Establishment of a dried standard pertussis vaccine

Summary The potency of an own Dutch standard pertussis vaccine B was determined by indirect comparison in three stages (B with A; A with U.S.A. Reference no. 5; U.S.A. Reference no. 5 with U.S.A. Standard no. 4) with the U.S.A. Standard no. 4 in the intracerebral mouse-protection test. The values found were checked by direct comparison with U.S.A. Reference no. 4 in Holland and U.S.A. In this way a definitive value of 3.7 units/ml was given to this standard. The reasons are discussed for giving a unit value to a standard, although this unit value cannot be determined accurately in a biological test.