IDC New York

IDC New York

November 21, 2015
3 min read

Misinformation, false perception of risk contribute to vaccine hesitancy

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NEW YORK — Barriers to modifying vaccine hesitancy include misguided thinking, misinformation and a false perception of fear based on anecdotal thinking, according to a presentation at the 2015 Infectious Diseases in Children Symposium.

Altering anti-vaccination attitudes requires reeducating vaccine-refusing parents and caregivers to change how they think about the relatively low risks related to vaccination, in comparison to the potentially fatal risks associated with not vaccinating, according to Gary S. Marshall, MD, chief of pediatric infectious diseases at the University of Louisville School of Medicine.

Gary Marshall

Gary S. Marshall

“Parents are worried about vaccinating their children,” Marshall said. “We know this from our practices, and we know this from survey studies that have been done. The good news is that 90% of parents still think that vaccines are a good way to protect their children, but, as of 2010, half of parents were still worried about serious adverse events, and a quarter of parents still believed that vaccines cause autism.”

According to Marshall, 54% of pediatricians have encountered complete vaccine refusal, while 85% have encountered at least some type of vaccine refusal.

“If you ask pediatricians in practice, the vast majority find parents every single week that either don’t want vaccines or want them according to their own schedules, or refuse some part of the vaccine schedule,” Marshall said.

He noted that according to recent research, 69.3% of children aged older than 9 years are on a routine vaccination schedule; however, 25.4% are currently on an alternative schedule and 5.3% have no known vaccination schedule status.

“Most alarmingly, when pediatricians were asked what they do if they have parents who want to ‘spread the vaccines out’ – 37% responded that they often or always acquiesced to the parent’s wishes,” Marshall said. “And only a minority of pediatricians said ‘sorry, if you don’t want the vaccines, you’re going to have to find another provider.’”

Root causes 

Marshall stated that vaccine-hesitant attitudes develop as a result of many compounding influential factors, such as shifting paradigms, actual adverse events, the ubiquity of misinformation, confusion and poor communication.

Misinformation based on faulty science can be harnessed by anti-vaccination proponents and exacerbate the perception of danger among vaccine-hesitant parents, according to Marshall.

"The fear of the vaccines leads directly to public harm,” Marshall said. “We don’t have to look much further than back in the 1980s, when a case series claimed that the whole-cell pertussis vaccine causes encephalopathy. It wasn’t very scientific, and people in England became afraid to give their kids vaccines, and the consequences were basically that 400 babies coughed themselves to death – for only one reason, because their parents were afraid to give them the vaccine."

However, it is important to recognize the truth that vaccines are not completely safe, Marshall noted, although the danger associated with vaccines must be put into proper perspective.

“Vaccines are not 100% safe,” Marshall said. “Some of the known side effects of vaccines are very rare, although in some cases they are not that rare.

“The rhesus rotavirus vaccine caused intussusception in 1 in 11,000 cases. That is actually rarer than just getting intussusception naturally, which is about 1 in 2,000, but it is a serious enough side effect that it killed the vaccine.”

According to Marshall, the risk-benefit ratio of vaccines is a key component to changing the minds of vaccine-hesitant parents. The annual amount of prevented hospitalizations associated with rotavirus vaccine is about 53,444, vs. 45 hospitalizations caused by the vaccine – a ratio of 1093 to 1. Similarly, the annual amount of deaths prevented by rotavirus vaccine is 14, compared to 0.2 annual deaths associated with the vaccine – a ratio of 71 to 1.

Marshall noted that there are different types of parents and caregivers when it comes to attitudes toward vaccines, and it is important to understand which type you are dealing with while having the vaccine conversation.

“There are the immunization advocates, who just do what you say, there are the parents who are going to go along after a little bit of discussion, there are those who are going to require a lot of information and then there is a very small minority who are absolutely unreachable,” Marshall said. “That’s the 5% who you will not convince, they are not who we have to work on – if we can get 95% immunized, we’ll be above the herd immunity threshold for almost all of the diseases.”

A fundamental shift is required in vaccine-hesitant parents in order to get vaccination rates to safe levels for the community at large, according to Marshall.

“I would argue that we have to get down to these root causes and we have to affect change.” Marshall concluded. “The perception of risk needs to be changed to risk-benefit analysis.” – David Costill

Marshall GS. “Roots of Vaccine Hesitancy” Presented at: IDC NY 2015; November 21-22, 2015; New York.

Disclosure: Marshall is a clinical trial investigator and consultant for GlaxoSmithKline, Merck, Pfizer and Novartis.