UK Health Secretary Sajid Javid has said Covid-19 cases could rise to 100,000 a day, even as he defended the decision to end almost all lockdown restrictions, including mandatory masks in public places.
The backlash comes from doctors and some of the country's most high-profile mayors, who are in charge of implementing the easing of restrictions. Retailers and unions have also raised questions.
They are worried it will be difficult to enforce local mask rules if there is no national law behind it. Many want more discussions about getting ready for a return to rush hours and overcrowded commuter trains.
"I fully understand why many people will be anxious, and want to be cautious and that is why other protections remain in place but the vaccines are working," Mr Javid said.
“We can't live in a world where the only thing we are thinking about is Covid and not about all the other health problems, not about our economic problems, or education challenges, and we have to make use of a vaccine that is thankfully working," he said.
However, his message met some resistance.
London Mayor Sadiq Khan said the capital's transport chiefs – who are in charge of the Underground, buses and trains – and the government would hold further discussions.
"My mask protects you, your mask protects me," he tweeted. "The wearing of face coverings on public transport helps reduce the spread."
Liverpool Mayor Steve Rotherham said a YouGov poll showed 71 per cent of people wanted face masks to remain mandatory on public transport.
"The only opinions Boris Johnson seems to care about are those sat on his backbenches," he tweeted.
Greater Manchester Mayor Andy Burnham and West Yorkshire Mayor Tracy Brabin were also concerned about the ending of the legal requirement to wear masks on trains, trams and buses.
Dr Chaand Nagpaul, chairman of the British Medical Association, said it was "increasingly concerning" the government chose to ease restrictions fully despite warning signs that deaths and hospital cases are rising.
He called for mandatory mask wearing "until the rampant spread of infection has been brought under control and more of the population are fully vaccinated".
Dr Peter Openshaw, professor of experimental medicine at Imperial College London, said it was still important to wear a mask in scenarios such as on public transport or badly ventilated indoor spaces.
And Dame Clare Gerada, a London doctor, said she would wear a mask on the Tube, but for the wider public it was their personal "attitude to risk" that now dictated mask wearing.
For people with underlying conditions that could mean more steps to avoid unmasked travellers, Dame Clare added.
A number of retailers are calling on the Government for more detail before confirming their in-store policies for customers.
At Sainsbury's, chief executive Simon Roberts said he would consult with staff but the decision to wear a mask would be down to individual choice. Tesco is reviewing its mask policy while Morrisons and Aldi are asking for more guidance.
The retailers’ trade union, Usdaw, has called the government's move “too much too soon”.
“The government should not be weakening safety measures in shops at the same time as opening up other venues. There is no reason why requirements to wear face coverings and maintain social distancing in busy public areas like shops cannot continue,” said Paddy Lillis, general secretary of the shopworkers’ union, Usdaw.
And Jon Richards, assistant general secretary at Unison, the union for public sector workers, said that "removing most precautions at a stroke won't do anything to help reassure the thousands of nervous commuters” back onto public transport.
Mr Javid on Tuesday outlined his approach to mask wearing post-July 19.
"I will continue to carry a face mask with me for the foreseeable future and if I’m in a crowded place I will wear a mask, not least out of respect for others," he said.
He was also insistent that the July 19 easing of restrictions would go ahead as announced by Prime Minister Boris Johnson and that there could be 100,000 new cases a day into the summer.
"By the time we get to the July 19, we would expect case numbers by then to be at least double what they are now, so around 50,000 new cases a day," he said.
"As we ease and go into the summer, we expect them to rise significantly and they could go as high as 100,000 case numbers."
"One concern that is still there, and this is throughout the world, is that there will be new variants," Mr Javid said. "There is a risk, and I think it is a real risk, of some kind of vaccine-resistant variant. There is no sign of that yet anywhere, but I think it is something that no one can rule out."