MEMO: COVID-19 Testing Update

TO:  Health Care Professionals in the Niagara Region

FROM: Andrea Feller, MD, MS, FAAP, FACPM, Associate Medical Officer of Health

REFERENCE: COVID-19 Testing Update

DATE:  June 2020

Dear Colleagues,

It is important that we share what we have learned about COVID-19 testing. Like all medical tests, this test is intended to be used after a clinical assessment has determined suspicion of illness. It does not work well if there is a low pre-test probability. In that situation, the chance that a positive lab result indicates acute infection (positive predictive value) is fairly low.

In Niagara, positive results in truly asymptomatic people almost always are a result of past infection. Also, the vast majority of transmission has occurred from symptomatic cases, including in congregate settings.

• If a patient has symptoms, it's a great diagnostic test. It’s also a good high-risk surveillance test (known exposure after review by Public Health). It’s worth re-emphasizing that it’s important to test people with very mild symptoms. We have had many cases eventually swabbed and diagnosed with COVID-19 after an initial diagnosis of allergies, strep throat, otitis, or other mild illnesses.
• If a patient is tested, but does not have symptoms, this is “screening”. This is not recommended given the patient restrictions and other impacts that arise from a positive result that most likely does not represent acute infection, the discomfort of the swab if done properly, and the provincial backlog from many government directives or guidance on screening.

We have and continue to experience many residents refusing recommended testing due to the discomfort of a prior test/swab experience, as part of government screening policies or because they just wanted to "know".  At this point, it’s still an uncomfortable NP swab.

Due to all of the above, we have strongly requested that the province change the directive that visitors of long-term care homes must have a negative COVID test result, within 14 days of visiting their loved ones.

Additional Information

We acknowledge that this may be a difficult conversation with your patients. We encourage you to discuss the risks and benefits of testing with your patients, and to support them in meeting requirements to visit loved ones in long-term care or other circumstances requiring testing.

Public health is a great local resource for advice on this if you have questions about the test. We have reviewed all of our positive lab results in Niagara, traced, and investigated them. In addition, we have the experience from tens of thousands of negatives.

If you have questions about how to get your patient tested please contact the COVID-19 Information Line at 905-688-8248 and press 7, then follow the prompts. Otherwise if you have further questions about this memo, please contact me directly. Thanks for all you are doing to help Niagarans get, and stay healthy.