TORONTO -- Now that over half of Torontonians 18 and older have received their first dose of a COVID-19 vaccine, a new urgency lingers — the second dose.

Vaccine recipients across the country are recommended a second dose within four months of their first, in accordance with the National Advisory Committee on Immunization’s recommendations. But the affirmation of a date and location for a second appointment depends on where you received your first dose.

The provincial booking system used for city-run immunization clinics prompts users to book both doses at the same time, a Toronto Public Health spokesperson told CTV News Toronto. They said those who received their first vaccine at a hospital immunization clinic or pharmacy and did not receive a second dose appointment, should contact the respective institution.

The Ontario Ministry of Health also told CTV News Toronto that, “Individuals should have been booked for the second dose at the time they booked their first.”

But, pop-ups and mobile vaccine clinics are run by a range of health-care partners and their approaches to booking second dose appointments varies.

Less than a week ago, Maimuma Gaye received her first COVID-19 vaccine at a Michael Garron Hospital pop-up. While her six-month-old twins were napping, she hurried to Warden Hilltop Community Center.

After Gaye received her first dose, the nurse who administered the vaccine mentioned she’d receive an email about a second dose. Gaye anticipated an email update in 24-hours, but she still hasn’t received one.

“From a comparison standpoint, I took my mom to get her shot at Centenary Hospital and she got right away the booking for the first dose,” Gaye said. “All my friends who got their first shot also got a date. I’m kind of anxious just needing to know.”

Michael Garron Hospital told CTV News Toronto that those who received their first shot at an East Toronto Health Partners COVID-19 immunization clinic or pop-up will be contacted approximately 12 weeks after their first dose to confirm their second appointment.

“That’s three months of not knowing,” Gaye said.

Women's College Hospital said their pop-ups don’t schedule second dose appointments. A hospital spokesperson said they would reach out when “dose 2 plans are made” and that they would host similar pop-ups for second doses.

In response to a woman who received her first dose at a Brampton Islamic Centre pop-up, with no second appointment in sight, the Region of Peel tweeted: “Depending on the clinic, a follow-up appointment will either be booked before you leave or information will be sent in the coming months with details on how to get your second dose.”

For Gaye and many others, the certainty of a scheduled second dose appointment is absent, but infectious disease specialist Dr. Isaac Bogoch said that while providing second appointments would alleviate concern, “there will be second doses and they will all be at or before four months.”

He took this one step further to say it’s “very likely” many Canadians will get their second shot sooner than the four month interval.