Anyone in Toronto over the age of 12 seeking to participate in organized indoor sports will have to present proof of vaccination, the city's medical officer of health said.

Dr. Eileen de Villa issued a letter mandating proof of vaccination on Thursday. It means active participants, players, coaches, caregivers, volunteers, and anyone else involved with organized indoor sports will be required to follow the mandate, which comes into effect Monday, Nov. 1.

"We have seen COVID-19 cases and outbreaks linked to indoor sporting and recreational events," de Villa said in a statement. "With one consistent vaccination policy — in addition to measures of self-protection — we decrease the risk of COVID-19 transmission in these settings and ensure these activities continue in the safest manner possible."

The City of Toronto says the additional measure is necessary to reduce COVID-19 transmission indoors. Participants can provide proof of vaccination as per the Ontario Ministry of Health's requirements, the same rules which are in place for businesses and venues.

Proof of vaccination, along with identification, will be required to be shown before entering the facility hosting the indoor sports. The new rule comes into place as many local sports organizations have introduced their own vaccination policies.

As of Oct. 7, 81.6 per cent of Toronto residents age 12 and over are fully vaccinated according to the city's data.