Complex sentence: In 2001-2002, he was co-chair of the Canadian Society for International Health, and between 2001-2003, he was President of the International Child Health Section of the Canadian Paediatric Society.
Split into simpler sentences: In 2001-2002, he was co-chair of the Canadian Society for International Health. And from 2001-2003, he was President of the International Child Health Section of the Canadian Paediatric Society.