Funding for this research was provided by:
Received: 4 December 2020
Accepted: 4 March 2021
First Online: 17 March 2021
: This study was exempt from review by the Medical Ethics Committee Southwest Holland (reference number 17-032, as it does not fall within the scope of the Dutch Medical Research Involving Human Subjects Act. Written informed consent to participate in the WOWIJS programme was obtained from participating children’s caregivers. For the school-based control group an anonymised data set was used. To protect the children’s privacy in the control group there was no access to personal data such as names or dates of birth or the school they attended.
: Not applicable.
: MWAJ is treasurer of the non-profit SHJG Foundation. The SHJG Foundation takes charge of the implementation of the WOWIJS programme in the city of The Hague. GCK and SIV declare they have no competing interests.