Would single vaccines have improved protection in the population?

OK, no jokes or satire this time. Just a cold hard look at this one remaining issue.

From the beginning, my main point was that irresponsible journalism bears a great deal of blame for the current crisis (now threatening to spread to Birmingham). This point has been made again very eloquently (sorry this is behind the Times Paywall) by my comrade in arms (on this topic) journalist David Aaronovitch. He focuses especially on the South Wales measles outbreak, MMR uptake in that area, and misleading coverage provided by the South Wales Evening Post; but he has harsh words for many journalists - including journalists at the BBC (to wit a letter of complaint to them from me and their shameful response).

Many journalists have, meanwhile, offered their mea culpas but (as anyone who has been following my blog will be aware) the journalist Peter Hitchens has argued strongly that fault lies not with journalist like him who ran stories suggesting there might be some substance to fears about MMR (there isn't by the way) but with the NHS which, in spite of those fears, refused to provide courses of six single vaccines as an alternative to the two MMR (measles, mumps, rubella) combined jabs.

In my first post on this topic I set out briefly what the problem was with the NHS offering single vaccines, and Martin Robbins, writing in the Guardian, has gone into a great deal more detail on this topic. Mr Hitchens remains unconvinced:

@schroedinger99 @mjrobbins ...should be available for those who want them.Once again YOUR POLICY FAILED.

— Peter Hitchens (@ClarkeMicah) May 1, 2013

This graph (from the BBC) shows MMR uptake rates since 1997 (this vaccine was introduced in 1988 and replaced single measles and rubella vaccines - there never was a licensed single mumps vaccine in the UK):



It seems obvious to Mr Hitchens (and his supporters) that, had we offered single vaccine programmes once the unfounded autism scare had taken hold, this would have ensured that the missing yellow in this graph would have been filled in as parents who had eschewed MMR switched to single vaccine programmes instead.

Now, as has been argued, there are all sorts of reasons - logistical, financial, and ethical - why the NHS did not give in to various pressure groups and provide the less well tested single vaccines. And we are not alone. No other country in the world has a national six jab single vaccine programme. Let us, however, suppose that all these objections had been overcome and we had managed to secure huge supplies of single vaccines with a reasonable (though less than fully documented) safety record. Would it have worked?

The graphic below illustrates the MMR only regime and Peter Hitchens's proposal (which was also Andrew Wakefield's proposal) side by side.[1]



Now what Hitchens and like minded people seemingly fail to grasp is that the NHS provision of a single vaccine programme and (especially) the announcement of said in the media would have resulted, not just in the transfer of people from the no vaccine group to the singles group but also a huge transfer of people from the MMR group to the singles group.

If single vaccines were just as good as MMR, this wouldn't matter. But there are three relevant problems with single vaccines (in order of increasing significance):

1. The immune reaction they produce is not quite as strong. Less than one percent of kids who get both MMR jabs will still lack immunity. With single vaccines the percentage is higher (exactly how much higher is difficult to say with confidence since there are a number of different preparations and far less data on the use of six single vaccines rather than two MMR vaccines)
2. Andrew Wakefield suggested a one year gap between jabs. If this protocol were followed, kids receiving their first jabs would have to wait two more years before they stood any chance of being fully covered and a further three years to achieve maximum protection.
3. Compliance with six single vaccines would be much lower than compliance with two MMR jabs. People move house, have fallible memories, decide not to bother, lose paperwork, miss appointments etc. - especially when they are not paying for the vaccines themselves.

(There are also the - admittedly statistically small but still significant if they happen to you - problems of increased dangers of allergic reactions, infection and injury from the injections themselves - if you have six rather than two - but let's just concentrate on the numbers aspect.)

If we assume, for the sake of argument, that the average single vaccines child will be (because of the considerations listed) fifty-percent as well protected as an MMR child, then the benefits of any transfer from the No Vaccines group to the Singles group in the above diagram will be wiped out by the same number of transfers from the MMR group to the Singles group.

If we assume that the average single vaccines child will be thirty-three-percent as well protected as an MMR child, then the benefits of any transfer from the No Vaccines group to the Singles group in the above diagram will be wiped out by the half the number of transfers from the MMR group to the Singles group.

If we assume that the average single vaccines child will be sixty-seven-percent as well protected as an MMR child, then the benefits of any transfer from the No Vaccines group to the Singles group in the above diagram will be wiped out by the double the number of transfers from the MMR group to the Singles group.

There are three variables here: 1) the transfers from the No Vaccines group to the Singles group 2) the transfers from the MMR group to the Singles group; and 3) the percentage cover provided to the typical recipient by a programme of single vaccines.

Nobody, and certainly not Peter Hitchens, knows for certain what these three variables are, but we can make educated estimates. Apart from any other considerations, the fact that the MMR group is very large in relation to the other two groups tells us that even a small percentage of switchers from this group would have resulted in very large absolute numbers of switchers.

But, and here's the clincher, even if you are quite convinced (as I'm sure Mr Hitchens is despite expert opinion) that that the benefits would have outweighed the drawbacks had we introduced single vaccines back in (say) 2004 (or prior to then), just look at what has happened to MMR uptake rates since then!

Had we supplied single vaccines back in the day, this would not just have been for one year. We'd have been stuck with them forever. And every year that has passed since 2004 would have made the statistics (for MMR plus single vaccines provision) worse in comparison to MMR alone. We are now (thank goodness) nearly back up to the levels of MMR uptake we had before the scare. Any transfers to single vaccines beyond this point would reduce immunity in the population - even if single vaccines were ninety-ninety percent as good as MMR (which they certainly are not).

It is highly unlikely that single vaccines would have improved matters, even in 2004. Even if it would have done, It is virtually certain that, over the course of time, the cumulative effect of the option illustrated on the right of my diagram would have been worse overall than sticking with MMR only. The NHS did absolutely the right thing.

Of course the only reason we are having this discussion is because there was a scare. Instead of informing themselves and reporting responsibly, journalists in the print and electronic media blithely spread the scare around. Those journalists, I'm afraid, need to examine their consciences if any death or disablement results from the current outbreak. They did not do the right thing.





[1] I've simplified things by assuming that those using single vaccines privately under the current regime would have continued to do so or would have switched to NHS provided single vaccines under the alternative regime. This would have had no overall effect and can be ignored. I've also simplified things with respect to the fact that some MMR recipients fail to get the second MMR jab. The numbers, in this case, would be slightly different on either side of the equation but, since the numbers getting MMR are high and the numbers on getting the second jab are low, this would make very little difference and this complication can be ignored.

PS It occurs to be that this post may come across as journalist-bashing. I should perhaps emphasize that there are one or two scientists who don't come out of this smelling of roses and that it is only due to the tenacity of a journalist - Brian Deer - that the full story of Andrew Wakefield's actions ever came to light. (Life is complicated and simplistic explanations are usually wrong!)