You don’t have to surf many news sites these days before bumping into stories about low vaccine uptake. Whether it’s reports on the impact of children missing their measles jabs, or the drop in people reporting for the new flu shot, the topic is rarely far from the headlines.

Vaccines are biological preparations designed to increase our immunity to specific diseases. According to the World Health Organization (WHO), they are now available for more than 25 debilitating or life-threatening diseases, including measles, polio, tetanus, diphtheria, meningitis, influenza, tetanus, typhoid and cervical cancer. 

Vaccinations are the vehicle used to deliver vaccines to our bodies. In many countries, recipients pay little or nothing for vaccinations and the process is simple – usually one or more injections, or even a spray in the nose. And we know they work: Smallpox, an ancient disease that was fatal in around 30% of cases, was officially declared eradicated in 1979 after a collaborative global vaccination programme.(1) While in October this year, it was announced that the second of three polio strains has now been eliminated. Yet, also this year, WHO declared “vaccine hesitancy” one of the top ten greatest health challenges. The impact of this reluctance or refusal to vaccinate can be enormous; for example, in the case of measles, a newly-published study (November 2019), found that the measles virus can cause long-term damage to the immune system, wiping out immunity to other diseases.(2) Even minor reductions in MMR vaccination driven by vaccine hesitancy are likely to have substantial public health and economic consequences.(3)  

So, what prompts some people to turn their backs on the vaccines on offer? With the help of Dimensions rich and interconnected data, we attempt to find the answers. We also uncover some of the latest findings, along with who’s researching, publishing and funding them.

The “fake news” factor

By 2000, the US had effectively eliminated endemic measles, yet this year saw the biggest outbreak since 2014, with 1,095 confirmed cases by June 2019.(4)  Other countries around the world are experiencing similar, often startling rises in measles infection rates.(5) 

The measles vaccine is usually administered alongside vaccines for mumps and rubella (German measles) to young babies in a single injection known as the MMR jab. This is followed by a booster shot before they attend school.

However, in 1998, Andrew Wakefield and colleagues published an article in The Lancet, which suggested a link between the MMR jab and autism and bowel disease.(6) The news coverage the article received was enormous…so too was its impact, with some researchers blaming the increasing numbers of parents refusing to let their children receive the MMR jab directly at its door.(7,8)  

Despite the fact that the original article was later retracted and the UK’s General Medical Council removed Wakefield’s license to practise as a doctor, there is a sizeable group of people who still believe Wakefield’s version of events to be true. Even though countless other studies have refuted his article’s findings.(e.g. 9,10,11) 

The reinforcement of misinformation

This continued support for the Wakefield research could be due to the inaccurate information currently circulating around childhood vaccines; particularly online.(12,13) And a recent study shows that people who believe that vaccines are dangerous, tend to favor sites and webpages supporting their views, making it difficult for researchers and government bodies to persuade them otherwise.(14)  Stronger still, it suggests that introducing contradictory information to these websites may only end up reinforcing anti-vaxxers’ original opinions.(14) 

A Scientific Reports article may help to explain this behavior. The study found that when participants had their strongly-held (in this case, political) views challenged, an area of their brain thought to be linked to self-identity and negative emotions was activated – in other words, they felt personally under attack and became defensive.(15)

Another study points to the “Dunning-Kruger effect”, which occurs when people believe their cognitive ability to be greater than it actually is. In one study, more than a third of participants thought they knew lots, and even more than doctors and scientists about the causes of autism. This overconfidence was often linked to opposition of mandatory vaccination policies.(16)

Unsurprisingly, the stories that people share in person and online about vaccines can prove highly influential. The HPV (human papillomavirus) vaccine is recommended for boys and girls aged between 9 and 12 to prevent HPV infections that can lead to cervical cancer. However, a 2017 study found that parents who had heard stories about people who were either harmed by the vaccine, or went on to develop one of the diseases it is designed to prevent, were much more likely to refuse or delay the injections for their children.(17)

Bridging the knowledge gap

In the case of HPV vaccinations, several studies have found that lack of education about vaccines is another driver of hesitancy, with low awareness likely to influence parents’ decision-making.(18)  And some studies suggest that responsibility for increasing awareness should lie with healthcare providers, as parents are more likely to approve the vaccination if their physician recommends it.(19, 20) However, research suggests that many healthcare providers remain unprepared or reluctant to address the vaccine conversation with hesitant patients.(21)  Most vaccines protect both the vaccinated individual and the community at large by building up “herd immunity”, but according to a group of researchers in Germany, explanation of this concept remains rare in vaccine advocacy. Their 2017 study found that explaining it helped to  improve vaccination willingness.(22)

And the other factors at play…

Interestingly, one study published in Social Science & Medicine this year found that parents with high levels of conspiratorial thinking and needle sensitivity are more likely to delay vaccinations for their children. While in the case of HPV, concerns over moral purity and sexual deviance also play a role.(23) 

In Australia, researchers discovered that compared to parents who support childhood vaccination, those who are against it (rejectors) or sit on the fence are more likely to be advocates for the rights of the individual. In addition, rejectors are more likely to object to the idea of putting impurities in the human body.(24) 

While a US study uncovered that for some objectors, the issue is a religious one, often based on the use of aborted human fetus tissue in the rubella component of the MMR jab and animal gelatins used in vaccine production.(25)

Here are a few facts we gleaned from the free version of Dimensions by running a topical search for “vaccine hesitancy” (NOTE: all data for this article were extracted from Dimensions on 11.04.19).

Researchers

The auto-generated analytical views tab reveals that the most published researcher on the topic is Dr. Ève Dubé of the Institut National de Santé Publique du Québec in Canada. Her research focuses on the socio-cultural field surrounding infectious diseases prevention, with a particular interest in vaccine hesitancy. In fact, 30 of her 96 publications listed in Dimensions touch on the topic.

Figure 1: Dr. Ève Dubé’s profile page in Dimensions

In Dimensions, publications are linked to other content types to provide a full view of the research landscape and easy exploration of the connections between relevant grants, clinical trials, patents, and policy documents. A quick look at Dr. Dubé’s profile page shows she has been awarded three grants by three different organizations to investigate the topic: the most recent explores how the vaccination views of chiropractors and naturopaths influence their treatments.

Publications

Vaccine hesitancy is a relatively recent research topic. A topical search on the phrase in Dimensions returns 693 publications; although the earliest entry dates back to the 1940s(26), there was only 1 paper published every few years until 2013 when 26 were published. The number has continued to rise steadily and this year alone there have been 208 new articles.

Figure 2: Publications on the topic of vaccine hesitancy, by year.

Sort these by citations, and we can see that the 2014 Vaccine article Understanding vaccine hesitancy around vaccines and vaccination from a global perspective: A systematic review of published literature, 2007–2012 has received the highest number of citations to date (313) – 49% of these have been received in the past two years, which suggests it is still attracting a lot of interest. In fact, compared to other publications in the same field, it has received around 64 times more citations than average.

Figure 3: The Dimensions Badge detail page for the article Understanding vaccine hesitancy around vaccines and vaccination from a global perspective: A systematic review of published literature, 2007–2012 

In contrast, the article that received the most online attention, with an Altmetric score of 1,242, is the 2016 Pediatrics article Countering Vaccine Hesitancy

Figure 4: Altmetric information for the article Countering Vaccine Hesitancy

As we can see in Figure 4, much of the online activity around the article took place on news sites, Twitter and Mendeley.

Grants

Funding for research into the topic has risen sharply since 2013. While the trajectory for ongoing grants (the blue line in Figure 5) appears to be generally continuing its upward trend, the volume of new grants awarded follows a more erratic path. 

Figure 5: Volume of active and starting grants, 2010-2019.

This apparent fall in number (green line in Figure 5) may be due to an overall increase in the value of grants awarded, as we can see in Figure 6.

Figure 6: Funding amount allocated to vaccine hesitancy 2010-2019

A number of the grants exceed 1 million euros; for example, the Bill & Melinda Gates Foundation awarded 7 million euros to Johns Hopkins University in the US to “strengthen domestic institutions for ensuring adequate prioritization and financing of immunization program in India by providing strong technical evidence and addressing vaccine hesitancy concerns”.

If we look at the top five funders, four of them are based in North America (US and Canada), and have awarded more than 20 million euros between them. The other funder in the top 5 is the European Commission (4.3 million euros).  

Clinical trials 

There are 18 clinical trials in Dimensions that focus on vaccine hesitancy, with many testing ways to improve vaccine uptake. These include a University of Toronto trail which is experimenting with The CARD System (C-Comfort, A-Ask, R-Relax, D-Distract), which, among other things, will offer school pupils the opportunity to bring a support person to their vaccination session.

The next steps

For those attempting to address vaccine hesitancy, the path isn’t going to be easy. What’s clear from the research we’ve explored in Dimensions is that there isn’t one factor holding people back – the reasons are varied and complex, ranging from fear of needles and lack of awareness to concerns over the vaccines themselves.

For some, the key to tackling vaccine hesitancy lies in education; of healthcare professionals who can persuade parents that vaccination is safe, to parents (and children) themselves. For others, a multi-pronged approach using behavioral insights is needed to motivate the complacent, remove barriers for those who find vaccination an inconvenience, and add “incentives and additional utility for the calculating”.(27)

A sizeable group suggest the solution is for public institutions to increase their web presence(12), in particular getting passively involved in sites where anti-vaxxers are active so they can understand their motivations.(14) At least one study believes that while social media may be contributing to vaccine hesitancy. it may also prove the key to resolving it.(28)

Some creches are now refusing to take children that have not had their MMR jab, as are some pediatric practices. Australia has been experimenting with a ‘No jab, No pay’ policy which withholds three state benefits if parents don’t have their children vaccinated. However, some studies suggest that this approach might backfire among parents who are ambivalent toward vaccination.(24)

One thing is clear, with so much at stake, research into vaccine hesitancy is only likely to grow over the months and years ahead.

Dimensions’ wide range of content allows you to gain new insights into your chosen topic. Feel free to reach out to the Dimensions team to learn more about the content scope and coverage and see how Dimensions can help you find the most relevant results faster.

References

1 Standardization of smallpox vaccines and the eradication programme–a WHO perspective

2 Game of clones: How measles remodels the B cell landscape

3 Public Health and Economic Consequences of Vaccine Hesitancy for Measles in the United States

4 Measles: There is No Vaccine against Vaccine Phobia

5 Measles: a global resurgence

6 RETRACTED: Ileal-lymphoid-nodular hyperplasia, non-specific colitis, and pervasive developmental disorder in children

7 The MMR vaccine and autism: Sensation, refutation, retraction, and fraud 

8 Lancet retracts 12-year-old article linking autism to MMR vaccines

9 Measles, Mumps, Rubella Vaccination and Autism: A Nationwide Cohort Study

10 Early exposure to the combined measles–mumps–rubella vaccine and thimerosal-containing vaccines and risk of autism spectrum disorder

11 Autism Occurrence by MMR Vaccine Status Among US Children With Older Siblings With and Without Autism

12 Misinformation on vaccination: A quantitative analysis of YouTube videos

13 Vaccine hesitancy and (fake) news: Quasi‐experimental evidence from Italy

14 Polarization of the vaccination debate on Facebook

15 Neural correlates of maintaining one’s political beliefs in the face of counterevidence

16 Knowing less but presuming more: Dunning-Kruger effects and the endorsement of anti-vaccine policy attitudes

17 Stories about HPV vaccine in social media, traditional media, and conversations

18 A systematic approach to map the adolescent human papillomavirus vaccine decision and identify intervention strategies to address vaccine hesitancy

19 Provider communication and HPV vaccination: The impact of recommendation quality

20 Quality of Physician Communication about Human Papillomavirus Vaccine: Findings from a National Survey

21 Immunization attitudes, opinions, and knowledge of healthcare professional students at two Midwestern universities in the United States

22 On the benefits of explaining herd immunity in vaccine advocacy

23 Parent psychology and the decision to delay childhood vaccination 

24 Accepters, fence sitters, or rejecters: Moral profiles of vaccination attitudes

25 Religious Barriers to Measles Vaccination

26 The Knowledge of human virus infections of animal origin

27 Using Behavioral Insights to Increase Vaccination Policy Effectiveness

28 Vaccine Hesitancy: Where We Are and Where We Are Going