[1] Hlth Protect Agcy Ctr Infect, Immunisat Hepatitis & Blood Safety Dept, London NW9 5EQ, England
[2] Manchester Royal Infirm, Hlth Protect Agcy NW, Meningococcal Reference Unit, Manchester M13 9WL, Lancs, England
[3] Dept Hlth, London SE1 6TE, England