WHO/BS/2014.2239 International collaborative study for the calibration of a replacement IS for the WHO 1st IS for Haemophilus influenzae type b polysaccharide

Overview

In this report we present the results of a collaborative study for the preparation and calibration of a replacement International Standard (IS) for Haemophilus influenzae type b polysaccharide. Two candidate preparations were evaluated. Thirteen laboratories from 9 different countries participated in the collaborative study to assess the suitability and determine the PRP content of two candidate standards. On the basis of the results from this study, it is recommended that Candidate 2 (NIBSC code 12/306) is established as the 2nd WHO IS for PRP Standard with a content of 4.904 ± 0.185 mg/ampoule, as determined by the ribose assays carried out by 11 of the participating laboratories (expanded uncertainty calculated using a coverage factor of 2.23 which corresponds to an approximate 95% level of confidence).