Before Covid-19 vaccines were available, Covid-19 antibody testing was the only way of telling … [+]
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If you are looking for a single magical number to tell whether you can be more lax on Covid-19 precautions, sorry, but the level of antibodies in your blood is not going to provide it. Antibodies aren’t like One Direction T-shirts. Having more shouldn’t necessarily give you more comfort. It’s not that simple.
The role of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) antibody testing has evolved since Covid-19 vaccines became widely available. Back in 2020, such testing was the only way of telling whether you had any type of protection against Covid-19. But that hasn’t been the case in the U.S. since December 2020 when vaccination began. ,That hasn’t stopped some people from continuing to make misleading claims about what such tests can tell you. After all, there are, surprise, surprise, people out there attempting to make money off of the pandemic and in some cases trying to scam you every which way. As they say, grifters gonna grift. So you’ve gotta be careful about what you hear and do.
Of course, just because someone offers an antibody test doesn’t mean it is legit. So before you get any such testing for any reason, first make sure that the test at least has emergency use authorization (EUA) from the U.S. Food and Drug Administration (FDA). Check and make sure that the test is on the FDA’s EUA Authorized Serology Test Performance list. For example, something named the awesomesauce vegan glow up antibody test would not be on this list. Also, make sure that the spelling of the test name coincides with what’s listed on the FDA website. For example, “A butt” test is not going to be the same as an “Abbott” test.
These tests are called serology tests not because they have anything to do with the actor from the movie Scott Pilgrim vs. the World. Otherwise, they would have been called Michael Cera tests. Instead, in this case, serology refers to what’s in your blood serum, the liquid portion of your blood. These are test that look for antibodies in your blood serum as opposed to any other body fluid. So if someone asks for your urine or your semen you may be undergoing the wrong type of test. There are two general types of SARS-CoV-2 antibody serology tests: qualitative ones that simply tells you whether antibodies are present in your blood and quantitative ones that give a level of antibodies in your blood.
Even if you can get a legitimate SARS-CoV-2 antibody test doesn’t mean that you should necessarily go ahead with the testing. Sure, there will probably no significant physical harm in getting such an antibody test. It’s not as if someone will be implanting a microchip or magnets into your body when they take your blood for the serological test, right? However, the big question is whether the test will even tell you anything useful. After all, the words “blood test” and “a whole lotta fun” usually don’t go together.
Keep in mind that the Centers for Disease Control and Prevention (CDC) website specifically says that “antibody testing is not currently recommended to assess for immunity to SARS-CoV-2 following Covid-19 vaccination, to assess the need for vaccination in an unvaccinated person, or to determine the need to quarantine after a close contact with someone who has Covid-19.” In other words, the CDC is saying don’t rely on antibody testing to assess your level of protection against Covid-19.
Why might such testing be unreliable? Well, first of all, antibodies are by no means the only way that your immune system may protect you against Covid-19. Focusing on antibodies would be like focusing on only one player in a football team’s defense or simply the violins in an orchestra or just Niall Horan in One Direction. Your B lymphocytes (white blood cells) can produce antibodies that can block and inactivate the virus. of your immune system, are only one mode of protection. But your B cells, T cells, and other other cells can do a whole lot of other things too such as secreting chemicals that make it more difficult for the virus to do its damage or chomping up virus infected cells. Simply having antibodies doesn’t necessarily mean that all of the other modes of immune protection are working and vice-versa.
Second of all, it’s not clear what level of antibodies may be enough for adequate protection, whatever “adequate protection” means. Like the number of garden gnomes in your front yard, higher levels of antibodies may be better. A study published in the New England Journal of Medicine back in October 2021 showed that health care workers in Israel with higher levels of antibodies tended to have lower rates of breakthrough Covid-19 infections. However, unlike the pairs of underwear that you wear at a time, there isn’t a magical threshold, above which you are adequately protected.
Thirdly, over time your immune system can generate different types of antibodies against the spike protein of the SARS-CoV-2. If you recall, the spike protein is what studs the surface of the Covid-19 coronavirus and makes it look like the end of one of those BDSM maces, like the ones that you keep hidden under your bed. Soon after encountering either the spike protein from vaccination or the whole virus from natural infection, your B cells begin manufacturing IgM antibodies. These are part of the early immune response with antibody levels rising quickly within the first several days, peaking fairly early before dropping. By comparison, levels of IgG antibodies, also produced by B cells, rise slower, peaking potentially several weeks after the spike proteins or viruses are gone from your body. IgG antibodies assist with longer term protection. Levels of IgG may stay elevated for an extended period of time (weeks to months), long after IgM levels have plummeted. The trouble is a given antibody test may not distinguish between these different types of antibodies and thus not give you a better sense of their status.
Finally, the number of antibodies generated from either Covid-19 or Covid-19 vaccination may differ from person to person. If you haven’t figured it out yet, people may differ in many different ways. For example, what may work for Brad Pitt may not work for you. So don’t go comparing your antibody levels with that of your significant other or your friends or your fierce rival or some stranger at the doughnut shop.
All of that being said, antibody tests are not completely useless. They can still provide useful information depending on the circumstances. For example, antibody levels can tell you whether you’ve been vaccinated against Covid-19. Antibodies to the S protein will likely be present if you’ve been either vaccinated or previously infected. Antibodies to N protein may be present if you’ve been previously infected. Of course, in most cases, there are other ways to determine this such as remembering that you were vaccinated. Typically, you wouldn’t have gotten vaccinated by a bunch of ninjas in the middle of the night while you were asleep. And getting vaccinated while drunk is not advised.
Nonetheless, you may want to check whether you actually got vaccinated when there are questions about the storage and administration of the vaccine. Or perhaps your immune system is weaker due to the medications that you are taking, the other medical conditions that you may have, or your age. An antibody test can help double-check whether your immune system did respond to the vaccine.
Such blood serologies can have broader public health applications as well. Scientists and public health officials can use this information to track what percentage of the population may have already been exposed to the SARS-CoV-2 and thus make recommendations as to when certain Covid-19 precautions should be relaxed or tightened. This would depend on people’s test results being made available to public health officials and politicians actually listening to scientists and public health officials, neither of which may be the case.
All in all, don’t use antibody tests to decide what to do about face mask wearing, quarantining, other social distancing measures, and ventilation or whether to get vaccinated. Instead, try to maintain at least three types of Covid-19 precautions at all times and follow public health recommendations regardless of what your antibody levels are. Having had natural infection is not a replacement for vaccination. As I have covered previously for Forbes, studies have shown that vaccination may offer much better protection than natural infection, especially since natural infection can be so variable in its course and severity and the immune response.
As with many things in life, your immune protection against Covid-19 is complex. A single number can’t tell you much unless it’s something like the number of marmots in your bed.
