NHS England data showed there were 17,500 people working in older adult care homes across the Black Country and Staffordshire up to January 2 this year.
And this was down from the 17,838 recorded on July 18 last year – days before a 16-week "grace period" was introduced for care workers to get their first jab.
The number fell by 338 people, with England seeing an overall drop of around 17,000 over the same period. It is unclear how many left due to the vaccine policy.
Government rules stated care workers in England needed to have at least one vaccine dose by September 16 to continue working – and two by November 11.
In Wolverhampton, data shows there were 66 fewer staff working in older adult care homes. In Walsall, it was 27 fewer. In Staffordshire, 134 fewer. In Dudley, 124 fewer.
But Sandwell was among the minority of areas in England to see a rise in care home staff, with numbers rising by 13.
Meanwhile, the Government announced it is relaxing immigration rules to make up for “severe and increasing difficulties” with recruitment and retention in the care sector.
It follows a recommendation from the Migration Advisory Committee that care jobs be made eligible for the health and care visa, designed to help migrants get work visas to fill jobs where there are shortages.
Care providers are experiencing high vacancy rates and turnover, and pressure on staffing is being exacerbated by the spread of the Omicron variant.
Sam Monaghan, chief executive of MHA, the UK’s largest charitable care provider, said: “Essential care and support for older people is facing a staffing crisis the likes of which we have never seen before.
“The changes to immigration rules are a very welcome step forward in addressing the ongoing care staffing crisis.
“However, it will be some months before older people feel the benefit of these much-needed changes."
The Department for Health and Social Care said new starters can be deployed to work in care homes 21 days after receiving one dose of the vaccine and are required to get a second jab within 10 weeks.
Others not fully vaccinated may consist of those on maternity leave, long-term sickness or otherwise not currently deployed, a DHSC spokeswoman added.
They said £462.5 million had been provided for recruitment and retention, and the department was working with the care sector to encourage booster uptake.