Sarah Chapman is a Lecturer in the Department of Pharmacy and Pharmacology at the University of Bath.
Vaccine hesitancy, or the delay or refusal of vaccination, has been listed as one of the top 10 global health risks of 2019 by the World Health Organisation.
Where safe and effective vaccines are available but not taken, vaccine hesitancy can mean that the unvaccinated individual is more at risk of infection and more likely to infect others. In the UK, rates of vaccine hesitancy are increasing for some vaccines. Simon Stevens, the Chief Executive of NHS England, has pointed to the role of social media in spreading false ‘anti-vax’ information to the general public.
Vaccine hesitancy beyond social media
Although online ‘anti-vax’ information is a relatively new phenomenon, ambivalence about pharmaceutical treatments is extremely common. An estimated one third to one half of all medications worldwide are not taken as prescribed. Psychologists have found that reluctance to take vaccines can often be understood in the same way as reluctance to take other forms of medication. People weigh up the costs and benefits of treatments, and where they feel that they do not need a treatment or have concerns about the negative effects (e.g. side effects, vaccination pain) they are less likely to take the treatment.
This means that there is often a mismatch between the perspectives of healthcare professionals and policymakers, and the patients they treat. For healthcare professionals, the idea that vaccinations, which typically have been tested through many large scale trials, may be harmful or unnecessary is often difficult to understand. Often it is assumed that a simple brief statement telling people that the vaccine is largely safe and will protect against illness will be enough to persuade someone to get vaccinated.
Healthcare professionals may feel baffled and frustrated by vaccine refusal and it can be tempting to think of vaccine hesitancy as arising from ignorance or simple messages seen online. But, this perspective underestimates the wealth of sources of information that people tap into when making judgements about medicines, and ignores the role that the characteristics of vaccinations and the healthcare system itself play in promoting vaccine hesitancy. Understanding why some people might be predisposed to be persuaded by fake news about vaccination can help us to combat this information.
Vaccinations as unnatural technologies
Looked at in one way, the use of vaccinations, often involving being injected with a weakened or killed virus, could seem like a strange and undesirable activity. Usually, humans studiously avoid putting substances in their bodies which are not food, and which do not look, smell or taste appetising. The notable examples of recreational drugs and tobacco may not appear appetising but affect neural reward systems. Eating or injecting ourselves with most highly processed chemical substances would be harmful and risky. It is no wonder that many parents think carefully about whether to have their children vaccinated.
For food, there is evidence that people may be biased towards less processed substances where we can identify a relatively simple origin. Which would sound more appetising to most people: A burger made from ground beef and no additives from a single cut of beef produced on an individual farm and a named farmer? Or a burger made in a factory from multiple cuts of beef from many different farms and containing many food additives?
This has led some to suggest that we have a ‘naturalness’ bias. Vaccinations, which are highly processed and far removed from most people’s daily experiences, may be a poor fit for the appetites instilled in us through millennia of evolution.
Cultural factors and religious beliefs are also important. Frequently new technologies are portrayed as invisible promoters of ills such as cancer, climate change and a host of social problems. ‘Modern health worries’ about the impact of new technologies, such as wind turbines and power lines, on health can make people reluctant to engage with healthcare. Suspecting that pharmaceutical companies and healthcare professionals are motivated by finances rather than the patient’s best interests may also lead to suspicion of vaccinations. For some people, rejecting the evidence-based scientific approach to evaluating risk and benefit of treatment may tie in with deeply held spiritual and religious beliefs; trusting themselves or trusting god for healing and survival.
Healthcare doesn’t always help
It is not surprising that healthcare organisations and professionals often need to be proactive in promoting vaccination. However, healthcare systems can sometimes be ill-equipped to overcome vaccine hesitancy.
Information provided about vaccination often flags the risks of vaccination far more extensively than the benefits. The information leaflet for one of the childhood measles, mumps and rubella (MMR) vaccines offered by the NHS includes one paragraph on how the vaccination protects against illness and several pages of warnings and information about adverse effects such as fever, upper respiratory tract infection and loss of appetite.
When understanding risks of vaccinations, patients might weigh how severe, probable and treatable a disease is against how severe, probable and treatable the adverse effects of the vaccination are. However, patients and healthcare professionals often misinterpret numerical risk information and over- and under-estimate certain types of risks. Although, these biases vary widely, and patients often overestimate the benefits of healthcare interventions, and the likelihood of side effects, and underestimate the likelihood that they will experience negative events such as cancer. This can make patients more reluctant to engage in preventative healthcare such as vaccination.
Informing patients about the risks and benefits of vaccination is fundamental to ethical medical care. If patients are not provided with information about risks of vaccination, how can they decide that it is appropriate for them? The perception that risks are being exaggerated or adverse effects minimised might also undermine trust in healthcare. Healthcare providers are the most trusted source of information about vaccination. However, the capacity to provide detailed personalised information may be limited by time constraints and knowledge.
The conundrum of adverse effects
When attending for vaccination, patients frequently receive additional information about adverse effects they might experience and how to manage these. But we know that identifying adverse effects is far from straightforward.
In placebo-controlled trials people frequently report adverse effects even when they’ve received the inactive placebo treatment, sometimes stating these are so severe they are intolerable. In one MMR vaccination trial, 190 of 581 children given the vaccination had a mild fever 1-6 days later, suggesting mild fever is a common adverse effect. But, 187 of 581 children given placebo had a mild fever in the same time period. Thus mild fever was common and largely unrelated to the vaccination.
In practice, this means that many adverse effects seen in vaccination clinics may in reality be coincidental symptoms of other illnesses, day-to-day activities, and stress. Recent studies have found that parents with pre-existing negative beliefs about vaccination tend to report more adverse events to flu vaccine perhaps because of a greater tendency to believe symptoms are adverse events, potentially reinforcing their beliefs.
Overcoming vaccine hesitancy
Vaccine hesitancy arises not simply from ignorance about vaccines, but also from cultural factors and beliefs that might be reinforced by patients’ experiences of vaccination. This means that many people may be open to persuasive fake messages about vaccination.
To reduce vaccine hesitancy and overcome fake news about vaccines, simple interventions focusing on numerical risk information are unlikely to be sufficient. Complex techniques which take into account the underlying roots of patients’ reluctance to be vaccinated, and take advantage of the voices of trusted healthcare practitioners, are needed.