1. Division of Infection Control and Environmental Health Norwegian Institute of Public Health 0213 OsloNorway
2. K. G. Jebsen Centre for Influenza Vaccine Research University of Oslo 0424 OsloNorway
3. The Influenza Centre Department of Clinical Science University of Bergen 5021 BergenNorway
4. Department of Research and Development Haukeland University Hospital N5021 Bergen Norway