There are numerous good reasons for Ontario being behind on COVID-19 testing

Why is COVID-19 virus testing so limited in Ontario? Tests that should take only hours to complete are taking several days to report and people who want to be tested are being told that they do not “qualify.”

On social media, the need for more testing is a common topic. Other countries, like South Korea and Taiwan, have kept the virus at bay using extensive testing and quarantine of positive patients and their contacts. As social distancing creates psychological strain and economic hardship, the complaint becomes, “If I knew I tested negative, then I could get together or work with other people who also test negative.”

South Korea has controlled COVID-19 by running 20,000 tests a day for its 50 million population and an equivalent number for Ontario would be about 5,000 daily tests. This is the number targeted by Public Health Ontario. However, according to the ministry of health website, although nearly 4,000 daily tests are currently being submitted for testing, only about 2,000 a day are being completed. As of Sunday, more than 8,000 tests were listed as “pending” or waiting analysis.

There are a multitude of ideas on social media as to why lab testing cannot keep up with clinical demand, including the accusation that government laboratories are inefficient. However, the real reason for slow and limited testing is that the process for detecting COVID-19 is complicated and requires a variety of materials, which are in enormous international demand and in short supply.

The complexity of the testing process begins with obtaining a sample for testing, generally using a naso-pharyngeal swab. The swab used in this test must go through the nose to contact the back of the throat. The synthetic material and the stick used to place the swab at the back of the nose must be thin enough and strong enough to pass through the nasal passages.

These swabs are back ordered everywhere and companies are struggling to increase supplies. Rationing these swabs is the reason that COVID-19 assessment centres in Ontario limit tests to higher risk patients.

The next step when the swab arrives in the laboratory is to extract RNA from the sample. RNA is the viral genetic material that enables invasion and viral multiplication within human cells. The unique RNA sequence present in two COVID-19 genes is used to identify the virus. Unless the RNA is harvested carefully without breakdown, the eventual testing of the RNA will not be reliable. Unfortunately, the lab kits used to extract RNA are in very short supply. Most of the backlog in Ontario testing probably relates to a shortfall of RNA extraction kits.

Multiple extracted RNA specimens are then loaded in an automated analyzer that takes hours to complete detection of the two COVI-19 genes. With the addition of some hospital and commercial labs to Ontario testing centres, analyzer capacity should not be a problem in achieving 5,000 tests a day in this province. Most analyzers can complete more than 1,000 tests in 24 hours.

However, the reagent kit that is used to identify the two COVID-19 genes in the high throughput analyzer may be in short supply now or (as access to RNA extraction kits increases) in the near future. Companies are ramping up supply of the reagent kits, but every wealthy country in the world is currently competing for this resource.

Demand for COVID-19 testing leads to suggestions that new methods of testing should be developed. However, the development of a new lab protocol requires intensive evaluation and quality control. We need assurance that the new laboratory test is sufficiently sensitive to detect virus in most affected patients. Otherwise health-care workers could be exposed to the virus without protective equipment since they might think the patient is virus free.

Ontario is fortunate to have world leaders in laboratory medicine in our public health facilities, hospitals and commercial labs. They are exploring all options to source the critical supplies necessary to scale up testing. Maintaining the quality of lab testing is crucial to protect health-care workers. We need to accept rationing of testing and longer than expected turnaround times while we hope that increased international supplies become available in the weeks ahead.

In the meantime, physical distancing, hand washing and everyone possible staying at home are crucial to reducing the spread of this virus.

The process for detecting COVID-19 requires a variety of materials, which are in enormous international demand