TORONTO, ONT. -- SickKids hospital has updated its recommendations for a safe return to school full-time, including guidelines that acknowledge making masks mandatory could be a "complicated" task.

While doctors from the Toronto hospital and other health officials from across Ontario agree face coverings may be useful in halting the spread of COVID-19 among high-school students, they don't recommend them for younger children.

Dr. Jeffrey Pernica, the medical director of infectious diseases at McMaster University in Hamilton, says masks are not the sole line of defence against COVID-19. Pernica says masks can be distracting to younger children, and can have other potential harm if not worn correctly.

Dr. Michelle Science of SickKids says "a bundle of measures" will eliminate risk of transmission within schools rather than one specific precaution. Things like daily screening for symptoms, physical distancing when possible and cohorting should also be in the return plan, she added.

The doctors say evidence is mounting that young children don't play a "significant role" in spreading COVID-19, compared to teenagers and other adults.

The guidelines suggest a full-time, in-person return to school would be best for children, from educational, mental health and social development standpoints.

Dr. Ronald Cohn, the president and CEO of SickKids, says they've had "open and constructive dialogue" with the government of Ontario about reopening schools. The government is expected to unveil its plan for a return to school on Thursday.

Wednesday's document comes six weeks after SickKids unveiled its initial recommendations, and five weeks before the school year is set to begin.

This report by The Canadian Press was first published July 29, 2020.