Outbreaks of measles have been detected in the east of England in the last year, it can be revealed, as it was announced that the UK has lost its measles-free status.

Public Health bosses said the vast majority of cases had involved children who were not fully immunised and urged parents to make sure vaccines were up to date before school term time began in two weeks time.

There are 8,000 five year olds in the east of England who are not fully vaccinated.

And health bosses warned this meant some four and five year olds are starting school at unnecessary risk of serious diseases compared to the majority of their classmates.

Dr Shylaja Thomas, consultant in public health medicine and lead for screening and immunisation at Public Health England, East of England, said: "It's a real concern that so many young children in our region could be starting school without the full protection that the NHS childhood immunisation programme offers for free.

"We're particularly concerned about children being at greater risk of measles. We've seen outbreaks of this disease in the east of England in the past year and we're continuing to see outbreaks of the disease occurring in communities across the country, many linked to visiting European countries over the summer holidays. The vast majority of those affected are not fully immunised and vaccine preventable diseases spread more easily in schools. It's crucial that children have maximum protection as they begin to mix with other children at the start of their school journey."

It comes as prime minister Boris Johnson took aim at anti-vaxxers - those who oppose vaccinating children.

He said: "The UK generally has a great record on fighting measles but for the first time, we're suddenly going in the wrong direction and we're seeing an increase of about 230 new cases of measles just in the first few months of this year.

"I think there's complacency on the part of parents about the need to get that second vaccine but also, I'm afraid, people have been listening to that superstitious mumbo jumbo on the internet, all that anti-vax stuff and thinking that the MMR vaccine is a bad idea.

"That's wrong.

"Please get your kids vaccinated because it's not just the right thing for them, but also of course it is the right thing for the whole population because it might not be your kid that gets it, it could be somebody else's."

The MMR jab vaccination rate has risen in recent years in Norfolk, up from a low of 87.5pc of children having their first dose by the age of two in 2010/11. But it is still below the 95pc benchmark at 94.3pc.

Just 91.6pc of children had the full two doses by five years old.

Hobart High School in Loddon has issued a warning to parents following three confirmed cases of illness at the school.

In the UK, dose one of the MMR vaccine, which protects against measles, mumps and rubella, is usually given to infants at around 12 months of age.

A second dose is given before school, usually at three years and four months of age, to ensure best protection. Two doses of MMR in a lifetime are needed for a person to be considered fully protected.

Although usually a mild illness in children, measles can be more severe in adults.

The initial symptoms of measles develop around 10 days after a person is infected. These can include cold-like symptoms, sore, red eyes that may be sensitive to light, and a fever.

And a few days later, a red-brown blotchy rash will appear. This usually starts on the head or upper neck, before spreading outwards to the rest of the body

Symptoms usually clear up in seven to 10 days. Complications include pneumonia, ear infections, brain inflammation (encephalitis) and even death.