After every mass shooting, Americans ask themselves how it could have been prevented. Vigils are held; flowers are left at the scene. After Sunday's shooting at a gay nightclub in Orlando, the mother of one of the victims tearfully spoke of her son's accomplishments and pleaded with the nation to "try to get rid of the hatred and the violence."

Even the leading U.S. presidential candidates weighed in. Presumptive Republican nominee Donald Trump again called for a temporary ban on Muslim immigration. "The only reason the killer was in America in the first place is because we allowed his family to come here," Trump told supporters.

Hillary Clinton, the presumptive Democratic nominee, called for stricter gun control measures. "I believe weapons of war have no place on our streets," she said. The weapon used in the mass shooting was a semi-automatic rifle.

Missing in the expressions of sorrow and shock and calls for peace is a plan to end gun violence.

‘Public health measure’

Medical doctors, like Georges Benjamin, executive director of the American Public Health Association, look at gun violence through a different lens. "I see the whole issue of people dying prematurely from firearms as a public health measure," Benjamin said.

Law enforcement officials gather outside the Pulse
Law enforcement officials gather outside the Pulse nightclub, the scene of Sunday's mass shooting in Orlando, Florida, June 15, 2016.

The American Medical Association, or AMA, the largest association of physicians in the U.S., issued a statement saying, "The shooting in Orlando is a horrific reminder of the public health crisis of gun violence rippling across the United States."

The website of the Centers for Disease Control and Prevention, the agency charged with guarding the nation's public health, has nothing on gun violence or gun safety. CDC director Tom Frieden does not mention gun safety in his speeches or interviews.

When VOA asked Frieden for a comment after the Orlando shooting, the CDC sent an email saying, "Our thoughts are with the families and the community who mourn the loss of loved ones as a result of tragic shootings like those this past weekend. Every year there are more than 33,000 firearm-related deaths and 84,000 injuries in America. Research can help us understand why deaths and injuries from firearms happen and evaluate interventions to reduce or prevent them. The president has asked Congress each year for $10 million to build the evidence base of what works to improve gun safety."

Government studies

The issue of gun violence has turned political.

Congress has refused to fund any government study on gun violence since 1996 after the National Rifle Association accused the CDC of lobbying for gun control. Researchers say the lack of funding helps perpetuate the violence. The AMA has now pledged to actively lobby Congress to lift that ban.

Police conduct a manhunt after gunmen opened fire
FILE - Police conduct a manhunt during the mass shooting in San Bernardino, California, Dec. 2, 2015.

"We certainly don't have as much research on gun violence prevention relative to the size of the problem," said professor Jon Vernick at the Johns Hopkins University.   

The CDC keeps tabs on the causes of death, but there is no research on what prompts mass killings or other gun violence. Benjamin says it flies in the face of scientific research. Public health experts point to studies about car accidents and how this led to seat belts and other measures that have drastically reduced automobile deaths.

"What we do when we have most problems is we gather the data to find out what's happening,” Benjamin said. “What are the issues? What are the problems? And then we sit around a table with a multidisciplinary team and figure out what some of the reasonable solutions are. We put them in place and we test them and see if they work. And we do that until we dramatically, over time, bring down the health risk.”