AUSTIN (KXAN) — One year after a mass shooting at an El Paso Walmart left 23 dead, criminal justice researchers who study mass shootings have noticed a peculiar trend — there hasn’t been a mass shootings in the U.S. since the pandemic started.

As more people stay home and mass gatherings are discouraged, public shootings have gone away.

“We’ve never had anything like this,” said Dr. Jillian Peterson, the founder of The Violence Project, a nonprofit that tracks and studies mass shootings — which it considers to be shootings resulting in four or more fatalities.

Peterson listed going to school, church, work, and other large gatherings as examples of activities that have stopped or slowed significantly.

But it isn’t just that the opportunity is no longer there. Another factor is our society’s focus shifting intensely to the pandemic.

“We know that mass shootings are socially contagious, we know that they cluster, we know that perpetrators copy each other,” Peterson said.

She believes that the longer mass shootings aren’t happening, the less likely a mentally ill person is to consider one as a viable solution to dealing with their problems.

While the U.S. averaged seven mass shootings per year from 2017-19, this year’s lone mass shooting was at the end of February — before the pandemic took hold in the country.

Interestingly, the Violence Project found mass shootings also dropped off after the September 11, 2001 terrorist attacks.

The U.S. has averaged five per year from 1999-2001. Then, there was just one in all of 2002.

Additionally, Peterson’s work found that a majority of school shootings happen shortly after students return to campus, in September and October, and also in May before the end of the year.

“I think particularly this September and October is where people are keeping their eyes on things, and feeling a little anxious perhaps,” she said.

However, the big question now is what’ll happen once the pandemic is over.

While Peterson is hopeful that mass shootings will fade away after so much time is spent focused on the coronavirus, she worries that a lot of the risk factors are starting to compound.

“We know that young people are at home in sometimes abusive homes. We know that there’s increases in depression and hopelessness. We know that people are losing their jobs, that relationships are hurting,” she said. “Those are often triggers. Then we also know that gun sales have really skyrocketed since this started, which is another contributing factor.”