Medical experts fear Britain is heading for a major measles outbreak because of the high numbers of parents deciding against the triple measles, mumps and rubella (MMR) vaccine.
In some parts of the UK, a quarter of school-age children are not being vaccinated because research has indicated the vaccine may be linked to autism and the bowel disorder Crohn's disease.
Public health experts say the vaccine is perfectly safe, but many parents are confused by the conflicting messages and are opting out of having their children vaccinated.
And that means diseases like measles are starting to appear again.
An outbreak has already taken hold in Ireland, where two babies died, more than 300 children were infected and 100 needed hospital treatment for measles.
Dr Peter Keenan, from Temple Street Children's Hospital in Dublin, told the BBC: 'I have not seen measles here since I was here as a registrar in the late '70s.'
Experts blame the outbreak on Dublin's MMR vaccination rate of just 70 per cent.
Microbiologist, Dr Mary Cafferky, said: 'It is appalling, it is preventable, it should not be happening.
'People have forgotten that measles is a severe multi-system illness - that is why the vaccine was developed.'
And experts in the UK fear the same thing could happen in Britain - possibly from the start of next year or the year after, unless parents ensure their children are vaccinated.