You might have given the coronavirus to your cat

Anna Rothschild: Do we have real-world examples — maybe not from COVID-19 but from past viral infections that have jumped from humans to animals — of the viruses kind of changing as they get passed back and forth between humans and animals? Maggie Koerth: We do. Flu is actually really fascinating for this. And we know a lot of this stuff about flu because this is something researchers have been focused on studying for a very, very long time, because flu, unlike COVID-19, seems to infect agricultural animals, things like chickens and domestic ducks and pigs. So, if you look at this pig situation, and this is one of the most fascinating stories I picked up while reporting, the 2009 swine flu pandemic, is something that some of you may remember, originated on these giant pig farms in Mexico, where people were in close contact with pigs and it was getting sort of passed over from the pigs to people. At that time, when it first emerged, this particular variant of flu was not present in pigs anywhere else in the world. Today, after that pandemic has happened and people have spread it all over the planet, there is not a place on earth that farms pigs that does not have descendants of that 2009 swine flu strain in the pigs. And it is not because the pigs have been traveling all over the place.