Antibody concentration of > 0.1 IU/mL is usually considered protective. Responder status is determined according to the ratio of a one-month, post-vaccination sample to pre-vaccination concentration of Diphtheria IgG Abs as follows: 1. If the post-vaccination concentration is less than 1.0 IU/mL, the patient is considered a nonresponder. 2. If the post-vaccination concentration is greater than or equal to 1.0 IU/mL, a patient with a ratio of less than 1.5 is a nonresponder, a ratio of 1.5 to less than 3.0, is a weak responder, and a ratio of 3.0 or greater, is a good responder. 3. IF the pre-vaccination concentraiton is greaer than 1.0 IU/mL, it may be difficult to assess the response based on a ratio alone. A post-vaccination concentration above 2.5 IU in this case is usually adequate.

Include patient immunization status on requisition. Pre and post specimens submitted. Post sample should be drawn 30 days after immunization and must be received within 60 days of pre sample.