BARRIE, ONT. -- The Royal Victoria Regional Health Centre (RVH) Immunization Clinic in Barrie, Ont. has tirelessly tried to get COVID-19 shots in the arms of residents.

Stella Johnson oversees the clinic at 29 Sperling Drive and says they have seen a significant increase in the number of eligible people wanting their second dose.

"We are seeing some days up to 1,800 patients per day, and we are now open seven days a week," notes Johnson.

She says appointments are booked until the first week of July.

On Wednesday, the criteria expanded for those eligible to get fully vaccinated. Now, anyone who got their shot before, or on May 30, can book an appointment.

Johnson encourages anyone who has not received their first dose to book it. She says the clinic had 500 first shot doses available for walk-ins on Tuesday, and they nearly met their target. "We got 300 dose-ones done without any appointments, and then we used our standby list to make sure that every dose was used."

"But, there are over 140,000 people across Simcoe Muskoka who still need that first dose," Johnson adds.

Mixing and matching vaccine doses has become common as the province ramps up immunizations, but that has some turning away from their appointments.

In Simcoe Muskoka, Johnson says clinics were mainly administering the Pfizer vaccine because the region was one of the early adopters to open immunization clinics in December.

"Then Moderna joined the scene in March and April, and for a lot of individuals, Pfizer was their first dose, and we don't have Pfizer in the same quantities as we do other brands," she says.

The RVH immunization clinic is running as a multi-mRNA clinic using Pfizer and Moderna available every day, according to Johnson.

As for those working alongside Johnson in the clinic, she says many are family and RVH physicians and nurses, along with those who came out of retirement to lend a hand.

"I think it's nice to hear the stories of more than 12 retired nurses that have come out of retirement only since December to contribute in the effort," says Johnson.

Complete information on how to book an appointment at one of the region's COVID-19 vaccination clinics is available here.