[1] Univ E Anglia, Natl Blood Serv, Div Transfus Med, Cambridge CB2 2PT, England
[2] Natl Blood Serv Manchester, Manchester M13 9LL, Lancs, England
[3] UCL Hosp, London WC1E 6DB, England
[4] Publ Hlth Lab Serv, Ctr Communicable Dis Surveillance, Natl Blood Serv, London NW9 5EQ, England
[5] Royal Infirm, Dept Transfus Med, Edinburgh & South East Scotland Blood Transfus Se, Edinburgh EH3 9HB, Midlothian, Scotland
[6] Hammersmith Hosp, Royal Postgrad Med Sch, London W12 0HS, England
[7] Natl Blood Serv, London NW9 5BG, England