Herd instinct

by Mark Broatch / 29 January, 2015
Photo/Getty Images

When Eula Biss became a mother, she began to investigate immunisation and found among many parents an ecology of fear – of vaccines, of doctors, of government – and a serious misunderstanding of risk.

The term “conscientious objector” originally referred to those who refused vaccination. Anti-vaccination advocates often frame the debate in terms of individual liberty and the integrity of science. But vaccination also enlists the majority in the protection of a vulnerable minority – newborns, the elderly, pregnant women – doesn’t it?

Yes, this is why the term “conscientious objector” caught my interest. The question of whether or not to vaccinate one’s child strikes me as a question of conscience, in part because the mechanism of mass vaccination sometimes depends on people who may not be the most vulnerable to a disease submitting their bodies to vaccination in order to protect the most vulnerable. Rubella is a good example – the majority of people, including infants, are unlikely to suffer major complications from rubella. But unborn babies are uniquely vulnerable to rubella, and when pregnant women are exposed to the disease they are much more likely to give birth to babies with major birth defects, including mental retardation. Before the vaccine against rubella, about 20,000 babies were born in the US every year with major birth defects due to congenital rubella syndrome. So rubella is very dangerous to unborn babies and we protect them against it by essentially taking the disease out of circulation (through mass vaccination) so that pregnant women are unlikely to be exposed. When we vaccinate an infant against rubella, we are not doing it to protect that infant, but to protect infants who have yet to be born. The vaccinated child has already benefited from herd immunity to rubella and is, in a sense, paying back into the system by accepting a vaccination that will protect other babies.

Early vaccination held dangers, didn’t it? How safe is immunisation now compared with not getting the jab?

Vaccination circa 1850 was quite dangerous by our standards, but not as dangerous as smallpox, which had a 30% mortality rate. At that time, smallpox vaccination was often practised “arm-to-arm”, meaning that a pustule on a vaccinated person’s arm was opened and the pus was used to vaccinate another person. The exchange of bodily fluids meant that vaccination could communicate a number of diseases, including syphilis. But the smallpox vaccine, even after it was modernised, also had a relatively high rate of serious side effects. It frequently caused fevers and rashes, and about one in every million people vaccinated against smallpox would die from a reaction to the vaccine. Nearly everyone in my parents’ generation was vaccinated against smallpox and took that risk, but my generation has enjoyed the good fortune of being born after the eradication of smallpox.

Eula Biss

None of the vaccines my son has received are as dangerous as the smallpox vaccine, but none of them are without risk. And that’s true, of course, of most things in life – very few things worth doing hold zero risk. The question of how safe immunisation might be compared with not getting the jab is a deceptively complicated question. It is possible to calculate the risks of not being immunised if we assume the current rates of immunisation, but as soon as those rates begin to fall, the risk of not being immunised increases. At the moment, the risk of suffering a serious reaction to vaccination is very low, as is the risk, in many places, of contracting a dangerous infectious disease. The numbers in the US are tiny for both, though the incidence of serious vaccine side effects is still lower than the incidence of serious complications from infectious disease. So, the short answer is that immunisation remains safer than disease.

We fear mercury, formaldehyde and aluminium as causes of autism, immune dysfunction, MS, cancer or poisoning. What’s the reality of these fears?

The results of decades of scientific study do not support these fears. We may occasionally see someone trot out an outdated or discredited study to justify one of these fears, but when the research is considered as a whole, rather than cherry-picked, it is really quite reassuring. The research on autism has been particularly extensive and there is a rare degree of consensus in the scientific community that autism is not caused by vaccination.

And we frequently misunderstand risk – we fear sharks but mosquitoes are possibly the most dangerous creature on Earth, you write.

Yes, mosquitoes are far more deadly than sharks. And most people are fairly bad at gauging risk. I’m fascinated by Paul Slovic’s research on risk perception, which was among the more surprising and interesting subjects I stumbled onto while writing On Immunity. Slovic’s studies reveal, again and again, that people do not tend to be most afraid of the things that are most likely to harm them. We often prefer to be afraid of things that capture our imaginations and excite existing prejudices. After reading quite a bit of Slovic’s work, I began thinking about the risks I accept in my life and the risks I take for granted. I realised that I am willing to accept a fairly high degree of risk – the risk of carrying my son on the back of my bicycle in traffic, for instance – when that risk is convenient, practical and supports something that I value, like exercise in the open air. On reflection, I had to admit to myself that vaccination not only is far less dangerous than commuting by bicycle or automobile, but also supports some of my most fundamental values, like contributing to the well-being of my fellow citizens.

ON IMMUNITY: AN INOCULATION, by Eula Biss (Text Publishing, $37).

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