1 Department of Vaccine Preventable Diseases, Division of Infection Control and Environmental Health, Norwegian Institute of Public Health, Postboks 222 Skøyen, Oslo 0213, Norway. Electronic address: jacobdag.berild@fhi.no.
2 Department of Vaccine Preventable Diseases, Division of Infection Control and Environmental Health, Norwegian Institute of Public Health, Postboks 222 Skøyen, Oslo 0213, Norway. Electronic address: anneke.steens@fhi.no.
3 Department of Vaccine Preventable Diseases, Division of Infection Control and Environmental Health, Norwegian Institute of Public Health, Postboks 222 Skøyen, Oslo 0213, Norway. Electronic address: brita.askeland.winje@fhi.no.
6 Department of medicine, Ålesund hospital, Møre and Romsdal Hospital Trust, Postboks 1600, Ålesund 6026, Norway. Electronic address: helene.daae-qvale.holmemo@helse-mr.no.
7 Department of Vaccine Preventable Diseases, Division of Infection Control and Environmental Health, Norwegian Institute of Public Health, Postboks 222 Skøyen, Oslo 0213, Norway. Electronic address: didrikfrimann.vestrheim@fhi.no.