Here is the product insert on the vaccine.
http://www.pfizerah.com/PAHimages/co...compliance.pdf Notice: This product license is conditional.
Efficacy and/or potency of this product have not been
fully demonstrated, consultation with a veterinarian
is recommended.
That means you are being used as part of a clinical trial. At the end of the trial, they will look back at the REPORTED side effects/reactions and make a determination on it's safety.
As for it's efficacy, it can't be determined in a wide spread study like this. There are too many variables- what do you feed, how often or do you brush your dogs teeth, breed, general health in order to say that this is effective or not.