Ontario is offering faster second COVID-19 vaccine doses to more residents.

Starting tomorrow, youth aged 12 to 17 who live in hot spots for the Delta variant can book faster appointments starting at 8 a.m.

All adults in Ontario who received their first dose of an mRNA vaccine can book accelerated second appointments on Monday.

That change means approximately 1.5 million Ontarians are eligible for an accelerated second dose.

The province says it's expanding eligibility as 76 per cent of Ontarians have at least one vaccine dose and more than 30 per cent are fully vaccinated.

Shots were initially booked four months apart in Ontario but the province is shortening the interval based on supply and risk from the more infectious Delta variant.

Health units covering Durham, Halton, Hamilton, Peel, Porcupine, Simcoe-Muskoka, Toronto, Waterloo, Wellington-Dufferin-Guelph and York are designated hot spots for the variant.