The 7-time Cup Series champ says the situation is "extremely disappointing," but that his first priority is "the health and safety of my loved ones and my teammates."

Jimmie is reportedly asymptomatic, but was tested Friday morning after learning his wife tested positive. NASCAR says he won't be eligible to return until he has 2 negative tests at least 24 hours apart, is cleared by his own physician, and of course ... remains symptom-free.

Johnson was set to start Sunday's race in 4th position, and was gunning for his 5th win at the Brickyard ... matching his former teammate, Jeff Gordon.

Jimmie missing the race might also make it difficult for him to make the cut for the NASCAR playoffs -- and a shot at one last title run -- especially if he misses more.

The late scratch also stops Johnson's amazing consecutive race streak -- he's started every single Cup Series race since 2002's Daytona 500.