Seven youngsters have been kept away from Denbigh High school after coming down with "mumps like" symptoms following five suspected cases being reported among pupils on Friday.

We have seen outbreaks of mumps throughout the country before but we've only had a handful of cases in north Wales since 1994

Dr Richard Roberts

North Wales Health Authority says that on Tuesday 60% of pupils at the school took up the offer of the vaccine.

The authority said that some of the 870 youngsters who refused the booster had already received the second dose of MMR.

Confirmation of the suspected outbreak is not expected for up to three weeks.

But the authority has already moved to dispel possible fears about the triple vaccine.

Health chiefs said any unfounded links between the vaccine and autism are irrelevant because autism never appears in older children.

There have only been a total of five other cases of mumps in the authority area since the introduction of the combined measles, mumps and rubella (MMR) vaccine eight years ago.

But because of their age the majority of pupils at Denbigh High had only had the single-dose vaccine.

This latest suspected outbreak follows recent confirmed outbreaks of the more serious measles in London and northern England.

Uptake of the controversial vaccination has fallen across the UK amid fears - so far unproven - of links between the vaccine and bowel disease and autism in children.

The cases we are dealing with will be off school until they're well but the vaccine offers good protection

Dr Richard Roberts

Last week North Wales Health Authority revealed the number of children being given the MMR vaccine had fallen because parents were concerned about the possible side effects.

Dr Richard Roberts, consultant in the authority's public health department, said: "We have seen outbreaks of mumps throughout the country before, but we've only had a handful of cases in north Wales since 1994."

Health officials have urged pupils, who have not yet had the full two doses of the MMR vaccine, to have the full dose as soon as possible.

They say it is quite safe for three doses to be given.

Seldom serious

A team from the authority visited the school on Tuesday to offer the vaccination.

One vaccine of MMR provides 90% protection against mumps but two doses would provide 99% protection against mumps, measles and rubella.

Mumps usually causes fever and swelling of the saliva glands beneath the ear and gets better within seven to 10 days.

"Although mumps is seldom serious, it can be unpleasant," said Dr Roberts.

He added: "The cases we are dealing with will be off school until they're well but the vaccine offers good protection."