Funding for this research was provided by:
Astma- och Allergiförbundet
Centrum for Allergiforskning
Received: 5 June 2019
Accepted: 28 August 2019
First Online: 5 September 2019
Ethics approval and consent to participate
: This study was approved by the Regional Ethical Review Board in Stockholm, Sweden (Dnr 2009/84-31/5). Personal data were treated according to the Swedish Personal Data Act. Parents provided written informed consent prior to participation.
: Not applicable.
: The authors declare that they have no competing interests.