Health Secretary Sajid Javid is set to give a major announcement tonight on whether mandatory vaccines for NHS staff will dropped.
The rule was set to be enforced from April, which meant if staff hadn't had their first dose by this Friday they would not be double vaccinated in time.
Ministers are thought to have u-turned on the policy amid fears it will lead to a major staffing crisis.
Downing Street said Boris Johnson and Mr Javid have been reflecting on the policy as it was introduced when the Delta variant was the dominant strain.
Omicron is less dangerous than Delta. It is also more transmissible, meaning the vaccine has less of an effect on whether sufferers pass the virus to others.
The Prime Minister's official spokesman said: "Nothing has been set out yet, I think I’d defer to the Health and Care Secretary to set out exactly what is happening with regard to this."
He added that the “public would expect” us to keep policies such as these “under review”.
Data shows English regions including London, Leeds, Manchester and Birmingham are lagging behind in vaccinations, compared to the rest of the country.
In London, just 69% of Brits have had their first dose of the Covid jab with 44% having had their booster dose.
And the latest figures from NHS England show that 127,515 NHS and domiciliary care staff working in registered settings had not had a first dose of a Covid-19 vaccine as of January 23.
A senior NHS source told the Health Service Journal the mandatory policy will also be scrapped from social care.
Within this sector the policy was introduced back in November, and around 40,000 people lost their jobs.
Today, Number 10 refused to confirm if sacked care home staff be welcomed back. The PM's spokesman said: “I’m not in a position to pre-empt what the Health and Care Secretary is going to say”.
Access Social Care, a charity providing legal advice to the sector, said social care had been used as “the trial run for the NHS” when the Government “ignored” warnings about the impact on staffing in November.
Chief executive Kari Gerstheimer said: “If mandatory vaccinations are removed for the NHS, it is essential that they are also removed for social care.”
The Government's Covid-O Committee met this morning following warnings that some 100,000 healthcare workers would be forced out of their jobs because they had declined to take two doses of a Covid vaccine.
The PM has said he believes it is "absolutely clear" that NHS and social care workers should get vaccinated.
Speaking on a visit to the Port of Tilbury, in Essex, he said: "My view on NHS workers, everybody involved in looking after vulnerable people, all healthcare professionals should get a vaccine. That's absolutely clear.
"I think that Sajid Javid, the Health Secretary, is saying a bit more later on about how you might deal with different variants of coronavirus because they have different implications when it comes to transmission."
Tory MP Andrew Rosindell tweeted Mr Javid had made “the right decision”.
He said: “These free-thinking NHS workers’ jobs are saved and quite right too.
“Well done all those who had the courage to stand up for the values of a free society!”
