Research explains public resistance to vaccination

Research explains public resistance to vaccination
Social imitation dynamics of vaccination can exhibit hysteresis. This figure illustrates a hysteresis loop in relation to outbreaks of measles and other childhood diseases in Europe and North America. Credit: Feng Fu and Xingru Chen.

Why is it so challenging to increase the number of people who get vaccinated? How does popular resistance to vaccination remain strong even as preventable diseases make a comeback?

A new study from Dartmouth College shows that past problems with vaccines can cause a phenomenon known as hysteresis, creating a negative history that stiffens public resolve against vaccination. The finding explains why it is so hard to increase uptake even when overwhelming evidence indicates that vaccines are safe and beneficial.

A hysteresis loop causes the impact of a force to be observed even after the force itself has been eliminated. It's why unemployment rates can sometimes remain high in a recovering economy. It's why physical objects resist returning to their original state after being acted on by an outside force. And, according to the Dartmouth research, it's why the public resists vaccination campaigns for ailments like the common flu.

"Given all the benefits of vaccination, it's been a struggle to understand why vaccination rates can remain stubbornly low," said Feng Fu, an assistant professor of mathematics at Dartmouth College. "History matters, and we now know that hysteresis is part of the answer."

The research, published in the journal Proceedings of the Royal Society B, is the first study to demonstrate that hysteresis can impact public health.

"Once people question the safety or effectiveness of a , it can be very difficult to get them to move beyond those negative associations. Hysteresis is a powerful force that is difficult to break at a societal level," said Fu, who led the research team.

Low vaccine compliance is a public health issue that can cause the loss of "herd immunity" and lead to the spread of infectious diseases. In parts of Europe and North America, childhood diseases like measles, mumps and pertussis have returned as a result of insufficient vaccination coverage.

Previous studies have combined behavior models with epidemiology to understand the challenge of voluntary vaccination, but have been unable to completely explain the persistence of low vaccine compliance. The Dartmouth research specifically studies how past problems associated with vaccinations can impact present and future vaccination decisions.

"This study shows why it is so hard to reverse low or declining vaccine levels," said Xingru Chen, a graduate student at Dartmouth and the first author of the research paper. "The sheer force of factual, logical arguments around public health issues is just not enough to overcome hysteresis and human behavior."

According to the research, the hysteresis loop can be caused by questions related to the risk and effectiveness of vaccines. Negative experiences or perceptions related to vaccination impact the trend of uptake over time—known to the researchers as a "vaccination trajectory" that gets stuck in the hysteresis loop.

Hysteresis prevents an increase in vaccination levels even after the negative objections have been cleared, making society increasingly vulnerable to disease outbreaks.

"When it comes to vaccination levels, the past predicts the future. Unfortunately, this means that a lot of people are going to needlessly suffer unless we find a way to break the negative impact of the hysteresis loop," said Fu.

The study refers to the example of whole-cell pertussis vaccine in England and Wales in the period from 1978 through 1992. It took that 15-year span for uptake of the "whooping cough" vaccine to recover from 30 percent to 91 percent. According to the research team, such a recovery should only take about a year under ideal circumstances.

The research also notes the slow increase in measles vaccination in the face of resurgent outbreaks. In some countries, like France, measles has become an endemic disease despite the availability of an effective vaccine.

According to the study: "The coverage of measles vaccination has only gradually climbed up, but still remains insufficient, for more than a decade following the infamous MMR vaccination and autism controversy."

"Vaccination levels in a population can drop quickly, but, because of hysteresis, the recovery in that same population can take many years," said Chen.

For the common flu, the study suggests that a would have to have an effectiveness of above 50 percent in order to achieve high levels of vaccination, a difficult level to reach because of the speed with which the illness mutates.

By identifying the hysteresis effect in vaccination, the research team hopes that officials can design campaigns that increase voluntary vaccination rates, particularly by promoting vaccination as an altruistic behavior that is desired by moral and social norms.

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HPV vaccination uptake increasing, but still too low

More information: Imperfect vaccine and hysteresis, Proceedings of the Royal Society B, rspb.royalsocietypublishing.or … .1098/rspb.2018.2406
Provided by Dartmouth College
Citation: Research explains public resistance to vaccination (2019, January 9) retrieved 26 May 2019 from
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Jan 09, 2019
For the common flu, the study suggests that a vaccine would have to have an effectiveness of above 50 percent in order to achieve high levels of vaccination, a difficult level to reach because of the speed with which the illness mutates.

And yet, we try to force people to take influenza vaccines though we know that influenza vaccination is generally ineffective. Some hospitals punish staff who refuse vaccination by either firing those staff or making them wear masks at all times during work.

One problem is that we don't differentiate between vaccines which provide a high level of immunity to very dangerous infections such as measles, pertussis, diphtheria, etc. and generally ineffective vaccines such as influenza.

Another perceived problem is that we hit children with vaccinations with multiple agents in a single shot and give multiple vaccinations in a short time frame which makes evaluations of safety and effectiveness difficult to determine.

Jan 09, 2019
The problem is indeed a public health problem. But it isn't with vaccines. It's with psychotic conspiracy theories. This is a pervasive and pernicious problem and it needs to be addressed, but until equally pervasive and pernicious political forces can be stopped from using it it will not be.

Jan 09, 2019
One problem is the "wisdom of the crowd."

The crowd sees an industry which is focused on increasing volume of product consumed, without regard to efficacy or cost/benefit. For example: The flu vaccine, which is largely ineffective, is urged upon the crowd because "it can't hurt." But it doesn't help much either, and it does kill people.

The crowd remembers measles and chicken pox as unpleasant but rarely debilitating, yet these illnesses are lumped in with pertusis and diptheria. Why?

The crowd suspects there is an environmental cause for the increase in autism-like behaviors and extreme allergies. It suspects that repeated insults, i.e., vaccinations, to the immune systems of very young children may result in immunological reactions that are subtly damaging developing brains and endocrine systems. Remember DES?

Jan 10, 2019
The anti-vaccine "hysteria" is one part of a global campaign against all the sciences & arts. Only in the last century, under the repetitious propaganda by reactionaries, that scientists stopped considering themselves as artists. The scapegoat of the Arts being a safe target for cowardly fascists.

The lie that the influenza vaccines are unreliable is a pernicious effort to "poison the well". I know when I get the shots, I do not get the flu.

I know all too well, if I miss getting the vaccine, that I will have a severe case of the flu. Leaving me with months of chronic bronchitis.

Are the flu shots 100% effective for 100% of the people? Of course not. All our biologies have unique features. We will react differently to the same medicine.

This is an example of statistical probabilities. If only 80% of the pop get immunized? That improves the odds that the refusniks won't get sick.

When they do get sick? Increase the odds of their dying. Tradeoffs.

Jan 10, 2019
? Why can't we force people to buy this product? ?

Jan 10, 2019
? Why can't we force people to buy this product?
Because it's a terrible product!
-You give no guarantee that it will work
-You don't study whether it causes cancer
-You don't know if it affects fertility
-You don't know if it might cause genetic changes
-You DO know that some people will be harmed (some even killed) by your product, but you don't know which people are more likely to be harmed nor why
-You spend so much money lobbying that you got Congress to pass a law protecting you from liability for harm your product may cause

And you still wonder why people choose to resist your "wonderful product"???

Jan 11, 2019
well annoyingmousie or should I use one of your professional aliases of ignorant quack
or saudi trollbot
or lunatic montebank
or putin's stooge?

I don't know if you are even human. Your willingness to sacrifice the lives of so many Humans?

Leaves me thinking you are just an Artificial Stupid. An agitprop engine coded by malicious programmers to disseminate mythinformation & disrupt Public discourse of important issues.

Jan 13, 2019
Why is it so challenging? Maybe because science writers do things like put a big graph at the front of an article and then forget to label the x axis...

Jan 13, 2019
Vaccine denialists are child killers and should be burned alive.

@dogbert, you, specifically, should die in an excruciating way. @Anonym, if I meet you, I will use whatever means I have available to end your life.

@Anonym142395c, I'm too busy for you. Kill yourself, you fucking monster.

Jan 14, 2019
What's amazing is that autism is still linked in peoples' minds with vaccines after the guy who started it all had his license to practice medicine revoked, after his paper in Lancet (the premier medical scientific journal of record in the UK, where he worked) was was withdrawn after the editors were presented with evidence his research was deliberately falsified. Yes, really. The actual medical records do not agree with the report of them in his paper in Lancet.

This fraudster and liar has killed half a million children. So far.

Jan 14, 2019
Incidentally this criminal's name is Andrew Wakefield. He's moved to Texas (big surprise there, the home of nutjobs) to avoid prosecution and British lawsuits for wrongful death. He best hope no one whose child has died gets a gun and comes to one of his lying lectures. (They do that in Texas too.)

Jan 14, 2019
Why is it so challenging? Maybe because science writers do things like put a big graph at the front of an article and then forget to label the x axis...
Speaking of challenging, perhaps you could click on the image and find the label on the X axis.

Jan 14, 2019
So how does one go about shortening the hysteresis loop?
If people had minimal education they wouldn't have fallen for this BS in the first place (or at the very least they would have understood the counterarguments in short order and reverted their erroneous decision)

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