One million schoolchildren in England who missed MMR jabs are to be targeted by a vaccination plan aimed at curbing the growing threat of measles.

Health officials warn epidemics similar to the one in Swansea, which has seen nearly 942 cases, could occur anywhere.

There are fears that a generation of children have low levels of protection after the MMR scare a decade ago.

The catch-up campaign, run through GPs, schools and community groups, will focus on children aged 10 to 16.

The campaign is expected to cost £20m and the Department of Health already has 1.2 million vaccines ready to go.

It will aim to vaccinate children yet to be protected with the MMR - measles, mumps and rubella - jab by September.

Measles is a highly contagious disease characterised by a high fever and a rash. In one in 15 cases it can lead to severe complications, such as pneumonia and inflammation of the brain, and can be fatal.

In 2012, there were nearly 2,000 cases of measles in England - the highest figure for nearly two decades.

This year could be another record with cases already higher than at the same point last year.

Discredited research

Children aged between 10 and 16 are the most likely to have missed jabs when research linked MMR with autism and caused vaccination rates to plummet. The research has since been discredited.

The most urgent need for vaccination is in the third-of-a-million completely unprotected children in that age group. They should be given their first MMR jab before the next school year and a booster jab later.

A similar number of children who had only their first MMR vaccine will be targeted with their booster.

The aim is to give a further third-of-a-million children in other age groups, who are not totally protected, their vaccines as well.

Prof David Salisbury, the director of immunisation at the Department of Health, said parents needed to act to prevent outbreaks on their doorstep.

"Swansea is the wake-up call for parents and it tells us just how infectious measles is - it just spreads like wildfire.

"If you think your child has not had one or even two doses of MMR, for goodness' sake contact your GP and get it sorted out.

"The message from Swansea is very clear and it is trivialised at the risk of your children's health."

Similar plans are already under way in Wales.

Both Scotland and Northern Ireland maintained relatively high MMR uptake but NHS boards in Scotland are to write to parents of all unvaccinated or partially vaccinated children aged 10 to 17 with an invitation to attend for vaccination over the next few weeks.

Danger zones

Figures from Public Health England show there have been 587 confirmed cases of measles in the first three months of 2013.

A fifth of cases needed hospital treatment and 15 people developed complications such as pneumonia, meningitis and gastroenteritis.

The cases were mostly in the north-east and north-west of England, even though the north of the country generally maintained high levels of vaccination at the height of the MMR scare.

Dr Mary Ramsay, head of immunisation at Public Health England, said: "We have potential for school outbreaks in many areas of the country.

"The areas most likely to be affected would be London and the south and east of the country, where we know that the historical coverage was not as high."

Prof Salisbury said he worried about London because of the high density of people, who were rapidly moving.

He warned that children who received single jabs, instead of the combined MMR, may also need additional protection as there had been "major problems" with the quality and storage of some of the vaccines handed out.

He added that nobody should be considering single jabs now.

Dr Paul Cosford, the director for health protection at Public Health England, said: "Although nationally the numbers needing catch-up vaccination is quite large, there are relatively few in each local area.

"We are confident that local teams have the resources to identify and vaccinate those children most at risk."