Do flu experiments put whole world at risk?

It sounds like the stuff of movies: deadly viruses, manipulated in the lab to be more contagious.

But it’s real.

A handful of labs around the world are pursuing what’s known as “gain-of-function” research on bird flu viruses that are among the deadliest on the planet. In nature, people almost never catch those flu strains from each other, only through contact with infected birds. But some scientists are creating strains that can pass from person to person.