Katja Höschler1, Maria C Zambon2. 1. Virus Reference Department, Reference Microbiology, National Infections Service, Public Health England, London NW9 5HT, UK. Electronic address: katja.hoschler@phe.gov.uk. 2. Virus Reference Department, Reference Microbiology, National Infections Service, Public Health England, London NW9 5HT, UK.