Influenza vaccination season is upon us. Although there is a general consensus – supported by science — that immunization for things like the flu is effective, some people hesitate and even refuse to have themselves or their children vaccinated, whether for the flu or other diseases.

Maya Goldenberg, a philosophy professor at the University of Guelph, says their concerns are rooted in public distrust of scientific consensus and the institutions associated with it. At U of G, Goldenberg researches vaccine hesitancy and vaccine refusal, and the role of trust and distrust in our attitude toward science.

Question: You’re a philosopher. What is the basis of your interest in immunization?

Maya Goldenberg (MG): I work in an area of philosophy of medicine called medical epistemology. Epistemology is interested in knowledge: How do we know what we know? Are our knowledge claims justified?

Because I spend a lot of time thinking about medical evidence, I found myself initially puzzled by the reluctance of a minority of the public to accept the scientific consensus on vaccines. With so much evidence available to discredit the so-called “anti-vax” theories—that vaccines cause autism, that the mercury in vaccines cause neurological damage, and others—I wondered what evidence it would take to finally change the minds of vaccine skeptics.

A little study of the issue led me to see that I was asking the wrong question. This debate does not hinge on scientific evidence but on the complex socio-scientific terrain where science, values and policy meet.

Prof. Maya Goldenberg

Q: What is the scientific evidence for vaccinations having an overall beneficial effect on individual and collective health?

MG: There is very little room to debate the overwhelming scientific evidence in support of vaccination for individual and public health. Even when we consider the many weaknesses in the “evidence base” of medicine—industry bias, poor demonstrations of efficacy, suboptimal post-marketing surveillance—there is still good reason to accept the consensus on vaccines.

The data is robust: the clinical outcomes are dramatic, vaccine technology and the mechanisms by which the immune system responds to vaccine antigens are well-understood, and there are diverse sources of reliable epidemiological data showing drops in disease frequency and no temporal correlation to rates of autism or various neurological conditions among children.

What has interested me was not the weight of evidence in favour of vaccines, which is well-established, but why some people do not accept the consensus view.

Q: How would you describe vaccine hesitancy, and how common is it?

MG: Vaccine hesitancy is a feeling of uncertainty or ambivalence about vaccines. “Vaccine hesitancy” has surpassed “vaccine refusal” as an area of research interest for public health because vaccine refusal — a behaviour — is far less common than vaccine hesitancy — an attitude.

Canadian research suggests only 1.5-2 per cent of parents with young children are vaccine refusers; this small number has remained steady for some time. There is also reason to believe that vaccine refusers are highly unlikely to change their views, so outreach and education will likely fail.

Vaccine hesitators are more common. About 25 per cent of Canadian parents with young children hold some sort of “hesitancy” or uncertainty regarding vaccines.

Q: Why are some parents hesitant about child vaccinations?

MG: The social scientific research points to common themes and concerns, including broad safety concerns, concerns regarding rare vaccine side effects and questioning the need to provide vaccines to healthy individuals. There are also concerns about overloading children’s immune system with too many vaccines in a short period of time.
Those concerns are usually expressed alongside an outline of an alternative strategy for protecting their children from harm, including alternative medicine, or a belief that “natural immunity” acquired from the actual diseases is preferable. Some also have a belief that those diseases aren’t so bad, or that disease can be avoided or the effects minimized by health strategies like eating organic food and prolonged breastfeeding.

Q: What are the potential negative effects of vaccine refusal? Have there been serious health consequences as a result?

MG: Vaccination rates in Canada are still very high, but unvaccinated children tend to live in geographical clusters, so outbreaks have occurred. Children have been hospitalized, and some have died. Containing an infectious disease outbreak is also extremely costly. It strains our health-care system and certainly compromises patient care in other areas, as health-care resources are diverted to outbreak containment.

Q: In the minds of opponents of scientific consensus, whether related to vaccinations or other subjects, where does authority and credibility reside, if not with science?

MG: People trust the sources that they believe to have their or their children’s best interest at heart. On vaccines, parents cite their family doctors, friends and family members as resources. If the family physician, or family and friends cannot fill that trust gap, one might find online communities of similarly worried parents.

Some parents think institutional medicine and public health may be more concerned about community health — herd immunity — than the health and safety of each individual. Or some parents may believe that the institutions are directed by profit-driven pharmaceutical and biologics companies, and therefore turn a blind eye on safety concerns.

Q: Could it be said that there are legitimate reasons behind this distrust, such as evidence that science has previously erred?

MG: The history of medicine chronicles instances of severe abuse and negligence, which arguably provides reasons for rational mistrust of health care. Some past offences have inspired major correctives, such as the formulation of robust ethical guidelines on human research subjects. Other offences, like poor treatment and under-treatment of marginalized communities, still endure.

There have been past errors regarding vaccines that should be acknowledged. There have, for instance, been occasional manufacturing errors that resulted in tainted batches of vaccines.

But such errors should only breed mistrust if they were caused by wilful negligence and if those careless practices continued. This is not the case with vaccines. Measures were brought in place to regulate and monitor vaccine manufacturing, transportation and storage, and thereby make it unlikely that past errors would repeat themselves.

Q: Are vaccine hesitators misguided or simply denied access to relevant, convincing evidence?

MG: There is some appeal to the common view that people question vaccines because they do not understand the science, but my research shows that this is not the driver of vaccine hesitancy. There have been decades of vaccine education and outreach, and the numbers of vaccine refusers and hesitators are not changing.

There is something other than education that is lacking. I see vaccine hesitancy as a symptom of poor public trust in scientific institutions.

Public health cannot fulfill its population health goals without high levels of public compliance regarding their health recommendations. That means that public health’s institutional goals include not just the best science and most reasonable policies but also maintaining the public trust. As long as science fails to meet that last mandate, persistent vaccine hesitancy is a failure of the scientific institutions rather than the moral or epistemic failings of the public.

Q: How do we cultivate broad-based trust in science?

MG: By addressing those points of mistrust and doing it transparently so that the public can appreciate the effort. Public trust will likely grow from there.