It would probably be counterproductive to repeat them all here but the biggest vaccine myth of the late 20th century was the inaccurate claim that the MMR vaccine was linked to developmental disorders.
This has been thoroughly investigated and there is not a scrap of evidence to support it. Scientists, medical associations, health authorities and the vast majority of doctors and nurses say the MMR vaccine is safe and effective in preventing serious illness.
Yet the myth refuses to die.
This is very frustrating given that untrue rumours can cause people to opt out of recommended immunisations, sometimes opening the door for an epidemic of vaccine-preventable illnesses.
To deal with this, our instinct is usually to tell as many people as possible that the myth, misconception or unfounded rumour are false – we want to debunk the myth.
Busting the myth-busting myth
However, two new studies by Dr Brendan Nyhan, Assistant Professor of Government at Dartmouth College, suggest that ‘myth-busting’ does not work. Worse, it might actually reduce the chances that people will vaccinate.
Nyhan is a political scientist who founded a political fact-checking website more than a decade ago and has studied the impact of political attack ads in the United States – and how difficult it can be to undo the damage of a political smear, even when the accusation is false.
From there, he began looking at other areas where misinformation can change people’s behaviours. To his surprise, there was very little published research in this area, so he decided to do his own. The results are striking.
The first, published in the journal Pediatrics, looks at whether giving people information about measles and the MMR vaccine can help to overcome false beliefs, leading to increased uptake of recommended vaccines.
Participants were divided into five groups. One group of parents was given information explaining the lack of evidence linking MMR and development disorders; the next group was given text about the dangers of measles, mumps and rubella; another was provided with images of children who have vaccine-preventable diseases; and the fourth group was given a dramatic story about a child who almost died of measles, along with a fact sheet. The final group was given nothing.
It turns out that among parents who had started out with the least favourable opinions about immunisation, tackling myths about vaccine safety actually reduced their willingness to vaccinate their child.
The ‘correction’ backfired.
That MMR study published earlier this year has now been backed up by a new paper in the journal Vaccine. The study shows that correcting the myth that flu vaccines can cause influenza was ineffective.
“When we presented people with evidence against the common myth that the flu vaccine can give you the flu, they were less likely to believe in that myth but there was no corresponding increase in intention to vaccinate,” Dr Nyhan told Vaccines Today.
“Instead, respondents with high levels of concern about vaccine side effects were less likely to say they would get the flu vaccine during that flu season.”
So what do these two studies mean for parents, doctors and public health authorities committed to controlling infectious diseases? We asked Dr Nyhan:
“These studies suggest that correcting vaccine misinformation is unlikely to be an effective messaging strategy. In both studies, intention to vaccinate decreased among respondents with the least pro-vaccine attitudes after being exposed to information debunking a widespread misconception about the vaccine in question. Among these groups, who are least likely to vaccinate and therefore of greatest concern in public health, corrective information appeared to provoke people to reinforce their fears or concerns about vaccines rather than mitigating them.”
So is the best option to do nothing until researchers figure out what works?
“Doing nothing’ is definitely not a reasonable option. First, it’s of course scientifically and ethically important to provide accurate information – we’re not arguing against correcting these myths when they arise. But we should also try to learn more about what approaches would be more effective while also being realistic about the scope for messaging effects relative to other strategies. Working through trusted health providers (doctors, nurses, etc.) and community institutions (schools, hospitals, businesses, religious organisations, etc.) to promote vaccination is likely to be a more effective approach than information provision alone.”
What other vaccine-related questions will Nyhan’s team try to answer through research?
“We hope to learn more about how we can help people consider evidence about vaccines in a more open-minded way and to test other strategies for communicating information that might prove to be more effective.”
Here at Vaccines Today, we have a Facts section which we hope will answer questions that readers may have. But it seems, from Nyhan’s research, that pushing these on the general public – or debunking myths through posters and leaflets – is worse than useless.
The studies show that the instinctive expectation that providing information will ‘fix’ inaccurate beliefs and lead to healthy behaviours is…well, a myth!
As we heard from a risk communication expert earlier this year, we make choices about our health based on a wide range of things – including facts, emotions and much more besides.
Update: Here’s a new video interview we recorded with Dr Jason Reifler, Dr Brendan Nyhan’s co-author