A senior British scientist said the UK has reached an “unacceptable” level of coronavirus cases as pressure from medical experts for tougher measures to be brought in escalated.
The government continued to rule out moves for Plan B social restrictions.
Prof Peter Openshaw, a member of the New and Emerging Respiratory Virus Threats Advisory Group, condemned what he called the government's “mixed messaging” and said measures such as mask wearing and working from home would “lead to a pretty good reduction” in the number of cases.
“What we’re facing at the moment is unacceptable, we’ve got roughly 1 in 55 people infected, which is an astonishingly high rate compared to most other west European countries”, he told BBC Radio 4’s Today programme.
“I don’t think it’s a binary 'go for Plan B or nothing', it’s very clear that the measures that are in included in Plan B are sensible and not very disruptive.
“It’s not problematic to give clear leadership about the use of face masks and working at home if you can is also not particularly disruptive for many people.
“Those measures are likely to lead to a pretty good reduction in the really unacceptable number of cases that we’ve got at the moment.”
On Monday, UK Health Secretary Sajid Javid said new measures to control the spread of coronavirus would be “kept under review” but said he did not think Britain had "reached the point where [they need] to be activated".
He said whether the government introduced “Plan A or Plan B has got nothing to do with Cop26”, after suggestions No 10 Downing Street was holding off on bringing in restrictions because of the imminent climate conference in Glasgow.
“It’s got everything to do with getting the very best clinical advice from our world-leading scientists,” he added.
Mr Javid last week said new cases could reach 100,000 a day but Downing Street insisted there was still spare capacity in the health service and that Plan B would be activated only if the National Health Service came under “significant pressure”.
“The purpose of setting up a clear plan, not just with respect to Covid but with other winter challenges, was to make clear how we make these decisions”, he said.
Mr Javid accepted the wider health system was under “huge pressure” as he outlined plans to invest £6 billion ($8.25bn) to help clear the NHS waiting list backlog of around 5.7 million patients.
“I'm not going to pretend that we're not under huge pressure," he said. "There is a lot of pressure in the system and that is something we work on on a daily basis with our friends in the NHS to see what we can be doing.”
In a separate interview with Sky News, Mr Javid said he believed “we’ll have a normal Christmas” and urged people to come forward and get their vaccine and booster shots. He said he was “leaning towards” mandatory vaccination for NHS staff.
The UK Department of Health recorded 39,962 additional cases of coronavirus on Sunday. It reported 328,287 people have tested positive for Covid-19 in the past seven days, an increase of nearly 10 per cent on the previous week.
On Thursday, cases passed the 50,000 mark in what was Britain's highest daily infection total since mid-July.
Prime Minister Boris Johnson, who has resisted pleas from health leaders for tighter restrictions despite the rising number of cases, said vaccines would get the country through the winter and out of the pandemic.
The government has launched a media blitz encouraging people to get booster jabs and is urging those not yet vaccinated to book an appointment to do so.
“Yesterday was the biggest day yet for Covid booster jabs: more than 325,000 people getting vital protection,” Amanda Pritchard, chief executive of NHS England, posted on Twitter on Sunday.
“In the past three days over 800,000 people have had their booster jab.”
Jeremy Brown, professor of respiratory medicine at University College London Hospitals, who sits on the Joint Committee for Vaccination and Immunisation, said that it was not essential to reduce the interval for booster jabs from six to five months.
Asked whether the interval should be reduced, Prof Brown told Sky News: “No, I don’t think that’s absolutely necessary at the moment.
“We’re trying to make sure the booster occurs at a time when the vaccine efficacy has waned to a certain degree – not much but enough to warrant a booster – and also to ensure that we have a long-term protection that persists for as long as possible, and the gap makes a difference.”
He said about eight million people were eligible for boosters but only five million of them have had their shot.
If the interval was reduced this could mean "that extra three million people who need the booster – the most vulnerable – will get their booster delayed rather than actually having it on time”.
Vaccines Minister Maggie Throup said Plan A was “working” and “where we need to be”.
“The public has been very patient in doing what we’ve asked them to do,” she said on LBC radio.
“And I think Plan A has actually opened up people’s lives and that’s so important, because if we do need to take further measures I’m sure they’ll have appreciated exactly the freedoms we’ve been able to offer them at this time.”
Prof Adam Finn, who is also on the JCVI, warned against complacency in what he said was a “worsening” situation.
He said people should test themselves, wear masks and avoid crowds in enclosed spaces to prevent “a real meltdown”.
Prof Finn said that while vaccines were very effective at stopping people from getting seriously ill, they were not as effective at stopping infections altogether or stopping the virus from spreading.
“They do have an effect on that, but they’re not by themselves going to be enough at the present time to keep the spread of the virus under control,” he said.
“And we do need to see people continuing to make efforts to avoid contact, to avoid transmission and to do other things as well as get vaccinated if we’re going to stop this rise from going up further,” he told Trevor Phillips On Sunday on Sky News.
“I would like to re-emphasise the fact that the vaccine programme by itself, in the current situation, even if things go optimally, is not, in my opinion, enough to bring things under control,” Prof Finn said.
“We do need to have people using lateral flow tests, avoiding contact with large numbers of people in enclosed spaces, using masks, all of those things now need to happen if we’re going to stop this rise and get things under control soon enough to stop a real meltdown in the middle of the winter.”
His comments came after another prominent adviser to the government on Covid-19 said he was “very fearful” there would be another “lockdown Christmas”, as he urged the public to do everything possible to reduce transmission of the virus.
Dr Katherine Henderson, president of the Royal College of Emergency Medicine, said people should try to minimise the need for healthcare resources.
“We didn’t go into the pandemic in a great place in emergency care. We didn’t have enough beds then,” she told Sky News.
“The problem is that things are worse at the moment, so we need everybody to be as careful with the healthcare resources as they possibly can be and try to minimise the need for healthcare resources.
“If we’ve got 8,000 patients in hospital who are suffering with Covid, if we didn’t have those patients that would be another 8,000 beds in the system.
“So, every bed that gets filled by a patient with Covid in a sense is in a hospital bed with a potentially avoidable disease and that’s what we need people to focus on if we want to get through the elective backlog.”
Meanwhile, The Observer newspaper reported that the UK Health Security Agency contacted local authorities on Friday to canvass their level of support for the “immediate roll-out of the winter plan – Plan B”.
“We don’t comment on leaks. It is part of UKHSA‘s role to provide advice to the government on the continuing response to the pandemic,” a UKHSA spokeswoman said.
“UKHSA recognises the significant past and continuing importance of local authorities and their directors of public health in managing the pandemic.
“We will continue to consult with them and learn from the experience of local communities to help us to protect the nation’s health.”
