By Andrew M. Seaman
NEW YORK (Reuters Health) - Education campaigns that aim to inform people about the benefits of vaccines do little to increase the intent of parents to vaccinate their future children, according to a new study.
Furthermore, researchers found that among a group of parents who were least likely to vaccinate their future children, some education campaigns actually added to their reservations.
The study's lead author told Reuters Health that the research is an extension of his work in political science that found it is difficult to correct people's misinformation.
"We found political misinformation is often very difficult to correct and giving people the correct information can backfire," said Brendan Nyhan, a political scientist at Dartmouth College in Hanover, New Hampshire.
"We were interested in seeing if the messages public health agencies were putting out were effective," he said.
Specifically, Nyhan and his colleagues examined public health campaigns about the measles-mumps-rubella (MMR) vaccine.
Although national U.S. MMR vaccination rates are high, the researchers write in Pediatrics that there are states where the rate dips below 90 percent, which is a commonly used threshold for so-call herd immunity. Herd immunity is the point where high vaccination rates within a population may also offer protection to the unvaccinated.
They also write that maintaining high levels of MMR vaccination is important because of the increasing number of measles cases reported in the U.S. and recent outbreaks in the UK. Measles is a highly contagious respiratory disease that can lead to death.
Another study published by Centers for Disease Control and Prevention (CDC) researchers in the same journal found that vaccinating U.S. kids born in 2009 according to the routine immunization schedule will save about $70 billion and prevent over 40,000 early deaths and over 20 million cases of disease.
For their new study, Nyhan and his colleagues used data from nationally representative surveys conducted in June and July 2011 of 1,759 parents who were at least 18 years old.
During one survey, parents were asked for general information about the health of their children and about their attitudes toward vaccination.
The parents were then randomly assigned to receive one of five messages an average of 12 days later and surveyed again after that.
The first message or campaign used information from the CDC to correct misinformation that the MMR vaccine causes autism, a belief that has been disproven.
The second and third campaigns also used materials from the CDC to present information on the risk of the preventable diseases or a story about one woman's experience with her son being hospitalized with measles.
The fourth campaign consisted of pictures of children who had each disease.
Another group of parents was asked to read information about the cost and benefits of bird feeding to act as a comparison group.
During the second survey, there was no significant increase in parents' intents to vaccinate their future children, but those who received the CDC information debunking the link between the MMR vaccine and autism had fewer misperceptions about that topic.
However, among the one third of people who were least likely to vaccinate any future children they may have, getting those same materials was linked to an even lower likelihood that they would vaccinate.
That strengthening of convictions among the least likely to vaccinate may be due to those people coming up with other arguments to support their beliefs, the researchers write.
"We can't look inside their head," Nyhan said, adding that it's a theoretical interpretation but consistent with other research.
The researchers also found the campaigns aimed at stressing the dangers of the preventable diseases only increased parents' misperceptions.
"We need to test public health messages of all sorts to see if they're effective - especially with some sub-populations that may be resistant to some public health messages," Nyhan said.
Dr. Mary Healy said it's also important that there not be just one mass-market public health campaign addressing vaccines.
"This is very important research, because any public health campaign we release we have to make sure they're effective," said Healy, from the Center for Vaccine Awareness and Research at Texas Children's Hospital in Houston. She was not involved with the new research.
Healy said the study also emphasizes the role of the relationship between the parent and healthcare provider in clearing up misinformation.
"If I had any message, you need to talk to your healthcare provider and bring your worries to your healthcare provider," she said.
SOURCES: http://bit.ly/1n2APr0 and http://bit.ly/1n2AS6l Pediatrics, online March 3, 2014.