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.
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"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 US MMR vaccination rates
are high, the researchers write in Paediatrics that there are states where the
rate dips below 90%, which is a commonly used threshold for so-call herd
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 US and recent outbreaks
in the UK. Measles is a highly contagious respiratory disease that can lead to
Another study published by Centres for Disease Control and
Prevention (CDC) researchers in the same journal found that vaccinating US kids
born in 2009 according to the routine immunisation schedule will save about $70
billion and prevent over 40 000 early deaths and over 20 million cases of
MMR vaccine and
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
vaccine cleared again
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 hospitalised 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
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
Resistance to health
"We can't look inside their head," Nyhan said,
adding that it's a theoretical interpretation but consistent with other
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 Centre 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.
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