That biological stability lasts for a while. By the time they hit their teenage years and their young twenties, many young people certainly believe they’re invincible—and, from a disease standpoint, they mostly are. Considering just the pathological causes of death, the annual mortality rate among those aged 15 to 24 is less than about 18 deaths for every 100,000 Americans. (Unintentional injuries—from car accidents to falls and accidental poisonings—account for 28.5 deaths per 100,000 people in this age group.)

And then there are gun deaths. In 2015, 143 kids between ages five and 24 died as the result of a firearm discharging accidentally. Another 2,601 kids in this age group—It’s okay if I call them kids, right?—took their own lives with a firearm. And another 4,330 were shot dead intentionally.

In the year 2015, there were 35,905 deaths of Americans between the ages of five and 24 from all causes put together. One in five of these young deaths—that’s 7,074 burials in all—were due to firearms. One in five.

Cancer, by comparison, claimed 2,334 lives in this age group. Pneumonia and the flu: 267. Diabetes: 219. Indeed, there were nearly 2,800 fewer deaths in this precious young cohort from drugs than there were from guns. (I, for one, didn’t believe it at first—and had to do the calculation several times to be sure.)

Guns in this country have unleashed a lethal infection that is stealing young lives in every county, city, and town. To call it less than a raging epidemic is to fool ourselves. To pretend it will go away on its own is to con ourselves. To do nothing to try and stop it is to betray ourselves and every generation to come.

It’s hard for many of us to accept, but we are culpable in spreading one of the worst child-killing diseases there is.

This essay appears in today’s edition of the Fortune Brainstorm Health Daily. Get it delivered straight to your inbox.