Up to 300 care worker jobs could be lost in Somerset when Covid jabs become mandatory for care home staff.
The estimate has come from the leader of the county council, David Fothergill, who said the sector was already under pressure.
Thursday is the last day staff can get their first dose of the vaccine to be fully protected by the deadline.
A care home owner in Wellington said "we are losing very valued, experienced staff that can't be easily replaced".
From 11 November, it will be mandatory for anyone who works in a Care Quality Commission-registered care home in England to be fully vaccinated, unless they have a medical exemption.
Sandra Joyce, owner of Linden House Nursing Home in Wellington, said she expects to lose around 6% of her staff.
One has resigned, one is moving to the NHS where vaccinations are not compulsory and she suspects she will soon lose another.
She said they were losing "very, very valued, experienced staff" and they "can't be easily replaced".
She added: "It's not just the numbers. It's about the experience.
"I consider it's our duty to do everything in our power to protect people in our care, but you just can't make people do something that goes against the core of what they believe.
"I think it's a misjudged, mistimed and misinformed knee-jerk attempt to try to protect care."
To fill the posts, Ms Joyce has had to recruit people from overseas.
Care England, which represents care providers across England, estimates that up to 10% of staff have refused the vaccine.
Mr Fothergill said: "We are working with every one of them to try to understand what their reasoning is and to try to see whether there's anything that can be done.
"Of course some people can be switched into non front-line work, but not everybody.
"And when you talk of up to 300 jobs out of the care sector, that will begin to have an impact very quickly and probably this side of Christmas."
The new rules will not just apply to the staff who work in care homes every day, but people who provide occasional services like chiropodists and plumbers.
The government has said compulsory vaccinations in care homes will save lives and claim it is "a sensible and reasonable step" to protect care home workers and the people around them.