The centre, who underwent a scan yesterday, has been ruled out with a groin injury.
Acting Scotland boss Frank Hadden is yet to name a replacement for Andy, who has been ordered to rest.
Hadden is already without Sale flanker Jason White (broken thumb) and Worcester winger Ben Hinshelwood (back), so Glasgow's Paul Dearlove and Edinburgh's Ben MacDougall have been called up.
Newcastle lock Stuart Grimes, who has knee and shoulder injuries, has missed training but could be fit for both matches.