How many variants of the coronavirus are there?
There are many circulating around the world, but health experts are primarily concerned with the emergence of three.
As a virus infects people, it can mutate as it makes copies of itself. Some mutations can be harmful to a virus, causing it to die out. Others can offer an advantage and help it spread.
“Not every mutation is created equal,” said Mary Petrone, who studies infectious diseases at Yale University. “The virus is going to get lucky now and again.”
Monitoring variants is important because of the possibility that they could make vaccines and treatments less effective, or change the way they infect people.