People have been urged “not to go wild” after social restrictions were eased as one expert warned “we could go back to square one”.

Professor Anthony Harnden, deputy chairman of the Joint Committee on Vaccination and Immunisation (JCVI) said people should not behave in the same way as they did before the pandemic as he called for people to act cautiously for “a little bit more time”.

It comes after the Prime Minister urged people to continue to “exercise restraint” as beer gardens were packed and shoppers flocked to high streets after the latest round of the Government’s coronavirus restrictions were lifted in England on Monday.

Mr Johnson said on Tuesday that although vaccines had helped, lockdown restrictions had done “the bulk of the work” in reducing Covid-19 infections.

And he warned that the easing of lockdown restrictions will “inevitably” lead to more infections and deaths.

Asked about the remarks, Prof Harnden told BBC Breakfast: “I think he’s probably concerned, as I am, about the scenes in London that we saw of people actually enjoying the outside, pubs and then the crowded spaces – well, of course what that will do is push infection rates up.

“Every time that we ‘unlockdown’, we push infection rates up, and the danger of pushing infection rates up is we get much more transmission in the community.

“And new variant strains such as the South African strain – we really don’t want that to become prevalent in this country because of course the vaccines don’t work quite as well (against it).

“So I think he’s trying to be cautious with everybody.

“We will all want to get our lives back, we all want to enjoy ourselves again, but we must be cautious and do this slowly. Otherwise we’ll get back to square one.”

HEALTH Coronavirus
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He added: “We don’t need to behave in exactly the same way that we behaved before this pandemic, because if we’re just that little bit more cautious, just give it a little bit more time to get the complete population vaccinated, get infection rates down, we will be in a lot better place.

“Of course we can enjoy ourselves, but we just need to maintain that social distancing at the moment.”

And Prof Harnden told Good Morning Britain: “We’ve all been desperate for our freedoms – and it has been great this week when we can get out to the pub gardens and enjoy the outside space – but we must not go wild.

“If we start going wild and completely ignore all the basic rules, then we will see more transmission and things like the South African variant will become more prevalent.”

Meanwhile, the general secretary of pilots’ union Balpa, Brian Strutton, told Sky News that the travel sector has been “crippled” by the Covid-19 pandemic and called on the Government to provide details on when and where people can go on holiday.

And he said that the Government should subsidise the cost of any coronavirus tests that are required for future international travel.

And Luke Petherbridge, Abta’s director of public affairs, told the broadcaster that the travel industry feels “an overriding sense of frustration” with the “lack of detail” in the Global Travel Taskforce’s recent report on how international travel could safely return.

It comes as a “mix and match” trial assessing the use of two different types of Covid-19 vaccines in the same person was extended.

It is hoped that if people receive doses of different vaccine it may create a better immune response.

Being able to offer doses of different vaccines would also make it operationally easier if people need booster jabs in the future.

The trial, which is being led by the Oxford Vaccine Group at the University of Oxford, will look at how well people’s immune systems respond when the booster dose is a different type to their first vaccination.

During the trial, people over the age of 50 who have received the first dose of the Pfizer or AstraZeneca Covid-19 jab will be given a second dose of either the Pfizer, AstraZeneca, Moderna or Novavax vaccine.

In other developments:

– Office for National Statistics (ONS) figures suggest that across the UK, half the adult population would test positive for Covid-19 antibodies, which means they have either been infected or they have been vaccinated.

People testing positive for Covid-19 antibodies
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– Extensive surge testing is ongoing in parts of south London after a number of cases of the South African variant were identified.

– The number of vaccine doses administered in the UK has passed 40 million, of which nearly eight million are second doses.

– People aged 45 and over in England are being invited to make appointments for their vaccination.

– The number of positive Covid-19 tests was 2,472 and the Government said a further 23 people had died within 28 days of testing positive for Covid-19 as of Tuesday, bringing the UK total to 127,123.

– People over 16 in households of adults with a weakened immune system are to be prioritised for a jab in Wales, the devolved Government said.

Lockdown was further eased in England on Monday, with non-essential retail and pub beer gardens permitted to open, and Prime Minister Boris Johnson said there were no plans at present to change the road map out of lockdown.

The next steps forward in England’s plan to ease restrictions are due on May 17 and June 21.