O’Regan, Elisabeth http://orcid.org/0000-0002-1310-957X
Svalgaard, Ingrid Bech
Sørensen, Anna Irene Vedel http://orcid.org/0000-0002-3877-4592
Spiliopoulos, Lampros
Bager, Peter
Nielsen, Nete Munk
Hansen, Jørgen Vinsløv
Koch, Anders
Meder, Inger Kristine http://orcid.org/0000-0002-0743-419X
Videbech, Poul
Ethelberg, Steen http://orcid.org/0000-0002-9709-356X
Hviid, Anders http://orcid.org/0000-0002-7509-9127
Article History
Received: 27 July 2023
Accepted: 21 February 2024
First Online: 4 March 2024
Competing interests
: The authors declare no competing interests.
: This study was performed as a surveillance study as part of the governmental institution Statens Serum Institut’s (SSI) advisory tasks for the Danish Ministry of Health. SSI’s purpose is to monitor and fight the spread of disease in accordance with section 222 of the Danish Health Act. According to Danish law, national surveillance activities carried out by SSI do not require approval from an ethics committee. Participation in the study was voluntary. The invitation letter to participants contained information about their rights under the Danish General Data Protection Regulation (rights to access data, rectification, deletion, restriction of processing and objection). After reading this information, it was considered informed consent if participants agreed and clicked on the link to fill in the questionnaires.