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Seven laboratories from 5 different countries participated in the calibration of the 7th British Working Standard (BWS) for blood coagulation factors II, IX and X. The candidate, 15/182, was assayed for Factors II and X potencies against the 4th International Standard (IS) for Factors II and X, Concentrate (11/126) and for Factor IX potency against the 5th IS for Factor IX, Concentrate (14/148). Intra-laboratory GCVs for all 3 factors were less than 10%, with the majority less than 5%. Inter-laboratory GCVs were 3.4%, 3.2% and 2.3% for FII, IX and X respectively. All participants agreed with the value assigned and preparation 15/182 was established by NIBSC in October 2017 as the 7th BWS for FII, IX, X Concentrate with potencies of 6.0 IU/ampoule, 6.7 IU/ampoule and 4.9 IU/ampoule for FII, IX and X respectively.

Enterovirus A71 (EV71) is the major causative agent of severe and fatal hand, foot and mouth disease. There is plenty of evidence that EV71 has circulated widely in the Western Pacific Region for the last twenty years. Vaccines against EV71 are already available or under development. A collaborative study to establish the 1st WHO International Standard for anti-EV71 serum (Human) was conducted to ensure that methods used to measure the serum neutralizing activity or antibody levels against EV71 are accurate, sensitive and reproducible. Two candidate samples as well as a third candidate reference containing low anti-EV71 antibody titre were produced from plasma samples donated by healthy individuals. All three serum samples exhibited good levels of neutralizing antibodies against a wide range of EV71 strains of various genotypes. The study showed that between laboratory variations in neutralization titres were significantly reduced when values were expressed relative to those of either of the two candidate sera. Sample 14/140 was established as the WHO 1st International Standard for anti-EV71 serum (human), 14/138 as its potential replacement and 13/238 as a WHO Reference Reagent, with assigned unitage of 1,000, 1090 and 300 International Units (IU) of anti-EV71 neutralizing antibodies per ampoule, respectively.

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 (polyribosyl ribitol phosphate; 5-d-ribitol-(1 → 1)-β-d-ribose-3-phosphate; PRP). 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, Candidate 2 (NIBSC code 12/306) has been established as the 2nd WHO IS for PRP by the Expert Committee of Biological Standards of the World Health Organisation with a content of 4.904 ± 0.185mg/ampoule, as determined by the ribose assays carried out by 11 of the participating laboratories.