I have avoided writing about flu shots because, as you will see, it was not in my best interest to do so. But now that Alex has let the cat out of the bag, I might as well share my thoughts.

All along the hippies said “vaccinations are dangerous” and the doctors said “nonsense, you don’t understand science”. Then in 1976 they noted that Guillain-Barré syndrome is a possible side-effect. And in 1999 they removed (mercury-based) thiomersal “just in case” it causes autism. Next up, dystonia. This irony should be humbling to epidemiologists.

We think of modern medicine as being evidence-based, but this is a new, unevenly applied paradigm. Pure evidence-based medicine eliminates theories. For example, influenza virii might cause the flu and be prevented by inactivated vaccinations, but all that science says is that people injected with this stuff don’t get sick. Evidence-based doctors do not infer treatments from their clinical experience: evidence-based medical students don’t do internships.

We can only say that public health is evidence-based, not evidence-bound. Studies have uneven burdens of proof and many results don’t hold up under rigorous review. Doctors need to stop labelling their critics as “unscientific” and start appealing to the inform reasoning they secretly use themselves.

Yes, it is worse to die from Guillain-Barré syndrome than the flu. But your chance of dying from the flu is so much higher that most people should choose a vaccination. And please be a good citizen and forget the fact that if everyone else is immune to the flu then you don’t need to be.