Mass shootings are up nearly 73% so far in 2021 in what gun violence researchers describe as a contagion effect

Three and a half months into 2021, mass shootings in the US have increased nearly 73% from the same period last year — and gun violence researchers say each new shooting is likely to spark another in a contagion effect. 

There have been 147 mass shootings in the US since New Years Day, compared to 85 such incidents between January 1 and April 16, 2020, according to data published by the Gun Violence Archive. A mass shooting is defined in the database as an incident where four or more people were shot and killed, not including the shooter.

Mass shootings in 2021 also have been deadlier than early last year. According to the Gun Violence Archive, 176 people have been killed so far this year compared to 92 fatalities during the same period in 2020.

"It is a disease, violence, and it is contagious," Dr. Gary Slutkin, former head of the World Health Organization's Intervention Development Unit, told Insider.

"One event is a risk factor for another event, just like one event of COVID is a risk factor for another event of COVID," he added.

In recent weeks, coverage of one deadly shooting often has been interrupted by breaking news of another.

On March 16, eight people, including six Asian women, were killed at several spas in metro Atlanta by a man armed with an AR-15. Two weeks later, a gunman with the same weapon killed 10 people at a Colorado grocery store.

On Thursday, another man carrying an rifle killed eight people and injured several others at a FedEx facility near Indianapolis International Airport. 

Research shows the timing of these incidents isn't likely a coincidence, Slutkin said, since the more people see violence and take it in as "normal" the more likely they are to commit violence themselves.

"We know historically there is a strong copycat phenomenon with high-profile mass shootings," Dr. Jonathan M. Metzl, Director of the Center for Medicine, Health, and Society at Vanderbilt University, Nashville, told Insider. "And so when there's one in the news it tends to spur a number of copycat events, so people feel a contagion effect. One leads to another, leads to another." 

"This is a lot of people who are on edge having the means to do something and seeing that other people are doing it," he added. 

Slutkin told Insider that while "rage shootings" have been on the rise for decades, the COVID-19 pandemic briefly interrupted the trend in 2020, making the violence of recent weeks even more jarring.

"People were not in churches, parking lots, you know, shopping stores," Slutkin said of the pandemic. "There were just less people in public places, so it's just resuming." 

Gun violence researchers want community intervention and stronger gun laws

Against the backdrop of increasing mass shootings, gun violence researchers point out little has been done to prevent the next one from happening. 

Slutkin said addressing mass shootings through gun laws relies so heavily on the cooperation of political figures that his organization, Cure Violence Global, seeks to reduce violence by embedding in communities. The organization works around the world to establish "interruption networks" of outreach workers who put an ear to the ground for discussions of violence and attempt to stop it. 

This interruption practice drops shootings and killings between 40% and 70%, Slutkin said, but nothing similar has been established for mass shootings. 

"The missing piece is really the intervention, what stops that progression within you and that spread," Slutkin said. "With COVID, it's the mask or the distancing. For this, the network for interruption, it's not there." 

According to the Gun Violence Archive, at least 12,417 people have died from gun violence so far this year in the US, and at least 6,996 of them died by suicide. Gun violence researchers say laws requiring a waiting period after purchasing a gun could cut down the number of lives lost in both mass shootings and suicide. The suspects in the Atlanta and Boulder mass shootings bought their guns within days of those attacks. 

"Obviously that cannot prevent all acts of violence or self-harm, but there is good research that shows that it does lead to reductions in both suicide and homicide by preventing some impulsive, heat-of-the-moment acts of violence," Ari Freilich, the state policy director at the Giffords Law Center, told Insider.

Metzl believes passing gun laws including background checks and bans on high-capacity magazines also will cut down on gun violence casualties. 

"It's important to remember at times like this that we have over 40,000 gun deaths a year," Metzl said. "So there are plenty of policies we can announce that will lower rates of everyday gun death. It's not so much, 'Oh, this one policy is going to stop a mass shooting,' but we can save more lives by enacting common sense policies."

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