How safe is this vaccine? Are there any side effects?
Safety data for this vaccine is similar to the available safety data of other pet vaccines currently in use. The vaccine is licensed by the United States Department of Agriculture and is recommended by thousands of veterinarians nationwide. The vaccine is safe for use in pregnant and lactating dogs, puppies as young as four months and healthy older dogs.
Side effects reported by veterinarians have been few and mild. Less than one percent of vaccinations result in a mild swelling at the injection site. The swelling does not bother the dog (there is no itching or pain) and the swelling resolves without treatment in about three weeks. Occasionally, a veterinarian may drain fluid from the swelling or prescribe antibiotics to speed up healing. Rarely (less than one-tenth of one percent of vaccinations), dogs have experienced mild cases of vomiting, diarrhea or lethargy for one to two days after vaccination. Cases of life-threatening anaphylaxis (an acute, "allergic" reaction to the vaccine) are extremely rare with this vaccine. These are estimated to occur at between one and three cases per million doses of vaccine administered.
A decision to vaccinate your dog should balance the risk and consequence of a venomous snakebite with the risk and consequence of vaccination. We recommend that you talk with your veterinarian about these risks.
I found this here: http://www.redrockbiologics.com/FAQ.html#5