Legally forcing scores of workers to get a jab raises huge legal and moral questions. Ministers have previously called similar ideas “discriminatory”.

The Cabinet sub-committee paper warns that a “large” number of social care workers may quit if the change is made, and that successful lawsuits on human rights grounds could be possible. It makes clear that a similar legal requirement is being considered for some frontline healthcare workers, such as those on wards, but no decision on that has been taken.

The document, drafted by the Department of Health and Social Care, is about 15 pages long and entitled “Vaccination as a condition of deployment in adult social care and health settings”.

Its key line is understood to read: “The Prime Minister and the Secretary of State [Mr Hancock] have discussed on several occasions the progress that is being made to vaccinate social care workers against Covid-19 and have agreed – in order to reach a position of much greater safety for care recipients – to put in place legislation to require vaccinations among the workforce.”

The sentence makes it clear that both have decided in principle to change the law to require the vaccination of social care workers, even as the specifics are worked up. Government officials are discussing what the legislation would look like, with consultation on a final detailed proposal expected.

The legal change would be likely to affect England only, with health policy the remit of the devolved administrations in Scotland, Wales and Northern Ireland.

Care homes have been among the sectors hit hardest by the Covid pandemic. In the last year, around one in 14 of the population of UK care homes has died after contracting the virus.

The paper, described to The Telegraph in detail by numerous sources, outlines the scale of the problem of Covid vaccine take-up among care home workers which has led ministers to act.

It says the Scientific Advisory Group for Emergencies (Sage) set a benchmark of 80 per cent vaccination among staff and 90 per among residents for a care home to be deemed safe. Fewer than a quarter of homes in London currently meet that benchmark, according to the document – the lowest of any region in England. Even in better performing areas, such as the South-West, it is only around half.

Care homes have a relatively high proportion of black, Asian and minority ethnic workers. Vaccine take-up has been lower in BAME communities, according to government data.

Many care home workers are young, meaning they may not yet have had a Covid vaccine, and the paper says other possible factors include concerns over having the jab while pregnant and online misinformation about the vaccine.

A senior government source justified the move by saying: “Protecting the most vulnerable in our society from a deadly virus is obviously of critical importance.”

However, the legal and ethical questions posed are likely to be strongly debated in the coming months.

A key line in the paper is understood to read: “The most significant risk of a policy to require vaccination among the workforce is the potential impact on workforce numbers should social care workers choose to leave their roles in large numbers rather than be vaccinated.”

There are also legal risks. The document weighs up the respective merits of making the legal change via primary legislation or secondary legislation, which is quicker to pass. It is understood to warn that there would be a “high risk” of successful legal challenges on human rights and proportionality grounds if the change was made by secondary legislation.

Nadhim Zahawi, the vaccines minister, has previously said Covid vaccine “passports”, revealing people’s jab status, would be “discriminatory”. In the same BBC interview, given last month, Mr Zahawi said of the idea of mandating people to get Covid jabs: “That’s not how we do things. We do them by consent.”

A Cabinet Office spokesman said: “The review into Covid status certification is considering a range of issues. No final decisions have been made.”

David Sheppard, a senior associate in Capital Law’s employment and immigration team, which advises employers on Covid vaccination policies at work, said no similar law had been passed in more than a century.

Mr Sheppard said the closest equivalent was the 1853 Vaccination Act, which introduced compulsory vaccination for smallpox for newborn babies, and Acts passed in 1861, 1867 and 1871 to enforce that rule with fines.