It is WHO policy to supply biological standards directly to the end-user.

NIBSC supports this policy and, in general, does not supply distributors. However, if you prefer to order through a distributor or an importer, please ensure the order includes a letter or traceable e-mail from the end-user stating they are aware that material can be obtained direct from NIBSC and of the NIBSC handling charge, but prefer to obtain the material via the distributor.