This week, as the world readies itself to a new normal and gradually lifts confinement rules, I tried to wrap my head around what’s known about serology testing and COVID-19 antibodies.
Before I dive into that, I would just like to leave you with a bit of comic relief that I found in the comment section of a blog post about neutralising antibodies:
“It’s not a furin site [in the coronavirus spike protein], it’s a tiny 5G antenna”
SEROLOGY TESTING IS A GOOD IDEA, IMMUNITY PASSPORTS ARE NOT
Unlike nasal swabs that test the presence of the virus’ genetic material, serology testing uses a sample of blood and looks for the presence of antibodies. These antibodies are produced during (IgM) or some time after (IgG) the infection occurred, thus giving us a more accurate estimate of how many people were infected. For COVID-19, this would be useful data to get a better sense of how widespread the disease is, and also to locate potential plasma donors—one of the current therapies available, currently undergoing clinical trials.
I’ve read an MIT Technology Review article that explained the reasoning behind serology tests very well, but then went on to say that they were also useful for healthcare professionals, because if they knew they were seropositive (meaning they had already had COVID-19 and recovered), they could then “could safely rush to the front lines and perform the riskiest tasks”. Now, they did also mention in passing “assuming they are now immune”, but no further importance was given to this point. And by the stories that I’ve been hearing about corona-parties or whatever they are, where people actively try to get infected so they can get immune, I think many other people don’t think about it either.
The thing is, for you to get effective immunisation to a disease, you have to produce neutralising antibodies, which prevent subsequent (in this case) viruses that you come in contact with from entering your cells in a sufficient number to produce disease. And, as far as I was able to understand from the recent research, not all patients that recover from COVID-19 have neutralising antibodies circulating in their blood, raising questions about what types of antibodies are produced (neutralising, binding, both…?) and their roles in clinical improvement and future immunisation. In this article, Derek Lowe also states that beyond knowing that neutralising antibodies for SARS-CoV-2 exist (we know they do), it’s also important to know “the details past that: where does this antibody bind, exactly, and with what affinity? What part of the viral life cycle does it disrupt?”.
As for why passports are a bad idea, I’ll leave you with a Nature article that explains the challenges of the current diagnostic tests (namely sensitivity and specificity), and also point out the “infection doesn’t equal immunity” conundrum. I think passports are not great because they’re giving out some sort of status of importance, while not truly keeping his or her bearer safe.
There are more questions than answers at this point. Maybe that’s why it’s so hard for lay people to trust science. It’s hard to deal with uncertainty, and even harder to research and understand all the background information that leads to a new piece of data—I had to do an immunology refresh to write you this letter. It’s so much easier to spin stories about a mobile broadband and a tiny, non-living entity.
FURTHER RESOURCES ON DIAGNOSTIC TESTING
While researching this week’s topic, I came across the Finddx website, where they have a section about SARS-CoV-2 diagnostic pipeline. You can play around with the filters and find out how many tests are commercially available or under development for the diagnosis of COVID-19. I found 133 commercialised rapid diagnostic tests with the CE-IVD marking, although I couldn’t filter down for Ig testing only.
And if you’re in the mood for learning more about COVID-19 diagnostics and testing, I have just the thing for you: the Foundation for Innovative New Diagnostics (FIND), the African Society of Laboratory Medicine (ASLM) and the London School of Hygiene & Tropical Medicine (LSHTM) got their heads together and produced an e-course where they talk about the role of diagnostics, molecular testing and immunoassays for COVID-19. The course is free for five weeks if you don’t need a certificate.
If you have any questions or comments about antibodies and serology tests, just leave a comment below 🙂
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