The move moves up the expected second doses for those Regions by a month.
The move follows a growing number of cases being diagnosed in the province being the more contagious Delta variant.
The areas with high Delta cases being identified and who will see their second dose eligibility moved up include: Toronto, Peel, York, Halton, Porcupine, Waterloo and Wellington-Dufferin-Guelph.
Eligible residents in the mentioned areas will be able to book either through the Province’s Booking Site, through Public Heath Unit websites that use their own booking sits or through participating pharmacies.