1. From the Department of Chronic Diseases and Ageing Norwegian Institute of Public HealthOslo Norway
2. Department of Endocrinology, Morbid Obesity and Preventive Medicine Oslo University HospitalOslo Norway
3. Institute of Clinical Medicine University of OsloOslo Norway
4. Centre for Fertility and HealthNorwegian Institute of Public HealthOslo Norway
5. Department of Influenza Norwegian Institute of Public HealthOslo Norway
6. Department of Transplantation Medicine Oslo University Hospital Oslo Norway