Shiffrin thus misses, among other things, Tuesday's giant slalom in Lienz in Austria, where she would have faced Sara Hector.
The Swede took her only second World Cup victory in the giant slalom in Courchevel just before Christmas.
“I just wanted to say that I feel good, but unfortunately I have tested positive for covid.
I follow the rules and have isolated myself and I will miss Lienz ", writes Shiffrin on Twitter and adds:
"See you next year".