Funding for this research was provided by:
Universidad de La Frontera (IAF18-0008)
Received: 31 August 2019
Accepted: 29 April 2020
First Online: 19 May 2020
Ethics approval and consent to participate
: The study protocol was approved by the Ethics Committee of the Universidad de La Frontera, Temuco, Chile with resolution number 098/2017. Informed consent from all parents and written consent from children was obtained to consider their participation in the study.
: Not applicable.
: The authors declare that they have no competing interest.