaccination and Immunisation, told the BBC that even though rules were being eased in most parts of the UK on Monday people should be “very cautious about mixing”.
A decision on whether all legal restrictions could be ended next month would be made on 14 June, Mr Hancock said.
He also confirmed over-35s in England would be able to book an appointment for their Covid-19 jabs in the coming week.
Three things explain why the government and experts are sounding so cautious.
Firstly, we’ve known for a while that the vast majority of Covid infections take place when people mix indoors, and that’s exactly what will be allowed with the next phase of lockdown easing in England on Monday.
Secondly, the vaccination programme, for all its success, is still a long way from reaching all adults with two doses. And, even when it does, it can’t guarantee 100% protection for everyone.
Thirdly, the more transmissible Indian variant is casting an unsettling shadow over the roadmap out of lockdown.
The guidance is to be concerned rather than to panic. The variant may well be less hazardous than feared but key questions about it remain unanswered.
In any event, the hope is to vaccinate many more people as quickly as possible and in the meantime to highlight the risks.
The advice can be summed up like this: think twice about lingering for hours in a crowded room that has little fresh air.
In Bolton there are 18 people in hospital with coronavirus, with the majority of those not having the jab despite being eligible, the health secretary said.
He added that five people had ended up in hospital having had one jab, while there was one there who had received both doses but was “frail”.
Surge testing is taking place in targeted areas across England where virus variants have been found, including postcodes within several London boroughs, Sefton, Worcestershire, and Nottingham.
Prof John Edmunds, who sits on the government’s Scientific Advisory Group for Emergencies, told Andrew Marr people should be “concerned but not panicking” about the new variant.
“We are in a much, much better position than we were when the Kent variant started spreading,” he said, pointing to hospitals having few Covid patients and the vaccine programme being in place.
On Saturday the number of patients in hospital with Covid dropped below 1,000 for the first time in eight months, down from the peak of nearly 40,000 in January.
Despite concerns about the Indian variant, coronavirus restrictions across England, Scotland and Wales are due to be relaxed from Monday.
Curbs lifting across the devolved nations vary, but there will be a greater degree of indoor mixing allowed and more hospitality venues will be able to reopen.
Northern Ireland is due to review its restrictions later this month.
Which rules are changing on Monday?
In England, six people or two households can meet indoors, with pubs, restaurants and cafes allowed to serve customers inside. Up to 30 people can meet outdoors. Museums, cinemas, theatres and sports stadiums can reopen, and indoor exercises resume. People can travel abroad to green list countries without needing to quarantine when they return.
Up to six people from a maximum of three households can socialise indoors in Scotland, and entertainment venues such as cinemas, theatres and bingo halls can reopen. Alcohol can be served indoors in hospitality venues until 22:30, and international travel will be allowed in line with England’s rules.
In Wales, pubs, cafes, bars and restaurants reopen for indoor service, with groups of up to six from six households permitted to meet. All holiday accommodation can reopen fully, as can indoor visitor attractions, such as galleries and museums. International travel can resume in line with the traffic light system.
Northern Ireland is reviewing its restrictions on 20 May, with the hope more restrictions will be lifted on 24 May.
Labour’s Yvette Cooper, chair of the Home Affairs Select Committee, said she felt worried about Monday’s easing but recognised that businesses had prepared to open and that the government said vaccines were effective against the variant.
She said it was right to concentrate on increasing vaccinations, testing and help fill the financial “gap” so people can self-isolate.
On Saturday, the British Medical Association (BMA) said it had serious concerns about the decision to continue with the easing of lockdown restrictions.
Meanwhile, minutes from a meeting of government scientific advisers, held on Thursday, said that “an even faster increase can be expected if measures are relaxed” in areas where the Indian variant is already spreading.
And if the variant was 40-50% more transmissible than the current dominant type, they warned proceeding to step three of England’s roadmap on Monday would likely “lead to a substantial resurgence of hospitalisations (similar to, or larger than, previous peaks)”.