The government have repeatedly said the clinically extremely vulnerable should "use their own judgement" and that they should "contact their clinician" if they are concerned as Omicron cases soars.
It has also said the guidance for those who have shielded during the pandemic is the same as for everybody else with respect to Christmas parties, but on Wednesday the prime minister said those visiting people most vulnerable to COVID should be "cautious" about seeing them.
Charities have warned that the lockdown which began more than 18 months ago has never truly finished for many vulnerable, who have been consigned to their homes for a prolonged period of time.
Labour's shadow minister for disabled people, Vicky Foxcroft, said the guidance from Boris Johnson and his ministers lacked clarity and urged the government to provide the clinically extremely vulnerable with more support.
“The Prime Minister has lost his authority and the public are paying the price," Foxcroft told Yahoo News UK. “Many clinically extremely vulnerable people have struggled to get appointments with already overworked clinicians, so they can’t determine their risks, this is on top of a lack of clear guidance about whether they must now once again shield.
"Ministers need to get grip and ensure clinically extremely vulnerable people are assured and supported.”
On Wednesday, Boris Johnson told people to “think carefully” before going to events over the Christmas period at a Downing Street press conference.
“We’re not cancelling events, we’re not closing hospitality, we’re not cancelling people’s parties or their ability to mix," he said.
“What we are saying is think carefully before you go. What kind of an event is it? Are you likely to meet people who are vulnerable? Are you going to meet loads of people you haven’t met before? And get a test … make sure that there’s ventilation, wear a mask on transport and get a test before you go.
“We’re in a different environment, thanks to the boosters, from where we were last year, but we’ve got to be cautious and think about it whilst we wait for the benefits of the boosters really to kick in.”
The government introduced shielding at beginning of the pandemic to reduce the risk of those most vulnerable to the virus contracting it.
Many did not leave their homes for the best part of a year, unable to see friends or family until vaccines were rolled out and case numbers fell, with a significant cost to their emotional and mental wellbeing.
However, despite guidance for them ending on 19 July, government figures from November reveal 22% of the most clinically vulnerable have continued to shield.
At the press conference, Professor Chris Whitty said it is hoped the reintroduction of government guidance for the clinically extremely vulnerable to shield can be avoided if possible.
“Shielding came with some very serious downsides for the people involved in the shielding, including loneliness and mental health issues, practical problems," he said.
“It’s not an area we want to go down if there’s any way of avoiding doing so.”
Whitty also sought to highlight that the clinically extremely vulnerable qualify for four doses of the vaccine, and that antiviral drugs are also becoming available.
On visiting unvaccinated clinically extremely vulnerable relatives this Christmas, including the 300,000 of them that are housebound, a spokesperson for the prime minister said on Thursday: "It will need to be to individual circumstances and judgement.
"The public recognises that those deemed to be clinically extremely vulnerable are most at risk, and they would want to do everything possible using the guidance we’ve put out available and the mitigations - such as testing and vaccinations- to protect their loved ones at a time of high prevalence.
"But it will be down to individuals to decide what is right.”
It comes as data emerges that 26% of clinically extremely vulnerable people have not had a booster compared to just 6.7% who have not had a second jab - and 16.8% of over 80s have not had a third jab.
Asthma UK told Yahoo News UK that they keep their health advice regularly updated and that they understand that people will be "anxious" at this time.
Minesh Patel, head of policy at Macmillan Cancer Support, said "for many people with illnesses that effect their immune system such as cancer, the lockdown that began way back in March 2020 has never truly stopped".
Adding: "The act of wearing a mask, social distancing, testing before meeting up and getting a booster vaccination are all not just about protecting ourselves but protecting those at greater risk of serious illness from COVID-19.
“It is vital that the Government continues to be clear in its communication and guidance for those people who are in the clinically extremely vulnerable group.
"Many are already feeling the effects of being isolated from their loved ones for so long – a feeling that will only be heightened during the holiday season."
The UK recorded its highest ever number of new COVID-19 cases on Thursday at 88,376, breaking yesterday's record.
Watch: COVID-19: 'We're not locking down' - Boris Johnson denies 'stealth' shutdown but urges caution when socialising