REGINA -- Saskatchewan's COVID-19 vaccination booking system will be available to residents 44-years and older, starting at 8 a.m. Thursday.

This applies to all of Saskatchewan except for those in the Northern Saskatchewan Administrative District, where age eligibility remains at 40 and older.

The province said the age range applies to all immunization clinics, including booked appointments, drive-thru, walk-in and mobile.

Appointments can be made online or over the phone at 1-833-SaskVax (1-833-727-5829).

The Saskatchewan Health Authority tweeted out a reminder to residents on Thursday morning, advising that the demand for appointments in the province currently outweighs vaccine supply.

"Additional clinics will be added to the Patient Booking System as new vaccine shipments are received," the SHA said, in another tweet.

The Saskatchewan government announced Tuesday it will use the AstraZeneca shot to vaccinate people age 40 and older against COVID-19.

"With the recent change to the minimum age for use of the AstraZeneca vaccine, residents should be aware that any one of the three approved vaccines - Pfizer, Moderna, or AstraZeneca - may be offered at their chosen clinic. All are safe and approved for use," the SHA said in a release.

According to the government, vaccine eligibility is expected to open to those 40 and older on April 28.

Once vaccine eligibility has been opened to the over-40 age group, the province said it will prioritize remaining frontline workers, including teachers and educational staff, correctional staff, border security agents, police officers, firefighters and frontline healthcare workers employed by the Saskatchewan Health Authority or private employers, such as dentists, optometrists and chiropractors.