Large spikes in handgun acquisitions seen in aftermath of mass shootings

Large increases in handgun acquisitions occurred in California immediately following the mass shootings in Newtown, Ct., in 2012 and San Bernardino, Calif., in 2015, a study found, creating potential for harms from firearms beyond the incidents themselves.

Using reports of firearm transactions from California's Dealer Record of Sale system between 2007 and 2016, researchers at Stanford University analyzed acquisition patterns after the two mass shootings to create a seasonal autoregressive integrated moving-average model adjusted for higher-than-expected gun sales based on trends, seasonality, and changes in variance over time.

The findings were published online May 2 by Annals of Internal Medicine.

Overall, the number of handguns acquired in California increased sharply in the first 12 weeks following the Newtown and San Bernardino mass shootings. In the six weeks after each incident, there were 25,705 (95% prediction interval, 17,411 to 32,788) and 27,413 (prediction interval, 15,188 to 37,734) excess acquisitions, respectively, representing increases of 53% (95% CI, 30% to 80%) and 41% (CI, 19% to 68%) over expected volume.

The acquisition response seemed to be disproportionately large among women, the study found. Acquisition rates were 75% higher (3 excess acquisitions per 10,000 residents per week) than expected among women and 48% higher (16 excess acquisitions per 10,000 residents per week) among men in the six weeks after the Newtown shootings, and they were 50% higher (3 excess acquisitions per 10,000 residents per week) than expected among women and 38% higher (16 excess acquisitions per 10,000 residents per week) among men in the six weeks after San Bernardino shootings. Researchers added that men continued to acquire handguns at a much higher rate than women throughout the observation periods.

Acquisition rates among white persons were 62% higher than expected after the Newtown shootings and 47% higher after the San Bernardino shootings (18 excess acquisitions per 10,000 residents per week for both). Acquisition rates among Hispanic persons were 43% higher (3 excess acquisitions per 10,000 residents per week) than expected after the Newtown shootings and 50% higher after the San Bernardino shootings (5 excess acquisitions per 10,000 residents per week). Acquisition increases among black persons after both mass shootings were relatively small and not statistically significant.

In the six weeks after the Newtown shootings, the number of acquisitions by first acquirers was 72% higher than expected (14,560 excess acquisitions), compared with 35% higher than expected (10,269 excess acquisitions) among repeat acquirers. In the six weeks after the San Bernardino shootings, acquisitions by first acquirers were 52% higher than expected (13,950 excess acquisitions) compared with 29% higher (11,816 excess acquisitions) among repeat acquirers.

The authors noted that the spikes were short-lived and accounted for fewer than 10% of annual handgun acquisitions statewide but expressed concern about whether repeated shocks of mass shootings could lead to substantial increases in the prevalence of firearm ownership, which could in turn increase the long-term risk for firearm-related morbidity and mortality.

An editorial noted that mass shootings have a larger effect on people becoming first-time handgun owners than on the number of handguns a person owns. Because gun ownership is linked with higher risk for suicide and domestic homicide, mass shootings could indirectly elevate firearm mortality well beyond the deaths that occur in such shootings, a fact compounded as political responses spur right-to-carry laws that make gun ownership more prevalent, the editorialists said.

“Telling people that their fears of mass shootings and their urge to defend themselves against such shootings are irrational is unlikely to be effective,” the editorial concludes. “Keys to a productive path forward will be tracking and publicizing the tragic shootings that occur when persons who legally possess firearms in public places are the shooters, juxtaposing the frequency of these events versus the number of times civilians use guns effectively to thwart attempts at mass shooting, and gaining the trust of gun owners through cultural competence.”