Preaching to the unconverted: immunisation risks and public health

Late 19th century lithograph by French artist Gaston Mélingue showing Edward Jenner vaccinating a boy on May 14, 1796. Wikimedia Commons

The principle of prevention being better than the cure is at the heart of public health and social marketing efforts such as immunisation. But not everyone agrees and the challenge is how to address disagreement.

What I am about to say will almost certainly provoke ire, but here it is: immunisation can be dangerous to your health.

This truth is acknowledged in the Australian Academy of Science’s recent publication, The Science of Immunisation: Questions and Answers. Admittedly, the risks are small, maybe even “extremely small” as they state. But like many medications, there are risks – even if they’re written in small print.

But while in medical practice, the individual gets to read about the side effects and choose whether or not to take a drug or some other kind of therapy, in public health, this same option is not offered to that individual.

And as one might expect, public health agencies tend to emphasise the benefits and discount the risks. The Science of Immunisation report, for instance, tells us that “all vaccines in use in Australia provide benefits that greatly outweigh their risks”.

For personal medications, we choose for ourselves. But who makes the decision about what is good for us in public health? How do they make this decision? And why should we believe them?

Indeed, these questions are the heart of an important issue that confronts all public health and social marketing efforts. And it’s neatly crystallised in the debate about immunisation which has been going on for around 300 years.

In the 1720s, the inoculation of English children with powdered scabs from smallpox sores to prevent later infection by smallpox was promoted. Smallpox was undoubtedly a dangerous disease killing up to a third of those infected. But inoculation could also be dangerous, leading to the deaths of up to 2%.

Then, as now, the key question for individuals was whether or not to immunise.

Voltaire famously characterised the balancing of risks in his Lettres Philosophiques

[Europeans consider] the English are fools and madmen. Fools, because they give their children the small-pox to prevent their catching it; and madmen, because they wantonly communicate a certain and dreadful distemper to their children, merely to prevent an uncertain evil. The English, on the other side, call the rest of the Europeans cowardly and unnatural. Cowardly, because they are afraid of putting their children to a little pain; unnatural, because they expose them to die one time or other of the small-pox.

Then Edward Jenner invented the original vaccine, inoculating his patients with cowpox to prevent infection by smallpox. His findings were mocked publically by religious and scientific authorities.

Today, scientific authorities and public health interests argue that the benefits of immunisation far outweigh the pain of the few who may suffer from vaccination. And from a public health point of view, they are correct.

So why then do people refuse to immunise? Why are so many people reluctant to vaccinate?

Unfortunately for public health agencies, people are notoriously bad at estimating risks and probabilities. Few, if any, read meta-analyses or systematic reviews, and many are very bad at understanding science and statistics.

So just as some people in the 18th century believed that Jenner’s original vaccination might give rise to cows growing out of the body and was against God, today some people believe that the MMR (measles, mumps, rubella) vaccination can give rise to autism.

But despite their misguided beliefs, they have some reason on their side that ought to be acknowledged, even if only to better guide public health programs.

The first is that there are some risks associated with immunisation. Maybe not the risks identified by the anti-vaccinators, but risks nonetheless. Second, and perhaps more importantly, the public health agenda asks individuals to sacrifice their rights to the greater good. Is this just?

Perhaps it helps to make this personal. If you or your child suffered the rare adverse reaction to a vaccine, is it fair that you bear this burden for the greater good?

Public health practitioners have to act pragmatically but promotion efforts are likely better guided by a realistic view of the intended audience. And such practical matters shouldn’t prevent scientists, philosophers and academics continuing to debate these important issues.