Public health policy aims to protect society from disease - sometimes, at an individual's expense. One person in 2.4 million inoculated with the polio vaccine gets the disease. Before the vaccines were introduced in the US in the 1950s, however, the virus afflicted tens of thousands each year, so the public wins, despite that minuscule individual risk. Growing numbers of malcontents, the "anti-vax" campaigners, allied increasingly with the Tea Party movement in the US, detest their government's directives on vaccination.
The effect can be seen in the fallout from the scare over the MMR (measles, mumps and rubella) single jab. Where 95 per cent of the population is vaccinated, the probability of the measles virus finding a body in which to propagate diminishes; and so measles eventually disappears. When the MMR jab was (falsely) linked to autism, however, UK vaccination rates dropped and so measles is on the rise. Non-immunised people keep the germs in circulation.
It's not just anti-vax individuals at risk. Newborns, for instance, aren't immunologically ready to take the vaccine - they rely on not coming into contact with the disease. Tea Party activists, therefore, face a dilemma. Can one pursue a pro-life crusade for the unborn while also defending the right of the unvaccinated to endanger babies?