World Cup leader Mikaela Shiffrin said on Monday she has tested positive for the coronavirus and will miss this week’s races in Austria. “I wanted to let you all know that I’m doing well, but unfortunately I had a positive COVID test,” the American Shiffrin tweeted. “I’m following protocol and isolating, and I will miss Lienz … Thank you all for your support. I’ll see you in the new year.” The Lienz races are a giant slalom Tuesday and a slalom Wednesday, with Shiffrin winning both races in 2019. Her participation in the Zagreb slalom on January 4 as well as a giant slalom and slalom in Mari…