First she says that we still don't know 'what exactly causes autism'. This is true only to a point. Autism is strongly genetic in origin; a recent study found that if you have one child with an autism spectrum disorder (ASD) you have an 18 per cent chance of having another, a much higher figure than previously thought. Researchers have also identified a number of risk factors: older mothers, older fathers, birth complications, low-birth weight babies and twins, all factors that point to ASDs developing in utero, even though symptoms may not become apparent until many months after birth. And yes, scientists are looking closely at environmental contributors such as pesticides and infections in pregnant mothers. Vaccines are only one environmental factor under investigation but are by far the best studied. When, several years ago, concerns were first raised that childhood vaccinations may be linked to autism the mainstream medical community took these worries seriously and conducted study after study around the world: these were consistent in their outcomes: no link, no link, no link, no link. Ms Lefroy then brings up the case of a young girl with a rare genetic mitochondrial disorder who received a substantial payout under the US National Vaccine Injury Compensation Program when she developed an encephalopathy with 'features of autism'—not 'autism' as Ms Lefroy claims—after receiving several vaccines. (Encephalopathy is an extremely rare but recognised side effect of some vaccines. That's why the US government didn't contest the case.) What she doesn't mention was that this case was originally part of the much larger Omnibus Autism trial, a class action representing almost 5000—yes 5000—cases brought by families who claimed their child had developed autism from vaccines. And what happened to the other 5000 or so cases? After hearing months of testimony and reviewing mountains of evidence on the test claims, the independent Special Masters of the Vaccine Court dismissed them; in fact they were scathing in their judgements of the lawyers who pursued the action based on such flimsy evidence. 'Not even close', was one judgement. Thirdly Ms Lefroy quotes an interview with Dr David Amaral, from the University of California, in which he comments: "there is a small subset of children who may be (emphasis my own) particularly vulnerable to vaccines if the child had a precondition like a mitochondrial defect...."

What she omits to mention is what Dr Amaral says directly before this: "So I think it's pretty clear that, in general, vaccines are not the culprit. There has been enough epidemiological evidence showing that if you look at children that receive the standard childhood vaccines that, if anything, those children are at slightly less risk of having autism than children that aren't immunised." Whatever your feelings about this exchange, Dr Amaral—one autism researcher amongst many thousands—is simply expressing an opinion; his conclusions are not based on actual research. It remains a theoretical risk in a very rare number of cases. Do we need to continue our investigations to find more answers? Absolutely; as the parent of a child with autism I want to know as much as possible. Finally, Ms Lefroy seems to me to be a little unclear how vaccines actually work. She suggests: "We can change the way they're administered (using drops instead of injections, so the virus can be broken down by the immune system's natural defence mechanisms before it gets into the bloodstream, instead of being propelled straight into it at full strength)."

Oral vaccines are not safer than injectable vaccines, and are sometimes even stronger, as they are live (but weakened) vaccines rather than killed. They are not broken down before going into the bloodstream; the immune system simply reacts to them, like it should. I could go on, but I won't. When deciding whether to vaccinate their children or not parents have to weigh up the risks (of side effects) and benefits (prevention of disease). Unfortunately, vaccines have become a victim of their own success and younger parents are unable to remember the days when infectious diseases such as polio terrorised communities. That's tipped the balance, leading some parents to worry (sometimes excessively) about side effects. If one parent, or two or even three elects not to vaccinate their kids that's fine; their children are still protected because there's not enough unvaccinated individuals in their community for an infectious disease to take hold. If, however, vaccination rates drop below a certain level, as has happened in some areas, such as after the autism scares, then it becomes a real problem and illnesses we thought we'd eradicated can make a comeback.

That's happening right now. Over the last 12-18 months or so, I have personally diagnosed and confirmed by throat swabs 30 or so cases of whooping cough, mostly in children. This is not unusual or exceptional; GPs all around Australia are doing the same. In the last few years, we have been in a large upswing of whooping cough case diagnoses, numbering in the tens of thousands. In fact, in other areas, particularly the eastern suburbs of Sydney and the far north coast of NSW, where immunisation rates have dropped to alarming levels due to vaccination scares, the rates of diagnosis of whooping cough are far higher than where I work. As of a few years ago, I had never seen a case of whooping cough (despite having working as a doctor in Australia for twenty-one years). Also, just last week, I received yet another notification from the Public Health Unit of measles cases being diagnosed in the south west areas of Sydney and the Southern Highlands. This is real, this is dangerous, and yes, this is scary. Why? Whooping cough in an infant is terrifying, a medical emergency. They can damage their lungs permanently, get brain damage from lack of oxygen to their brain, and they can die. In all, five Australian babies have died from whooping cough since 2008. Imagine being the parent of one of these children. As for measles, well, don't get me started. Measles is just plain bad. One in 20 children who get measles get pneumonia as a complication. For every 1000 cases of measles, one to two children will die. Yes, die.

So, where do we go from here? Do you vaccinate your child? Well, of course, the choice is yours. If it were me, (and remember, if I had another child he or she would have a higher chance of having autism) it would be a no-brainer—vaccinate away. In her article Ms Lefroy claims to be concerned about parental anxiety surrounding vaccines. Funny then that she then proceeds to create anxiety based on a theoretical risk that they may contribute to autism in a tiny minority of cases, whilst ignoring the all too real risk of discouraging vaccinations—the resurgence of potentially disabling, life-threatening and preventable diseases. Dr James Best is a GP and the father of three boys, one of whom has autism. All three of his sons have been completely vaccinated.