April 3, 2020

Test that show immunity to the COVID-19 virus

And, check out Kim Bolton on BNN Bloomberg

So far, the FDA has granted emergency use authorizations to more than 20 commercial COVID-19 diagnostic tests, panels and assays. All of them detect live infections by searching for specific nucleic acids, the small pieces of RNA produced by the novel coronavirus, within swabs and respiratory samples.

However, a new antibody test rolling out in the US within weeks offers a glimmer of hope. These tests will be able to tell whether a person has already had COVID-19, regardless of whether they showed symptoms. A positive result would mean they’re probably immune.

Widespread antibody testing could divide America into two groups: the vulnerable, and the recovered. The latter could slowly go back to work, breathing life into the US economy and helping us get back on track before a vaccine becomes available.

Antibody testing

Antibody tests differ from the diagnostic tests used to determine whether someone has an active COVID-19 infection. The latter involves taking samples of mucus and saliva and running a test in a lab to see whether those samples contain the coronavirus’ genomic sequence. The results can take one to two days. A serological test, on the other hand, can tell within minutes whether a person has coronavirus antibodies — similar to the way home pregnancy tests and HIV antibody tests work. A kit includes a needle (to prick your finger), a 3-inch mixing stick, and a test solution.

The tests look for two antibodies in the blood: immunoglobulin M (IgM) and immunoglobulin G (IgG.) Antibodies are the body’s way of remembering how it responded to an infection so it can attack again if exposed to the same pathogen. IgM antibodies are the first line of defense and appear within several days of the infection. IgG antibodies come later, as the body is clearing up the infection.

While IgM and IgG fight all kinds of infections, the blood tests for COVID-19 look for protein particular to the virus so they know the body is producing antibodies to the coronavirus and not, for example, the seasonal flu.

Antibody tests are critical in the response to the pandemic. They’d help figure out who has already been sick — whether they had significant symptoms or not — and therefore, who is probably immune enough to the virus to safely move around the world normally. They’ll also help public health officials understand how much of the population has been infected by the coronavirus. Dozens of companies are working to develop antibody tests, as are researchers at the Centers for Disease Control and Prevention.

FDA authorizes first antibody-based test for COVID-19

The test is produced by the biotechnology company Cellex. Health care providers have to draw blood from a patient’s vein to run the test, and it can only be done in certified labs — not a doctor’s office. It takes 15 to 20 minutes to get a result.

It is the first of an expected flood of such tests as companies race to develop them. Antibody tests are already being used in several countries, including China, South Korea and Singapore.

“Antibody positivity likely means a person has recovered and can’t be reinfected. This test will be extremely valuable, especially for healthcare workers,” said Alan Wu, a professor of laboratory medicine at the University of California, San Francisco and chief of the clinical chemistry and toxicology laboratories at Zuckerberg San Francisco General Hospital. His team is testing several possible COVID-19 blood tests.
Source: MIT Technology Review

Kim Bolton, BSD’s President and Portfolio Manager, was featured on BNN Bloomberg’s Market Call earlier this week. Check out his interview here.