I wonder whether the latest twist in the MMR saga will have any impact on vaccination rates. To most people, I suspect, the claims and counter-claims about conflicts of interest and research ethics will seem utterly irrelevant to the fundamental question of whether MMR is safe.

Dr Andrew Wakefield, the researcher who sparked the MMR scare, was accused of concealing a conflict of interest by failing to disclose his work for the Legal Aid Board. The Lancet has declared his study "fatally flawed", and said it would never have been published had it known he was paid £55,000 for his research fund by the Board to help prepare a case against the vaccine manufacturers.

The discovery was made by The Sunday Times's reporter Brian Deer, who had apparently spent four months investigating the matter. Which was funny, given that Dr Wakefield himself disclosed his links with the Board in a letter published in The Lancet in May 1998, three months after his study had appeared.

Now there are dark rumours of a Government conspiracy, with allegations that someone with an interest in undermining Dr Wakefield must have tipped off Mr Deer about the legal aid link. I don't know if this is true, but it does seem odd, given the trouble Dr Wakefield's paper has caused to the national vaccination programme, that it has taken six years for the facts to come out. There must be a number of people on the Board who might have noted the conflict of interest, and pointed it out to the health department.

On the other hand, I can think of few reporters less inclined to accept a brief from a Government stooge than Mr Deer. I remember leaving a Department of Health Christmas party with him more than a decade ago, and as we walked down the corridor he suddenly dived into an empty office, yanked open a filing cabinet and began rifling through its contents in search of some juicy Government memo. Upsetting applecarts is what drives Mr Deer, and his past scoops have won him awards as Journalist of the Year.

Dr Wakefield, who commutes between the UK and the US since leaving the Royal Free Hospital in 2001, is said by those who know him to be badly shaken by the latest round of publicity, rarely venturing out of his home. He has become increasingly anxious, believing that his phone is bugged and that there is an orchestrated campaign against him, according to his friends.

None of this will alter the view of parents convinced that MMR is damaging. Indeed it may reinforce their view that there is a Government conspiracy to promote MMR - a belief that ministers and officials worry about encouraging. Evidence shows that any publicity about MMR - even that which, as in the last week, undermines the credibility of the author of the scare - tends to deter more people from vaccination than it encourages.

One thing that puzzles me is why sensible people who reject MMR on safety grounds are nevertheless happy to accept single vaccines, without checking their safety record.

We know a great deal about the safety of MMR because more than 500 million doses have been used around the world since 1970. None of the single vaccines has a safety record that comes close to matching that.

It reminds me of the arguments we had in my household at the time of the BSE scare in the mid 1990s. Like many others, we struck beef from the menu when Stephen Dorrell, the then Secretary of State for Health, told a shocked House of Commons that a new disease, variant CJD, had appeared in humans, linked with BSE in cattle.

I was against removing beef from the menu because cows with BSE had been excluded from the food chain since the late 1980s - so we were shutting the stable door long after the prion (the agent that causes vCJD) had bolted.

But more important was what was replacing the missing beef. In our case it was lamb, which contains about five times as much fat. Thus by excluding one theoretical risk, of getting vCJD, we were embracing a greater known risk of developing heart disease. Luckily, beef has long since been re-established on the household shopping list.

We cannot avoid risks, we can only exchange them. Melanie Phillips complained in the Daily Mail last week that MMR could not be said to be safe, and the most that could be claimed is that there was no evidence that it was not safe.

But this is a truism. If "safe" is defined as "free of risk" then nothing can be said to be safe. Every human activity carries some risk. Safe means "negligible risk", and on that definition MMR is safe.

Parents who opt for single vaccines for their children are like those who switched from rail to road after the Potters Bar train crash. With headlines screaming about the decline of the railways, it may feel safer behind the wheel, but it ain't.