Immunization standards

Efficient means to determine Hib component in liquid vaccine presentations, for different vaccines, produced by different manufacturers.

The WHO Prequalification of Vaccines Programme (PQV) today publishes the results of a small study to test five selected vaccines, using two different test protocols and two reference standards. The data demonstrated that, for one of the test protocols (applied by Laboratory 1), precise measurement of the critical vaccine parameter ― total and unconjugated PRP ― was possible for complex matrices of immunogens, adjuvants and excipients for five different vaccines. This will be of interest to national control laboratories (NCLs) who undertake testing of diphtheria, tetanus, whole-cell pertussis (DTwP) based pentavalent combination vaccine (liquid DTwP-HepB-Hib presentation).

Liquid DTwP-HepB-Hib presentation is a high-priority vaccine for WHO, which receives many applications for prequalification. But the various vaccine combinations differ according to Haemophilus influenzae type b (Hib) carrier protein, antigen combinations, adjuvant, and preservatives and other excipients. Each of these factors can interfere in the determination of the polyribosyl-ribitol-phosphate (PRP) content, the active ingredient of a vaccine that prevents infection by H. influenzae type b. Laboratories performing tests on behalf of the WHO PQV must establish and validate various methodologies to determine the PRP content of the individual products. This is very time-consuming and slows the testing process. But application of the test protocol of Laboratory 1 offers NCLs an efficient means of determining Hib component in liquid vaccine presentations, for different vaccines produced by different manufacturers.

A collaborative study is now planned, whereby a broader range of control laboratories (NCLs and manufacturers) will apply and verify the test protocol.

Additionally, a hands-on training course on the test protocol will be held in Rome, Italy, 29 September to 3 October 2014 for NCLs of countries producing or intending to produce pentavalent vaccines for prequalification. Since this course is already fully booked, further courses will be organized. No fees will apply for NCLs. Places will be available for up to 5 participants from quality control laboratories, preferably located in countries producing or intending to produce pentavalent vaccines. For further details, please contact Dr Ute Rosskopf: rosskopfu@who.int.

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