Around seven in 10 Covid patients in intensive care units across hospitals in the Midlands are not vaccinated, a health boss has said.
Medical experts have said those who are not fully vaccinated against coronavirus are facing increased risks of being hospitalised.
In the Midlands, around 20% of eligible people have yet to have their booster - with only a third of under 30-year olds having taken up their booster to date.
They say it puts themselves at risk, as protection from the first two doses reduces over time and needs a top-up to provide increased protection against Omicron.
Those in-charge for public health in the Midlands have said with Covid cases increasing they are seeing more people being admitted to hospital - which continues to put "avoidable pressure" on hospitals.
Interim Regional Director of Public Health for the Midlands, Professor Mike Wade said the numbers speak for themselves.
He said: "We know that specific groups are putting themselves at risk by not taking up the vaccine – including men under 40 and women who are pregnant or breastfeeding.
"The vaccines are safe, and they greatly reduce the chance of getting seriously unwell, being hospitalised, or even dying, if you catch Covid-19."
In the last seven days there were 83,163 cases of Covid-19 reported in the West Midlands, with a rate of around 1,395 per 100,000.
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More than 2.65 million people in the Midlands had vaccinations in December and more than 100,000 of them were first doses.
People are being urged to get their vaccine whether it be their first or third to get the protection needed against serious illness from Covid-19.
Regional Medical Director for NHS England and NHS Improvement in the Midlands, Dr Nigel Sturrock said: “We have all read that Omicron is mild but I’m hearing from doctors in hospitals that it isn’t mild for everybody – patients who have no immunity to Covid-19 are becoming very ill indeed."