When you hear the word "contagious," you likely think of the typical cold or flu that makes its way around your workplace during the winter months, but a study done earlier this year by Arizona State University and Northeastern Illinois University researchers came to the terrifying conclusion that school shootings and mass killings may be contagious. The researchers found that mass killings and school shootings are most likely to happen in short clusters of time, suggesting that, much like diseases, these events spread and possibly do so under the influence of widespread media coverage.

The study examined 176 mass shootings in the U.S. from 2006 to 2011 and 220 school shootings that took place between 1997 and 2013. The results showed that mass shootings were more likely to take place if there was another shooting that received national media coverage in the past 13 days. This suggests that mass shootings cluster together much like suicides, and media coverage may plant the seeds of these events in the minds of individuals already at-risk of committing such acts.

"People had suspected for a long time that mass killings were contagious," Sherry Towers, the study's lead author, told The Huffington Post. "Our study was the first to use to use a contagion model to quantify how much contagion there actually is in these kinds of tragedies." 

Despite the study's suggestion that media may be one factor that stimulates this contagion effect, the media seems to be more like a double-edged sword - for example, after nine people were shot and killed at a predominantly black church in Charleston, S.C., back in June, the killer was located due to a tip obtained from a witness that noticed his distinctive features from news reports, according to Vox.

No matter what the answer may be, Congress currently has a federal ban on research dollars that go towards gun violence, making it very hard to examine the issue further. Until this restriction loosens, researchers will likely have a difficult time discerning the connection between mass killings, school shootings and national media coverage.

The findings were published in the July. 2 issue of PLOS ONE.