The festering row over the controversial MMR jab this morning engulfed Downing Street, the Department of Health, the Conservative party and even the Sun newspaper, as small outbreaks of measles continued to spread across the country.
Dr Liam Fox, the shadow health secretary, finally broke the bipartisan approach to the combined measles, mumps and rubella innoculation, calling on separate jabs to be available on the NHS.
Meanwhile, No 10 partially denied a front page claim in today's Sun that the prime minister had ordered a review of the comparative costs of the individual injections - available in private health clinics at about £60 each - following measles cases in south London and Gateshead.
Dr Fox said: "In the circumstances, I think that reluctantly we have to accept that single jabs may be the only way of giving children protection.
"The important thing is that public confidence has fallen to a level, rightly or wrongly, where children are unnecessarily being put at risk.
Dr Fox added: "It is not acceptable to stand back and say we are going to give you MMR or nothing at all, because the nothing at all could lead to a lot of children being damaged."
Despite a Tory claim that they were still backing the MMR jab in principle, and wanted it better advertised, the Dr Fox's new position caused a howl of protest from the Department of Health and the Liberal Democrats.
The government's deputy chief medical officer today insisted that MMR was "the most researched vaccine ever" and said there were no plans to introduce single jabs.
Dr Patricia Troop said the new research linking the virus to autism did not appear to be significant to the vaccine programme.
"Nobody has asked me to look into the price of single vaccines," she said.
"It is used in 90 countries in the world, 500 million children have used it, it has a terrific record. The situation would be worse, not better, if we had single vaccines," she said.
The Sun's political editor, Trevor Kavanagh, stood by his story that Downing Street was reviewing the MMR issue.
Mr Kavanagh told BBC Radio 4's Today programme: "Whatever the Department of Health and Downing Street say, I know that the prime minister is deeply concerned about the outbreak of measles in various parts of the country, about the impact of his decision not to reveal his son Leo's innoculation plans, and the effect of concern over possible autism side effects from the MMR vaccine.
"What I do know also is that he has asked for a summary of the costs, a comparison between the cost of the MMR triple jab and the individual cost of separate innoculations."
Public health minister Yvette Cooper, however, insisted: "This story is not true. We have never made costs a consideration in this issue.
"We have always done this on the basis of what is best for the children, and what is recommended by the medical experts."
Asked whether she was ruling out a review of MMR, Ms Cooper said: "The independent experts that advise us, and the medical experts that advise us, continually reassess the evidence and look at all the new evidence, and their advice has not changed, so our position has not changed."
She added: "All the new evidence that has come up has been reviewed at every stage along the way and it has all shown that there is no link between MMR and autism and that MMR is the safest way to protect children and that introducing separate jabs would put more children at risk."
Ms Cooper attacked the Tory position, saying: "It is the easy political option to jump on the bandwagon here as the Tories are doing and call for separate jabs. "I think it is opportunistic and I think it is undermining parents' confidence."
On her own two young children, Ms Cooper said: "I have made my position clear for a long time on this, that my children do have all the jabs that they are recommended."
The Liberal Democrat health spokesman, Dr Evan Harris, accused the Tories of "playing politics with public health".
He said: "It is the height of irresponsibility for the Tory spokesman to call for the provision of what he accepts is a less effective and less safe approach.
The government immunisation programme aims to give the MMR jab to 95% of children, but levels have fallen to 65% in London, where three cases of measles were confirmed last week.
Results of tests were today expected on another 22 suspected cases, and four cases have been detected in the Gateshead and South Tyneside area, which has a 91.4% immunisation rate.
Public Health Laboratory Service figures show that UK-wide take-up of the MMR jab plummeted to a record low between July and September last year, with a coverage rate of just 84.2%.
MMR coverage in the Lambeth, Southwark and Lewisham areas of London, where the first three cases were confirmed, hit just 72.3% in one quarterly period.
A Department of Health spokesman said that any rate below 95% did not give "herd immunity".
He said: "This means it is not just children who have not had the jab who are at risk, but those below the age at which it is given.
"It is important that health authorities should encourage people to take up MMR, which is the safest way of protecting against these diseases."
The Times reported today that some children who caught measles in the outbreak in Streatham, south London, had already had an MMR vaccination.
The health authority for Lambeth, Southwark and Lewisham said that the suspected cases did include those who had the MMR vaccine but not the booster, the paper said.
The first MMR vaccine, administered between 12 and 15 months, is supposed to give 92% protection against measles and the booster, given before the age of five, another 7%.
Some 2,000 families in Britain have taken legal action, claiming their children have been damaged by the jab.
The prime minister has stoked the row by refusing to answer Tory questions over whether Leo Blair, who is 18 moths old, has had the MMR jab.
Mr Blair said it was an invasion of privacy - prompting speculation that the intensely health-conscious Cherie Blair had rejected the combined innoculation. The prime minister later backtracked into saying that any assumption that he would reject official government advice over the jab was extremely hurtful - but still refused to give a straight yes or no answer.
