Nearly 11,000 Ontarians who have been tested for COVID-19 are waiting for their results, as the backlog at the province's public health lab continues to grow.

New figures published Thursday by the Ministry of Health show 10,965 people are "under investigation" for coronavirus, which means a sample has been taken, but the test has yet to be processed.

Ontario has faced criticism for the slow pace of testing, trailing every other province except PEI on a per capita basis for the number of tests conducted so far.

Epidemiologists say widespread testing is an important component of the fight against COVID-19 and accurately tracking the spread of the virus.

Ontario has produced an average of 2,500 test results daily since Tuesday. Provincial health officials said Thursday they expect to reach a daily rate of 5,000 tests by the end of this week.

The province hopes to be "making a dent in the backlog by early next week," said Vanessa Allen, chief of medical microbiology at the Public Health Ontario laboratory, during a briefing with reporters on Thursday.

People are reporting waits of five days or more for their results, including an Ontario cabinet minister. Treasury Board President Peter Bethlenfalvy tweeted that he received his result Wednesday, six days after being tested, and is negative for COVID-19.

On March 18, when the backlog meant a four-day wait for test results, Heath Minister Christine Elliott called the delay "not acceptable."

Provincial health officials said Thursday that Ontario aims to ramp up its daily rate of testing by 3,000 to 4,000 tests each week, with the target of nearly 19,000 tests per day by April 17.

Ontario has until restricted testing largely to health care workers, people who have travelled outside the country, and people already in hospitals and long-term care homes. Health officials say the system simply doesn't have the capacity to test everyone who has symptoms of COVID-19.

Premier Doug Ford said Monday that a short supply of reagent — a substance or mixture needed for chemical analysis — is the "biggest issue" slowing down the pace at labs.

"We're going to do everything we can to get more reagent," he said. "We will spare no expense to make sure we get hold of this product."

However the province's chief medical health officer Dr. David WIlliams did not identify a shortage of reagent as the key to the bottleneck during his daily media briefing on Thursday.

The province's efforts have focused on increasing the number of labs that can run COVID-19 tests. Ontario is currently processing tests at its four provincial public health lab sites, as well as eight hospital labs and two commercial labs. Officials say they intend to expand to as many as 30 to 40 lab sites.

Williams said getting a new site certified takes time because its first 50 tests must be confirmed at the provincial labs.

The province has conducted 38,550 tests but has only provided 27,585 results. By contrast, Alberta, British Columbia and Quebec have each processed more tests than Ontario despite their lower populations.