The supply of swabs used to test for COVID-19 is "critically limited," according to the B.C. Centre for Disease Control.

The warning over the nasopharyngeal swabs, which are used to collect samples from patients, appear in guidelines for lab testing on the BCCDC website. Any supply issues could affect the rate of testing at a critical time, as the World Health Organization (WHO) urges increased testing for the disease caused by the novel coronavirus.

B.C. Health Minister Adrian Dix confirmed on Tuesday that it's a problem and that tests are being prioritized while health authorities search for more supplies or other options.

"Every effort is being made to get more swabs," Dix told Stephen Quinn, host of CBC's The Early Edition.

On Monday, WHO director-general urged nations to "test, test, test every suspected case" of coronavirus.

Tedros Adhanom Ghebreyesus said there has not been an urgent enough escalation in testing, isolation and contact tracing, which he described as the backbone of the COVID-19 response.

But Dix says B.C. has led the world in testing, and has swabbed 6,326 individuals for the pathogen as of March 13.

In Canada more than 34,000 have been swabbed, compared to 23,000 in the U.S.

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Dix said health officials are working to be innovative and try out different kinds of swabs.

"We have to concentrate now to control the spread of the virus on specific things, on priority things — breaking up clusters and testing health-care workers," he said.

The Provincial Health Services Authority issued a statement on behalf of the B.C. Centre for Disease Control assuring British Columbians that there are enough swabs to test everyone who needs it.

"We have recently adapted the testing strategy in B.C. People with mild symptoms who can recover on their own at home don't need testing because the medical care and advice is the same regardless of whether they test positive or not."

"We are advising regional health authorities and health professionals who are testing to consider the needs of their populations as they order swabs to ensure resources are distributed appropriately. In the event of shortages, there are other types of swabs available, such as those used for [sexually transmitted infection] testing, that might be used to test for COVID-19."

Presently, B.C. is only testing people who have symptoms or a risk of exposure to coronavirus. That includes people with respiratory symptoms who are hospitalized or likely to be hospitalized, or people who are suspected to be part of a cluster or outbreak.

Provincial health officer Dr. Bonnie Henry has been clear that people with no or mild symptoms — or returning travellers — do not require a test.

Late last week, a global demand for testing supplies forced Ontario to tighten its criteria for who is eligible for COVID-19 testing.

The new guidance released by Ontario's Ministry of Health states that individuals who travelled outside of the country and are exhibiting symptoms of the disease will no longer be tested because of limited supply of viral nasopharyngeal swabs.

If you have a COVID-19-related story we should pursue that affects British Columbians, please email us at impact@cbc.ca.