The ACIP discourages the practice of prefilling vaccine into syringes, primarily because of the increased possibility of administration and dosing errors. An exception may be considered when only a single type of vaccine is to be administered during a clinic (e.g., influenza). Another reason to discourage the practice in general is that some vaccines have a very limited shelf life after reconstitution. If the reconstituted vaccine is not used within the designated time period, it must be discarded. A chart of the time allowed between reconstitution and use, “Vaccines with Diluents: How to Use Them,” is available at www.immunize.org/catg.d/p3040.pdf. For more information on prefilling syringes, please read www.immunize.org/technically-speaking/20110901.asp.