If you can't make your appointment to get tested for COVID-19, let the testing facilities know.

That's the message from Waterloo Region's testing partners, who say that no-shows and last-minute cancellations are negatively impacting the number of tests they can do each day.

At the Grand River Hospital testing site, for example, health-care workers were conducting about 550 tests per day. Since they started testing by appointment only, which is now mandatory across the province, the average sits at 389.

Officials at the site say it's because people are booking appointments at all four sites in Waterloo Region, and then going to the earliest or most convenient one without cancelling their other appointments.

"We're just asking that every person that comes for testing does select a site and stick to their appointment time," said operations Manager Sarah Sullivan.

Even sites that had already been by appointment only are seeing the new trend. Rex Mohammed, who operates the KW4 testing site out of his walk-in clinic in Waterloo, says that, for the past week, the clinic has seen 20 to 30 no-shows per day.

That's a significant blow to their daily testing capacity of 150 to 200 tests.

"When we don't have people showing up, it means that we are wasting our resources in terms of the pre-registration process," Sullivan said. "Also not maximizing the efficiency of our site."

Mohammed says it's frustrating because of the wasted staff time, leaving people who are desperate to get tested to wait longer than they need to.

Management at both locations said people are booking appointments at several locations and going to the earlier one. At Westmount Plaza, it's a dilemma for dispatchers.

"They actually hear in the background, people are calling Cambridge, calling St. Mary's site, all of the sites, including Hamilton," Mohammed said. "You can hear the speaker at the sites as they are booking appointments with us."

Ontario as a whole is administering upwards of 40,000 tests per day, but there is such a significant backlog that some tests are being sent to the United States for laboratory processing.

That confirmation from a spokesperson at the Ministry of Health comes a day after Premier Doug Ford acknowledged that the province is reaching its limit when it comes to testing for COVID-19 during Ontario’s second wave of the disease.