Funding for this research was provided by:
Council on grants of the President of the Russian Federation (075-15-2019-393)
Article History
Received: 24 July 2019
Accepted: 18 August 2019
First Online: 29 August 2019
Compliance with Ethical Standards
: All procedures within the study (examination, sampling) were performed in accordance with the principles of the Declaration of Helsinki and later amendments (2013). The protocol of the present study was approved by the Local Institutional Ethics Committee at Yaroslavl State University (Yaroslavl, Russia). Informed consent was obtained from children’s parents or legal representatives.
: The authors declare that they have no conflict of interest.