Vickers was admitted to the hospital Wednesday night after complaining of chest pains. He was diagnosed with blood clots in his chest and leg.
The clots were dissolved by medication, but the 26-year-old driver said on his Web site he's tired. He will meet with doctors in Charlotte this week to continue his recovery.
Casey Mears drove for Vickers in the Autism Speaks 400 at Dover International Speedway Sunday and finished 22nd.
Vickers dropped seven spots in the series standings to 27th, hurting any hopes he had to qualify for the season-ending Chase for the Championship.
The all-star race, however, is a non-points race for race winners from the past two seasons, as well as former all-star and series champions. Vickers won last year and is qualified to compete in the main event; Mears doesn't meet any of the all-star qualifications.
Red Bull Racing can ask series director John Darby for an exemption to allow Mears to replace Vickers, NASCAR spokesman Ramsey Poston said. Darby has the authority to approve a driver switch that could keep the team in the all-star race. As of Sunday's race, the team hasn't asked for the exception because it wants to check on Vickers' health first.
PONIES AT DAYTONA: The new Car of Tomorrow for the Nationwide Series will get its final shakedown Tuesday and Wednesday at Daytona International Speedway.
Like current cars in the Sprint Cup Series, the new Nationwide car is wider and taller to promote safety.
Some will be a departure from the cars used in the Sprint Cup Series.
The Subway Jalapeno 250 on July 2 at Daytona International Speedway will be the first race for the new fleet of pony cars -- Mustangs for Ford and Challengers for Dodge. Toyota (Camry) and Chevrolet (Impala) will stick with their core brands.
Among the drivers scheduled to test at Daytona are Joey Logano, Carl Edwards, Kyle Busch, Kevin Harvick, Paul Menard, Clint Bowyer, Reed Sorenson, Jason Leffler and Jason Keller.