Public health authorities have confirmed that England aims to inject a million youngsters with measles vaccine following a surge in cases of the potentially fatal disease.
The rise in cases appears to be due to a period in the late 1990s and early 2000s when fears over a discredited link between the MMR vaccine and autism were at their height, Public Health England (PHE) said.
The MMR vaccine immunises against measles, mumps and rubella.
It comes amid an outbreak in neighbouring Wales, centred around the south coast city of Swansea, where the number of people who have contracted the disease between November and April now stands at 886.
In London, Health Secretary Jeremy Hunt said it was time to "slay the myth" about the injection, which dates back to discredited research published in 1998 claiming a link between autism and the jab.
The new £20-million ($30-million, 23-million-euro) campaign in England aims to reach a million people, with the priority on the estimated third of a million youngsters aged 10 to 16 -- around eight percent -- who are completely unvaccinated.
The further estimated third of a million who need further MMR jabs for full protection come next, with the remaining third of a million youngsters above and below the age group who need vaccinating.
Speaking to parliament's health scrutiny committee, Hunt said Wednesday: "We need to use this as a moment to slay the myth about MMR and I do detect a turning point in terms of the public's attitudes towards this."
"But there is still that critical 11 to 15-year-old age group that may not have been vaccinated because they were toddlers at precisely the time when the MMR scare was so appallingly whipped up."
"I want to reassure you, we are taking this extremely seriously."
Experts believe the rise in measles cases can be mostly attributed to the proportion of unprotected 10 to 16 year olds who missed out on vaccination in the late 1990s and early 2000s when concern around the vaccine was widespread, according to the PHE.
At this time measles had been eliminated in Britain, but coverage fell nationally to less than 80 percent in 2005, with even lower uptake in some parts of the kingdom.
After many years of low vaccination uptake, measles became re-established in 2007.
"Measles is a potentially fatal but entirely preventable disease so we are very disappointed that measles cases have recently increased in England," said PHE immunisation head Mary Ramsay.
"Those who have not been vaccinated should urgently seek at least one dose of MMR vaccination which will give them 95 per cent protection against measles. A second dose is then needed to provide almost complete protection."
According to the latest World Health Organization figures, 158,000 people, the majority of them young children, died in 2011 worldwide from the virus.
The figure has dropped 71 percent since 2000, when 548,000 deaths were recorded.