For reasons that will become clear, I feel the need to begin this by trying to prove I’m pro-vaccine. Here goes.

To my knowledge, I have always kept my son exactly on the vaccination schedule required by our state of Michigan. Now almost 15 years old, he is fully vaccinated according to public-health recommendations.

I’ve also kept myself on the recommended vaccine schedule and I pester my doctor about whether there are any vaccines I am missing. By some measures, I am actually more vaccinated than “necessary”; the HPV vaccine is not specifically recommended for women in their forties, but I bothered to get it for myself when it became available a few years ago. I did so in part because I thought I would sound more convincing when I urged young people to get it – which I do, all the time, because the HPV vaccine can help prevent cervical cancer, anal cancer, throat cancer and genital warts.

But I suspect all that testimony won’t matter given what else I’m about to say. Because as soon as one questions anything about vaccines – as soon as one expresses any doubt or concern about any vaccine practice – one risks being labelled an “anti-vaxxer”. Or at least represented as a kind of gunrunner to the anti-vax camp.

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As American historians of science of the same generation, Mark Largent and I have run into each other professionally for almost two decades. So when he showed up for a bookshop signing of my new book, Galileo’s Middle Finger – about the sometimes fraught relationship between scientists and activists – I thought he was just being collegial. Instead I discovered he wanted to talk about what had happened since he had published Vaccine, a book that tries to unpack why so many parents are resisting vaccinations for their children.

In his work, Largent refuses to take sides with either a) the anti-vaxxers, who think vaccines cause disorders such as autism, or b) the anti-anti-vaxxers – let’s call them the vaccine zealots – who think any parent who resists any vaccination is a dangerous idiot. Even though Largent is easily as “pro-vaccine” and pro-science as I am, among the frenzied zealots his sympathy for resister parents has marked him out as a heretic.

Talking with him over coffee a few days after the signing, I learned that, like other scholars whose misery I trace in my book – who have put forward challenging ideas about gender identity, sexual orientation, the nature of rape and childhood sexual abuse – Largent didn’t wade into his chosen topic naive about the potential for upsetting someone. Nevertheless, like those other scientists, he was caught off-guard by how difficult it has been to make his voice rise above deeply embedded dogma and polarised debates to suggest a different way of thinking about things.

A professor at Michigan State University, Largent tries in his book to do something potentially very useful: to sort out how to think about the “nearly 40 per cent of American parents [who] report that they delay or refuse a recommended vaccine for their children”. Refusing to write off those parents as anti-science, Largent finds in fact that “the percentage of [hardcore] anti-vaccinators in the US has held steady throughout the last 100 years at about 3 per cent of the population”. In this category, he counts people who consistently refuse all vaccinations: some religious groups such as Christian Scientists, some minority groups such as the Amish, and some people who are firmly against modern western medicine. Largent purposely does not include people who resist particular vaccines or who deviate from the mandated schedules.

So, controversially, he chooses not to label as “anti-vaxxers” the likes of the actress Jenny McCarthy, who has suggested that holding all children to the same vaccination schedule might severely harm some of them. McCarthy’s own son was diagnosed with autism after he suffered febrile seizures the night following half a dozen inoculations, and she has publicly speculated that his problems were due in part to the vaccines. Her move has led to a website, jennymccarthybodycount.com – which blames her for over 9,000 infectious disease deaths since June 2007.

Largent also bucks the usual trend among the sometimes self-righteous zealots by refusing to see public-health vaccine recommendations as a purely scientific prescription. In fact, he calls the recommended childhood vaccination schedule “a political artefact” – not a simple blooming of the science but a wrangled set of mandates and recommendations that it is not unreasonable for parents to question.

He prefers to call McCarthy and most other parents who doubt or hesitate “vaccine anxious” rather than anti-vaxxers, and suggests that doctors try to understand why parents might resist jabs for their children. For saying this, some have accused him of being part of the problem of vaccine non-compliance. This is a grave charge; if enough people refuse vaccinations for diseases such as polio, our “herd immunity” will be put at risk, and those children and adults who are too medically fragile to receive vaccines – perhaps because their immune systems have been weakened through illness – will end up at risk of severe disability and even death.

Talking to him over that coffee, I got the sense Largent is not sure what is worse: not being heard because he doesn’t fit in easily on either side of the public vaccine debate, or

being positioned as an anti-vaxxer because he dares to try to think deeper about the history and the facts of vaccination campaigns.

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To understand Largent’s argument, it’s useful to consider what a child’s vaccine schedule now is. US public-health officials recommend that in the first 18 months of life a child receive no fewer than 25 vaccinations. By the age of six, the appropriately vaccinated American child will have been subject to about three dozen vaccinations. In Britain, the schedule begins at two months with three injections: a pneumococcal vaccine, rotavirus, and a combination jab that protects against diphtheria, tetanus, whooping cough, polio and Hib, a type of bacterial infection. There are three more jabs at three months, another two at four months, and six more before starting school. That’s a lot of interventions for a parent to manage in a short space of time.

The number was similar when my own son was little and, talking to Largent, I remembered with some surprise that I could have reasonably been labelled a “vaccine-anxious parent”. My maternal instinct was riled with every new round of shots and cries and tears: I remembered one particular visit to our paediatrician when my gut instinct had a sharp argument with my brain. I can’t even remember what the vaccine was; I just remember that Gut was yelling, “Enough already! Stand between our baby and that needle!” Trying to stay calm, Brain answered: “Vaccines are safe, and necessary not just for our baby’s health but for the health of those around him, especially children more vulnerable than him . . .”

That one time, I asked the nurse if I could see the written literature on this vaccine. I wanted more information not because I was going to refuse the shot, but because I wanted Brain to shut Gut up. She looked shocked and annoyed and told me testily that there wasn’t any information available. The jab was just compulsory.

No pamphlet in the box, for parents? I asked.

No, she said.

I suddenly regretted even asking. Would I be labelled a “worried” mother, or worse, a “non-compliant” one?

Fortunately, our doctor came into the room at that moment. He knew that I had a PhD in history of science, and that I am a deep believer in science, in evidence-based medicine, in public health and so also in vaccines. Maybe because of that, or maybe just because he’s a good doctor, he quickly understood the situation. He went to his computer and printed out several pages of information about the vaccine. He gave me time to read, and waited for me to say “OK” before telling the nurse to proceed.

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Not everyone is as sympathetic to anxious or resistant parents as our doctor was. ­Writing on a blog under the pen name “Orac”, David Gorski, a surgeon and professor at Wayne State University in Detroit, has lambasted Mark Largent for talking about “vaccine-anxious” parents rather than “anti-vaxxers”. Gorski calls Largent “clueless” and insists that “the concerns of these parents are almost always rooted in pseudoscience, fear-mongering, and outright scientific misinformation”.

He goes on: “What ‘moral concern’ could lead parents to leave their children unprotected against vaccine-preventable diseases, particularly deadly ones?” How dare Largent suggest that paediatricians “address their concerns”, he writes, “as if paediatricians don’t try to do that every time a parent brings her child for a well-child visit and baulks at allowing her child to be vaccinated”?

I wonder if Gorski would have been appalled at my hesitation in my ­paediatrician’s office, like the nurse was. But here’s the thing: I don’t think my anxiety was rooted in pseudoscience, fear-mongering or outright scientific misinformation. While Gorski might want to write me off as a bad and anti-scientific mother, in most clinical encounters a mother asking for data about medical necessity, safety and efficacy before consenting to an offered medical intervention would be seen as a good and scientific mother. So why are vaccines treated in such an exceptional way? Why are they seen as different from most interventions in medicine and public health – requiring old-fashioned paternalism and even heavy-handed legal compulsion?

First off, as every vaccine zealot will (rightly) tell you, vaccines are not your usual sort of medical intervention. To state the obvious, with few exceptions (such as the tetanus vaccine), vaccines don’t just protect the individual being vaccinated; they also help to create “herd immunity”. It is hard not to look at the history of diseases such as polio, diphtheria and smallpox and not feel motivated to sing whatever rousing song will convince everyone to enlist in the army of the vaccinated.

Vaccine zealots also understand vaccines (again, rightly) as being different from other medical interventions because they are subject to higher levels of safety monitoring. They are, as a class, arguably the safest type of medical intervention we have in the world. Any time a vaccine is found to be unsafe or is even perceived as potentially unsafe, public-health campaigns may be put at risk, so most public-health officials are quite vigilant about safety-testing before releasing vaccines into the market and about monitoring them afterwards.

Finally, the history of terrible falsehoods that have been spread about vaccine safety causes in anti-anti-vaxxers the kind of fervour you should expect to find among people who feel their enemies have cheated. In terms of major falsehoods about vaccine safety, best known is the case of Andrew Wakefield in the UK, who claimed to have evidence of a link between the MMR (measles, mumps and rubella) vaccine and autism. In 2003, the investigative journalist Brian Deer began to uncover evidence that Wakefield didn’t just have his data wrong, but had actively misrepresented it. (The Lancet, which had published Wakefield’s work in this area, finally retracted it in 2010.)

In Galileo’s Middle Finger, I write about another major case of falsehoods spread about a measles vaccine. This involved the book Darkness in El Dorado, published in 2000 by the self-styled journalist Patrick Tierney. He suggested that the geneticist James Neel purposely conducted a Nazi-like eugenics experiment on the Yanomami people of the Amazon by giving them a vaccine that caused a measles outbreak. Tierney was wrong: the epidemic started before Neel arrived in Yanomami territory, the vaccine didn’t cause measles, and Neel and his team did everything they could to race ahead of the disease to vaccinate those at risk. But Tierney’s work has fed ­anti-vaxxers and spread false beliefs about vaccines.

Given the Wakefield and Tierney falsehoods, the high safety and efficacy rates of vaccines, and the history of vaccine success worldwide, it is hardly surprising that some public-health advocates see vaccines as the biomedical equivalent of Nelson Mandela.

You can guess what that makes parents who resist.

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So why isn’t Largent – and why aren’t I – a vaccine zealot? Well, despite the understandable passion of the vaccine fundamentalists, there are some inconvenient facts that are often overlooked in public debates about vaccines. Noticing them won’t make you an anti-vaxxer but they can make you feel like a vaccine heretic.

First, consider the question of necessity. Not all illnesses for which vaccines exist are as grave as polio or smallpox. Take chickenpox. Some American states have made the chickenpox vaccine mandatory – keeping children out of school unless they get it – ­after a lot of heavy lobbying by its manufacturer. But it is reasonable to ask, as I did, if it wouldn’t be just as safe to let your healthy child catch chickenpox, which is a minor disease for most healthy children, instead of giving them the vaccine. (That is the strategy of the NHS in Britain: it does not routinely offer the jab, claiming “there’s a worry that introducing chickenpox vaccination for all children could increase the risk of chickenpox and shingles in older people”.)

Next, consider safety: all vaccines do carry some risk – even if it is only a very, very small one. Some vaccines, in fact, are not generally given to the public because of concerns about safety. (The anthrax vaccine would be a good example here.) It is not completely unreasonable for parents to ask about safety concerns with vaccines.

Finally, consider the influence of money in the public-health system. Make no mistake: vaccines are a boon to big pharmaceutical companies, and the companies that make and push vaccines are the same kind that have been repeatedly fined for all sorts of bad behaviour where drug marketing is concerned. Moreover, studies consistently show that financial ties to the pharmaceutical industry influence the behaviour of doctors and policymakers – and yet many in those groups maintain such financial ties anyway. I’ve seen British medical journals that are normally vigilant about conflicts of interest “forgive” failure to disclose funding from vaccine-makers by an ethicist who pushes those companies’ vaccines as “necessary” in those journals and in the mainstream press.

Monetary influence on politicians’ decisions about vaccines is even easier to find. One example: there has been huge resistance to the HPV vaccine, which prevents a sexually transmitted disease that causes cervical cancer, because religious groups argue (against the scientific evidence) that it may encourage promiscuity in teenagers. Yet Rick Perry, the then Republican governor of Texas – who might be expected to pander to the Christian right’s abhorrence of the vaccine – suddenly decided to mandate the HPV vaccine for schoolgirls after a series of donations from the vaccine’s maker.

The facts listed above might lead you to wonder if all this suspicious behaviour isn’t ultimately as dangerous to public-health vaccine campaigns as someone like Jenny McCarthy is claimed to be – because it breeds cynicism, conspiracy theories and distrust of the medical profession itself.

But as Largent has been learning, you can’t say these things. You have to subscribe to vaccine exceptionalism – vaccines are all necessary, safe and effective and should never be questioned! – or risk being crushed. In the zealots’ eyes, in the battle to vaccinate the world, moderates must be crushed so that children can be saved.

The problem is that the zealots’ approach doesn’t work. Studies show that haranguing people with proof that vaccines are safe doesn’t increase parental compliance. Ironically, if you really take science seriously, you have to admit that beating people over the head with scientific studies generally doesn’t get them to be act in more rational ways, particularly if some important parental psychology is getting in the way.

If you want to understand and reduce vaccination non-compliance, what probably has to happen is what Largent has been trying to do. You have to work to achieve a subtler understanding of parental decision-making, along with a recognition that ­public-health campaigns aren’t Pure Science but are influenced by politics and money (although maybe they shouldn’t be). You have to stop talking about “vaccines” as if they were all one thing, and stop talking about vaccination schedules as if they were simple products of value-free science. You have to stop claiming “we” have science and “they” have stupid.

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Mark Largent is working now with public-health officials with the goal of improving vaccination rates by understanding the reasons why a reasonable, well-informed parent might decide to opt out of vaccinations.

Like Largent, I wonder if this more respectful, more generous approach will work. I wonder if it has any hope of even catching on as a public-health approach. Ultimately, given the perceived risk that moderate voices such as Largent’s allegedly present in this matter, the idea of taking vaccine-anxious parents seriously may be declared too heretical to be preached within the church of public health.

Even if Largent is declared a dangerous heretic by those who claim to be the true defenders of vaccine science, he likely won’t end up as badly off as many of the scientists I interviewed for my book. He probably won’t end up accused of genocide, accused of having sex with a research subject, having 20,000 people email his university president calling for his dismissal, or having to fight in court for his right to publish results of his research, as various of the beleaguered scholars I interviewed were.

Moreover, Largent is a big boy with a tough skin. I am not too worried about him. The people I am worried about are the ones who may end up harmed because we couldn’t bring ourselves to think more clearly about what is really going on in vaccination campaigns – because we couldn’t see that it was time to give up on the dogma and bring in the heretics if we want to save more souls.

Alice Dreger is the author of “Galileo’s Middle Finger: Heretics, Activists and the Search for Justice in Science” (Penguin Press)