ÐÓ°ÉÔ­´´

THE rate of new cases has slowed to a trickle but Britain’s foot and mouth
epidemic is not over yet. This despite the fact that 4 million animals have been
slaughtered in what is easily the largest and most costly outbreak of the virus
the modern world has seen. And with winter bringing the cold, moist conditions
the virus likes, things could get worse again. Surely the outbreak should have
been over by now if the government’s strategy for controlling it had been
sound?

In fact, two of the most detailed attempts so far to discover what would have
happened if the strategy had been different suggest the official approach was
about right. Published in high-profile journals (Nature and
Science), the computer simulations conclude that there really was no
alternative to slaughtering all those animals. Indeed, the problem was that the
killing wasn’t done quickly and ruthlessly enough. If the slaughter teams had
been mobilised without delay and had succeeded in meeting the target of killing
all at-risk animals in and around infected farms within 48 hours, the epidemic
would have been halved.

In contrast, vaccination comes out very badly. Inoculating animals on
neighbouring farms instead of slaughtering them would have led to 8 times as
many cases, while vaccinating and killing would have cut cases by just 20 per
cent. Not very impressive. Worse, since vaccinated animals can continue to carry
tiny amounts of live virus for months, most of those given jabs would eventually
have had to be slaughtered too.

So does that settle the debate about vaccination? Not a bit of it. For one
thing, the scientists behind the computer models were largely those who advised
the government to make slaughter, not vaccination, the linchpin of its control
strategy in the first place. What’s more, the models tested just one vaccination
scenario without revealing how the picture would change if the vaccinations were
carried out more quickly or more widely. As a result, we still do not know
whether swift and aggressive vaccination combined with slaughter would have
snuffed out the epidemic earlier. We might guess that it would have caused acute
suffering in areas hit early in the epidemic, while perhaps saving animals
across the country as a whole. And perhaps vaccination would have eased concerns
about the virus spreading from farm to farm, enabling footpaths to open sooner
and limiting the damage to the wider rural economy, most of which doesn’t depend
on farming. But modelling hasn’t yet given us definitive answers.

Nor has it pinned down the general circumstances in which vaccination can
help a country deal with an outbreak. No two outbreaks are the same. Britain
shunned vaccination this time round. But that doesn’t necessarily mean it would
be wise to do so next time.