Each set of allergy vaccines (extract) is prepared in one of our offices under controlled sterile conditions by mixing special combinations of stock materials. The mixture is individually prepared based upon your history and skin test results. The number of sets and dilutions of vaccine you require for treatment depends upon the number and severity of your reactions. Extracts are prepared in several strengths with the strongest identified as full strength. It is necessary to begin treatment with the weaker doses to allow you to tolerate the injections with a minimum possibility of reactions.