Thought of the Day - July 8 - Developments in Testing

As you now there are two main types of testing available for SARs-CoV2.

• Antigen Tests (Do You have COVID-19?) - (RT-PCR) Nasal swab test looking for the coronavirus itself.

• AntiBody Tests (Have You Had COVID-19?) - (serological) Examination of proteins in the blood for coronavirus antibodies, or (PCR) via a swab.

Antigen testing availability has been increasing in Canada as case-loads go down (see blog on BC drive-through testing experience: https://clifffraser0.wixsite.com/covid-19/post/thought-of-the-day-june-2-testing-testing-check-1-2). With the exception of BC and Newfoundland testing levels are on par with most western counties, and Alberta and Ontario continue to match the frenetic pace of the USA.

There are new Antigen Tests on the market that provide results in 30 minutes. Test strips contain artificial antibodies designed to bind to coronavirus proteins. Since these antigen tests do not involve any amplification process, swab samples may lack enough antigen material to be detectable. This may result in higher false negative tests than the 30% rate in RT-PCR. The advantage of using these tests is simply they are quick and cheap.

But Antigen testing is only part of the answer (see https://clifffraser0.wixsite.com/covid-19/post/thought-of-the-day-june-10-antigen-testing-limitations) we also need to be doing antibody testing here in Canada. Some of the reason include:

• To understand the level of infection (how well is testing, tracking and tracing really working);

• Understanding the ratios of asymptomatic/mild symptom cases to those with identifiable symptoms (are they 25%, 50% or 90% of cases across Canada);

• To identify and typify "hotspots" (what institutions, demographics and geography have a high rate of infection);

• To confirm who has had it in the past to provide closure to those who could not get timely Antigen tests;

• To provide more data on how has COVID-19 spread in Canada;

• To give some understanding of potential immunity, so we can track if and how it lasts (is reinfection possible?).

Back in mid -May. The federal gov't announced:

"What’s next? Soon we will introduce a "serology" test that can tell us if someone has been infected with COVID-19 in the past and has developed antibodies to the virus. Once the serology test has been validated for accuracy, the test results will be used to get a better sense of where the virus has been and how to further prevent its spread as we move into the next phase of our pandemic".

After several months of stalling since the May announcements, that included Antigen Test Canadian approvals, I have managed to find only two clinics that are starting to do serology tests: creaMeD in Quebec, and Medcan in Toronto. Surprisingly I did not manage to find anything in Alberta, who had threatened to break rank and move forward on their own some months ago. Alberta are primarily using Antibody testing for surveys and research. BC's Heath Page just says there are no antigen tests available here.

In the meantime Canadian producers of antigen tests have at least been able to find markets in Europe and the US, while awaiting their home country to move forward.

The latest at the federal level is that is our "national immunity task force" has started testing thousands of blood samples. These samples are from donated blood, thus they are in no way a random sample reflective of the general population, but they will at least provide a first glimpse at the infection rates here in Canada. And, as they are anonymous, they do not require any government policy on whether asymptomatic Canadians are allowed to know if they have had COVID-19. There is also a second campaign underway screening blood taken from pregnant women in their first trimester. In this case the women will be told; I guess these women can handle the truth, and are not going to be affected by issues suggested by testing detractors: excessive partying, or exploitation by employers who will move them to high-exposure roles.

Antibody studies in the US and Spain have indicated ten-times more people have the antibodies than have been diagnosed as having COVID-19. Here is my estimation across Canada as of July 4. Hopefully in the next month when studies start to provide results we will have better figures.

Cheers

Cliff