As media attention to the measles outbreak in California continues to grow and prominent politicians weigh in with conflicting messages on requiring vaccines, health policy scholars and political scientists warn of the dangerous consequences that politicization can have on public support for vaccination. And they do so for good reason.

This is not the first time that a vaccine has been politicized in media in recent years. In a new article, we examine two recent health-related controversies: the 2009 dust-up over mammography screening guidelines and the 2006-2007 debate over whether to require girls to get the HPV vaccine. The key lesson regarding vaccines is this: the more the news media devoted attention to the political controversy, the less the public supported vaccination.

Neither mammography nor the HPV vaccine started out as controversial.  But once the news media highlighted political sources or partisan conflict about these issues, future news coverage continued to reflect this politicization — even as news coverage of these issues tapered off.  This fits with journalistic norms of covering conflict and controversy.

For example, after the controversy about the HPV vaccine, states moved on to less controversial measures – like educating the public or providing insurance coverage of the vaccine. But media coverage still mentioned the earlier political firestorm. In short, once the issue gained a political valence, news coverage continued to emphasize the controversy.

In fact, these controversies routinely reappear in media coverage about other issues entirely. Media coverage of the measles vaccine controversy referred back to the 2011 argument between Republican presidential candidates Rick Perry and Michelle Bachmann over Perry’s decision to mandate the HPV vaccine in Texas.

Continuing coverage of the controversy surrounding vaccines may have unfortunate consequences. In our study, we found that politicized media coverage was associated with lower support for requiring the HPV vaccine.

This was evident in the relationship between the attitudes of survey respondents and the media coverage in their states.  It was also evident in an experiment we included in this survey.  People were exposed to brief news excerpts discussing the debate over requiring the HPV vaccine.  Some people saw excerpts highlighting conflict among politicians, some saw excerpts highlighting conflict among doctors, and some saw excerpts that mentioned both types of conflict.

For those people who were less likely to have previously encountered news stories about the HPV vaccine controversy, reading about political conflict decreased support for vaccines in general.  It also decreased trust in doctors. This suggests a very troubling implication: media coverage of the controversy about the measles vaccine could actually affect the general public beyond the very small “anti-vax” community.

But our research also suggests a way for news coverage to avoid this.  We found that news coverage that did not emphasize conflict was associated with increased support for both the HPV vaccine and immunization programs generally.  This shows how news media could bolster support for needed vaccinations: steer clear of the political controversy.

At this moment, there are signs that the controversy about the measles vaccine could die down.  Rand Paul and Chris Christie have backed off their controversial statements about vaccine requirements.  More and more, commentators bemoan the politicization of vaccines. And public attention to issues is often short-lived, which means citizens could easily forget political cues about vaccines, presuming that politicians stop stoking the controversy.

However, our research suggests that it is journalists who may not forget. They may continue to remind the public of this controversy for years to come, as they have done for mammography recommendations and the HPV vaccine.

Of course, perhaps coverage of the measles vaccine will prove different.  Nevertheless, politicians and journalists should realize that politicizing vaccines — and reporting on the resulting conflict — can weaken the public’s support for vaccination.

Erika Franklin Fowler is an assistant professor of government at Wesleyan University.  Sarah Gollust is an assistant professor in the School of Public Health at the University of Minnesota. Their article about vaccines is part of a special issue of The ANNALS of the American Academy of Political and Social Science.  The issue is devoted to research about the politics of science.