[1] Birmingham Heartlands Hosp, Dept Haematol, Birmingham B9 5ST, W Midlands, England
[2] Birmingham Heartlands Hosp, Publ Hlth Lab, Birmingham B9 5ST, W Midlands, England
[3] Univ Birmingham, Canc Res UK Inst Canc Studies, Birmingham, W Midlands, England
[4] Manchester Royal Infirm, Dept Clin Virol, Manchester M13 9WL, Lancs, England