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IN THE face of fading public confidence, the British government is fighting
tooth and nail to restore faith in the MMR vaccine against measles, mumps and
rubella. But is it a fight that the government can win?

The crisis stems from a controversial claim in 1998 by gastroenterologist
Andrew Wakefield that MMR may trigger autism and bowel disease in a few
children. Clear evidence for or against this idea is proving hard to come by
(see “A stab at the truth”).
And if there is a risk, it will affect
far fewer children than those ravaged by measles without the vaccine. But the
uncertainty has led increasing numbers of parents in Britain to refuse to have
their children vaccinated with MMR. The proportion receiving their initial shot
has dropped from 88 per cent in 2000 to about 84 per cent now. If uptake falls
below 80 per cent, the country could be plunged into a major measles
epidemic.

Last week the government’s chief medical officer, Liam Donaldson, outlined
the reasons against offering the option of “single vaccines”—separate
vaccinations against each disease. Each vaccine requires an initial shot and a
booster, so children would have to have six shots instead of two. Parents might
fail to show for all the shots, or lose confidence in vaccinations altogether.
“Uptake rates would fall,” says Donaldson, leaving more children susceptible to
the diseases and opening the door to epidemics. It would, he says, be like
playing “Russian roulette” with children’s health.

But is this stance justified? In arguing for it, the government has leaned
heavily on the few past examples of governments changing their vaccination
policy. Unfortunately, the comparisons are questionable.

Last week Tony Blair cautioned that 85 Japanese children died of measles in
the five years after 1993, when Japan became the only country to switch from MMR
to separate vaccines. Their problem with MMR was different—the mumps
component, which is different from Britain’s, caused meningitis. But using a
separate measles vaccine, Japan now reports the same coverage for measles as the
US—an enviable 96 per cent. Contrary to British fears, abandoning MMR was
followed by better compliance.

And in the US, the percentage of children vaccinated for measles remained
stubbornly in the low 60s between 1970 and 1985, despite the introduction of MMR
in 1975. A mass-education campaign increased the coverage, rather than a change
in vaccine.

The government is also relying on another British vaccine scare to show that
single vaccinations can hurt uptake. In the 1970s there was a catastrophic loss
of public confidence in the combined vaccine against whooping cough, tetanus and
diphtheria, following research that suggested the whooping cough component could
lead to brain damage. After coverage dropped to half, the government capitulated
and offered a single whooping cough vaccine. Donaldson insists the move was a
poor one. “The uptake rate fell to 30 per cent, it took 15 years to recover, a
quarter of a million children developed whooping cough,” he says. But no one
knows if it would have been better to switch sooner rather than not at all, or
whether vaccination rates would have fallen further without the change in
policy. Uptake rates under the single vaccine began to rise before the combined
vaccine was proven safe in the 1980s.

Measles in Britain still seems to be under control. There have been 268
reported cases this year, compared to 258 over the same period in 2001. And it’s
not even clear by how much the overall rate for measles vaccination is falling.
Data on coverage from the single vaccines is scant, as some doctors don’t seem
to be reporting their single vaccinations and some parents are taking their
children abroad for separate shots.

The Public Health Laboratory Service says there has been a steady decline in
children being vaccinated with MMR before they are 16 months old
(see Graph).
But it’s not known whether this is because parents are abstaining from all
vaccines, switching to single vaccines, or simply delaying vaccinations while
they make up their minds.

The government fears those delays will become even longer if they allow the
public to choose single vaccinations instead of MMR. That fear is based mainly
on Wakefield’s suggestion that the separate vaccines should be given a year
apart in order to avoid “overloading” children’s immune systems. That long delay
would indeed leave children unprotected in between their shots.

But there is no research to show that a year’s gap is necessary, or if
overload is even a problem. So some researchers suggest the best way to stem
fears of overload is to offer separate shots at one or two-month intervals from
a child’s first birthday instead. This could ensure that children were covered
by the time they were 16 months old.

Ironically, the argument about when single vaccines should be given may prove
irrelevant. There is no reason to believe that an overloaded immune system is
the most likely culprit for potential problems with the vaccine. Some
researchers believe that the problem may lie in the measles virus itself for a
few children who have a genetic susceptibility to bowel and developmental
problems. That means the problems would continue regardless of whether children
are exposed to measles from natural sources, the MMR vaccine, or the single
jabs. “Based on what I’m seeing, there’s a very inappropriate reaction to
measles [in these children],” says Vijendra Singh, a neuroimmunologist at Utah
State University in Logan. “Even if you have a single measles vaccine, the
culprit may still exist.”