With all the controversy about gain-of-function research and all the concerns about how dangerous it is, you might think that scientists have stopped doing that kind of work.

Well, no.

In the latest news, a team of scientists in Canada and the U.S. report that they have re-created the 1918 influenza virus and used it to infect macaques. Let’s be clear here: the 1918 flu vanished from the Earth, long ago. It’s simply not a threat, or it least it wasn’t, until someone figured out a way to bring it back.

Why would anyone do this? I’ll get to that, but first a little background.

The 1918 flu pandemic was the worst plague since the Black Death, which occured in the mid-14^th century. During World War I, a new flu virus swept the planet, killing upwards of 50 million people. It probably infected a third of the entire world population at the time.