Some people may think we are too late to this game, and that we are chasing the ball while it is rolling down a hill. How quickly this lock down is over will depend on its citizens abiding by public health suggestions to stay home, and only go out if necessary. Remember, we still have Canadians abroad that are coming into the country, some of which have neglected to inform airlines that they are ill. However, under Canada's Quarantine Act, those returning from travel must by law isolate themselves. My step-dad just returned from Mexico on one of the repatriating flights, and mom returned last week. So their quarantine has started. Fortunately, they have my cousin to help them with groceries, so that they don't have to put anyone at risk.
During today's announcement, the Deputy of Public Health, Dr. Njoo discussed both the rules for the Quarantine Act, but also that they are in the process of validating both serological testing and point-of-care tests. This is recognition that the PCR tests take too long, in some cases having to be transported from facilities via aircraft to reference laboratories. It's nice to know that we won't be 100% reliant on PCR testing, as we heard yesterday that there was a shortage of the reagent for the RNA extraction.
In a previous post, I discussed the lower sensitivity of PCR testing when only a single nasal swab was tested. I followed up with a post on some of the testing measures that were in the primary literature, as researchers race to develop a faster testing method. In that post I very briefly spoke about serological testing.
A serological test uses serum, the fluid component of your blood that excludes the blood cells (red blood cells, white blood cells and platelets) and clotting proteins (fibrinogen). Once a blood sample is obtained, it is allowed to clot in the test tube, then spun down using centrifugal force so that the cells or heavy things end up at the bottom of the tube, and the serum (liquid) remains at the top of the tube. Both serum and plasma have been used to detect antibodies to viruses (such as herpes simplex virus). The antibodies (IgM, IgG, IgA) are proteins produced by immune cells in response to an antigen (the viral particle that enters the body). Once the COVID-19 serological assays have been validated, this will be useful in tracing of exposed individuals, ones that are not showing symptoms. Additionally, it may provide information about exposure that may provide individuals with antibodies that are protective.
Therapeutics Using Serum
In influenza cases (H1N1), serotherapy improved patient outcome if they were given the therapy within the first 5 days of illness, though when given later in the disease (greater than 10 days), it had little value to patient outcome. These are cases studies, and not widely used, but may show promise during the treatment for COVID-19 pandemic. So what is serotherapy? This is the extraction of the antibodies (serum) from one individual that has immunity to a virus, and transfusing (similar to a whole blood transfusion) to an ill individual. Serotherapy has been used in the treatment for venomous organisms such as scorpions, with the horse being used to develop a large amount of these antibodies (antivenom) and can take 6 weeks to develop. I couldn't find any case reports of serotherapy being used for SARS-CoV, or for the current coronavirus, but who knows, maybe we will see some in the future.
I am trying to find current (within the past week) information on research that is occurring into COVID-19 (SARS-CoV-2) testing and treatment. Once serological testing is validated, this is going to be important in the tracing of exposure. The antibody response for patients with COVID-19 is starting to be published.
Most serology tests use ELISA, a protein to antibody linking test that shows up in a colour indicating a yes or no answer (in a qualitative test versus quantitative test). You do have to keep in mind that there are no tests that are 100% specific and 100% sensitive, but we hope to get as few false negatives as possible when trying to rule a disease out. In other words, we would rather have a highly sensitive test (few false negatives) than a highly specific test (few false positives), when we are trying to control a disease from spreading. Worded another way, a falsely positive person, stays in quarantine, doesn't infect anyone, while a falsely negative person does NOT stay in quarantine, going out to infect people.
ELISAs are highly sensitive tests, but are yet to be validated for COVID-19.
Dr. Njoo also reiterated that this is buying us time. Time to develop vaccines and treatments. Both him and the Deputy Minister say that things are going to get worse before they get better. It's best to not get a false sense of security at this time.
I also wanted to mention that yesterday my condo board sent out an alert to residents saying that someone in our building has tested positive. Likely we will all know someone close to us that will be affected by this pandemic. Again, take a read of this woman's article on how she's been able to protect herself with a weakened immune system. The basics: wash your hands, sanitize surfaces, and avoid contact with people (or things people touch).
1) Wash your hands for 20 seconds in a sudsy soap: Check out my colleague’s post (she works in the swine industry – the epitome of biosecurity in Canada).
2) Sanitizing surfaces - Contact Time of the disinfectant is important - Enveloped viruses, such as the flu (influenza) and coronavirus, are easily neutralized with soaps, alcohol (70%), or bleach detergents. Depending on the product you are using, the contact time (time the product needs to sit on the virus to neutralize it) ranges from 30 seconds to 10 minutes. If you wipe away the cleaner too soon (same with the soap being rinsed off your hands too soon), then you have not neutralized the virus.
3) Stay Home if you can, and when out stay 2 meters away from other people.
Edit March 29, 2020: Bill Gates made a comment in this Ted Talk that serotherapy would be more difficult to up-scale.
Edit March 30, 2020: The point-of-care testing that I had mentioned a few posts ago, did get approval by the FDA. See the Promed mail announcement. For more info on the test, check out the Cepheid website. Time will tell when Canadians get access to such testing measures.