My dachshund ( max is 15 now) has had allergic reaction to his vaccines since he was 8 weeks old......has to get a shot before the shot. The first time he reacted he was just a puppy, muzzle and eyes swelled, labored breathing, got him back to the vet just in time. The symptoms appeared within one hour of the vaccine.
Yea that's a very severe reaction. I take allergy shots myself and they make you stay 20 mimutes just to make sure you don't shock on them.