I don't see why there should be any contra indication to massage. Why would it be an issue to the client to have the nasty toxins in the shot circulating faster through their system. The whole point of the vaccination is to put the crap in the body!
Only thing to watch out for is if they have side effects to the vaccination such as mild soreness, redness, swelling where the shot was given, fever, aches. They will already be dumb so when you notice don't take it as a side effect!