Affiliation: | Author affiliations: Newcastle-upon-Tyne Hospitals, Newcastle-upon-Tyne, UK (B.A.I. Payne, M. Medhi, M. Valappil, U. Schwab); ;Newcastle University, Newcastle-upon-Tyne (B.A.I. Payne); ;Health Protection Agency, London, UK (S. Ijaz, E.J. Savage, O.N. Gill, R. Tedder) |