Scientists are still piecing together how COVID-19 spreads from animals to humans.
Now, researchers at Ohio State University are taking a closer look at how it's possible for the virus to jump from humans back to animals.
We've already seen it happen.
Mink in Denmark that got infected after coming into contact with humans developed variations that can jump back to humans.
Researchers say the virus does not need to jump to another species to evolve, but it is more likely to happen.
Researchers say right now only Mink are playing a significant role in human infection.
It is possible for regular household pets to infect humans and vice versa, but so far we've seen very low rates of that happening.