Inside the distrust of vaccine science

Vaccines are one of the most important defences we have in the fight against Covid-19. They keep hospitalisations down and save lives. Unsurprisingly, the topic of vaccination has been in the spotlight since Delta arrived in our communities and now Omicron.

However, vaccines have been part of our health prevention and protection toolkit since the late 1700s and have led to eradication of debilitating infections such as smallpox and suppression of diseases such polio and measles. These health gains are on par with advancements in sanitisation and distribution of clean drinking water, with the World Health Organisation (WHO) estimating 2-3 million deaths are prevented each year by vaccination.

Yet despite life- and cost-saving benefits, vaccines attract far more controversy than any other public health intervention, if public rhetoric and parliamentary protests are anything to go by. While New Zealand has achieved impressive results with our Covid-19 vaccination rates, surveys conducted prior to the arrival of Delta in 2021 found that about a third of people were unsure about being vaccinated.

In response to this, and to help with misinformation and vaccine hesitancy in the future, we are launching New Zealand’s first survey to find out what Kiwis want to know about vaccines and their preferences for vaccination. But first, let’s identify the problems we have seen with information during the pandemic.

The rise of the ‘infodemic’

Vaccine hesitancy and controversy can be driven by a lack of information to support informed decision-making. Yes, there is a huge amount of information out there, but it may be incorrect, outdated or not what people want to know. What’s more, much of it uses language, numbers and statistics that are unfamiliar - for example, R0 value, vaccine ‘coverage’ or ‘effectiveness’, or ‘vaccine escape’.

Faced with such confusion, it is natural to feel overwhelmed - in fact, the World Health Organization has recognised this overabundance of information as an “infodemic” with the potential to undermine public health efforts to manage the pandemic. Too much information given in a short amount of time, combined with knowledge gaps and confusing messaging, makes it hard for people to trust information and know what to do to protect their health and their communities.

A recent report from the Academy of Medical Sciences found two out of three British people don't trust medical evidence, with the same number preferring to trust information from friends and families. Why is it that so many people distrust medical evidence?

The origin of medical evidence and mistrust

Evidence for the efficacy of medications comes from rigorous scientific research governed by strict rules and regulations. But medical research has suffered high-profile scandals which have shaken public trust in medical evidence. Reports of biased results in industry-funded studies such as the Rofecoxib and Paroxetine debacles have fuelled scepticism towards scientific studies as a whole. With industry funding the most common for medicine trials, it might come as no surprise that the public may feel medical evidence is not to be trusted. And while industry funded trials have been highly visible offenders, reports of biased or falsified evidence can be found elsewhere. For example, in the MMR vaccine scare and the Boldt scandal, risk of falsified results is a problem outside of industry as well. Public perception of the pharmaceutical industry continues to be poor.

The numbers show, however, that these infractions are few and just because some studies have been biased or fraudulent doesn’t mean all research should be distrusted. Why is it then that we continue to distrust medical evidence?

Part of this may be due to how our brains are hardwired. We are more likely to remember bad news and scandals than good news - it’s a mechanism evolved to protect ourselves. Distrusting medical evidence can be seen as evolutionarily protective because incorrect evidence can have life-threatening consequences. Because our brains assess that the risk does not outweigh the reward, we become hyper-critical as an extra precaution. There is also the effect of uncertainty - as we don’t know which studies will have biased results, our minds respond by not trusting evidence in general.

Communicating evidence

New medical evidence is usually communicated first to health providers and researchers before the public. It is usually written with professionals in mind, rather than the public, making it difficult for most of us to understand. Most evidence is published in academic journals, which are not easily accessible. These barriers further influence our trust in medical evidence, as there is a lack of information about how evidence that informs health advice is found. Too often we are just presented with a fact or statistic about the medicine without being told how or where this information comes from. This creates uncertainty and again affects our trust in the information that is presented to us.

Use of medical evidence in practice

Most of us receive medical advice or evidence when we visit a health provider. Yet why is it that two-thirds of people would rather trust friends or family than medical evidence and healthcare professionals? There are several factors at play. First, psychology tells us that we are more likely to value the opinions of those we perceive as similar to ourselves. This effect is also found in doctor-patient relationships – patients who share the same ethnicity as their general practitioner are more satisfied with their doctor.

Secondly, the way we get information from our friends or families is likely to be in the form of stories told based on their experiences. A review found that narrative information influenced decision-making more than statistically based information.

Lastly, the information we currently get through patient information leaflets has been described as ‘impenetrable’ and ‘unreadable’ to the layperson. This difficulty with understanding medical information further adds to lack of trust in healthcare providers and medical evidence.

So, what about vaccines?

First off, we need to consider people’s values and preferences when it comes to health information. For vaccines, there are many features such as effectiveness, duration of protection and side effects which can influence whether people wish to take a vaccine or not. One way to explore and analyse public preferences for various vaccine features, and what trade-offs they are willing to make between different features, is the use of a ‘discrete choice experiment’, otherwise known as a DCE. DCEs have long been established as a valid method of exploring preferences and have been used widely in economics and marketing.

This is what we will be doing with our vaccine survey.

The findings will reveal what New Zealanders want to know about vaccines and what they want in an ‘ideal’ vaccine. The results will help inform policy makers, health professionals and vaccine developers on what to communicate and prioritise, and what vaccine features to consider first when developing and introducing future vaccines to the public.

Similar studies have already been done overseas in the UK, Europe, Asia, US and Australia, on preferences for vaccines such as the flu, chickenpox and meningitis. The findings have been used to inform health promotion initiatives and vaccine campaigns to make sure information the public wants is out there and easily available.

Our survey will provide the same for New Zealanders.