More than 40 percent of a sample of U.S. adults believe the myth that flu vaccines can give you the flu, and even correcting that misconception might not convince them to get the vaccine, a new survey suggests.

“It is absolutely biologically impossible to get the flu from the vaccine,” said Dr. Gregory A. Poland, a professor of medicine at the Mayo Clinic in Rochester, Minnesota, who studies the immunogenetics of vaccine response.

He was not involved with the new study.

It seems logical that dispelling this myth would lead to more people getting the shot, but it may not work that way in real life, Poland told Reuters Health by phone.

“Things that seem logical and intuitive can have perverse effects that we don’t always understand or expect,” he said.

The new results show that teaching patients about the safety and efficacy of the vaccine shouldn’t be ‘one size fits all,’ he said.

“I think we have to move toward a model where I as a physician have to change my style of educating based on my listening and understanding what your educational needs are,” he said.

In an online survey in 2012, 1,000 U.S. adults were asked how concerned they were about side effects from the influenza vaccine.

A quarter of people said they were extremely or very concerned.

Next, the 1,000 respondents were randomly divided into three groups. One group got information from the Centers for Disease Control and Prevention (CDC) website on the safety of the flu vaccine. The second group received information from the CDC on the danger of the flu itself. The third group did not have any information.

Then the respondents answered questions about whether or not one can get the flu from the vaccine, their belief in the safety of the vaccine, and their intent to get a flu shot in the coming year.

More than 40 percent of people believed the statement “the flu vaccine can give you the flu” was at least somewhat accurate, and four percent believed the vaccine was not at all safe, according to results in Vaccine.

In the group that read CDC information on the safety of the vaccine, fewer people believed it could give you the flu.

But the group that read about the dangers of the flu still had misperceptions about the flu vaccine, the authors found.

Overall, about a third of participants said they were very unlikely to get a flu shot in the coming year – and neither information source seemed to affect that intention.

But when the researchers only considered people who were most concerned about side effects, reading about the safety of the vaccine actually decreased their likelihood of getting it.

“When we defend our attitudes or beliefs against challenge we can sometimes back ourselves further into those beliefs,” said the lead author of the new study, Brendan Nyhan.

Nyhan, an assistant professor of government at Dartmouth College in Hanover, New Hampshire, said the study did not look at why certain people would react paradoxically when flu shot myths are debunked.

“Neither intervention had a significant effect on intention to vaccinate, and we probably overestimate how likely messaging is to change people minds about vaccines,” Nyhan told Reuters Health by phone.

Reinforcing the message that the flu vaccine does not cause the flu is unlikely to increase vaccinations, and may even be counterproductive, he said.

“I think it’s a matter of focus,” Nyhan said. “When someone asks will the flu vaccine give me the flu, of course you should say no,” but leading with myth-debunking may not influence more people to get the shot, he said.

Whereas drugs are rigorously tested and proven effective before they hit the market, public health messaging is often not based on evidence, Nyhan said.

“People think of public health messaging as a silver bullet, but people’s minds are a lot harder to change than that,” he said.

This year, with the seasonal flu vaccine making headlines for potentially being less effective than previous years, is a particularly interesting time to study how we talk about the vaccine, Poland said.

“Most of the flu vaccine this year contains protection from about four different strains of the virus,” Poland said. “All four will circulate this year, but one of those four strains has mutated.”

In a few months we will know how much the current vaccine protects from that fourth strain, but even with that caveat, some protection is better than none, he said.

“I would definitely have people get the flu vaccine this year,” he said.

The flu still kills up to 30,000 Americans each year, primarily the elderly, the very young or those with chronic health problems, he noted.