They’re all over the news lately – and soon, they’ll be all over the world. But how do antibody tests actually work? And what do they mean for the global battle against COVID-19?

Today, we’re going to break it all down as simply as possible. You’ll learn what an antibody test is and how they work, plus a bit about how they may impact our COVID-19 recovery. It’s still early days, but there have been a number of exciting breakthroughs already… we’re making big steps forward!

What is an antibody test?

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Antibody tests are special tests that detect antibodies in a person’s blood. These tests are also known as “serological tests” or “antigen tests” (which may be slightly different, but generally have the same goal: find out if you’re immune to a given disease).

They usually come in the form of a device that pricks your finger, extracting a small blood sample. This device is sent to a lab, where the blood is screened for antibodies.

As you may know, antibodies are our body’s natural defense system. You can think of them like specially trained agents. They’re trained to fight a single disease, and they do it really well. But they take time to “train” – and if the infection is dangerous, your body might not have enough time. (That’s why we use vaccines – they “train” antibodies so they’re prepared in advance when a “real attack” comes!)

So! Unlike a COVID-19 test, which checks for the presence of the disease itself, you want to be positive for an antibody test – it likely means you’re immune to the disease. (But it’s not guaranteed – more on that in a moment!)

How do antibody tests work?

First, it’s important to know that there are two types of antibodies:

  • IgM antibodies, which show up early in an infection (and help fight it)
  • IgG antibodies, which generally show up once you’ve recovered (to prevent it coming back)

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For a while, we did not have accurate versions of these tests. However, two companies have recently developed highly accurate tests: Swiss company Roche and American company Abbott Laboratories. Both of the new COVID-19 antibody tests look for both of these types of antibodies, making them both comprehensive and highly accurate.

In fact, these new tests have 100% sensitivity – which means that if you have COVID-19 antibodies, the test will catch them every single time. (There is a very small chance of a false positive, but zero chance of a false negative.)

It’s no wonder that world governments are seeking millions of these tests. They can provide critical information in a time of uncertainty. However, we do need to take them with a grain of salt… because (like everything else in this crisis) nothing is certain. Which leads us to the big question:

Do antibodies protect you against COVID-19?

So, it would be great if we knew this was the case… that would mean that anyone who tests positive could freely go about their business without worry.

But sadly… we simply don’t know for sure if antibodies prevent future COVID-19 infection – and even if they do, we don’t know how long they’ll last.

Theoretically, antibodies should protect you. So if you test positive for COVID-19 antibodies, that probably means you can’t get infected again soon. But since COVID-19 is still new, we don’t know if this is true… or how long your immunity would last.

Right now, only a small percentage of people being tested have antibodies. We don’t know if everyone will get them – or if they provide a reliable way to know who’s immune.

That said, antibody tests are still very helpful right now – they provide a bit of crucial information in a time of great uncertainty.

How are antibody tests different from the standard COVID-19 tests?

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Since the beginning of the pandemic, we’ve been using a test called the RT-PCR test (the test you hear about on the news). This test checks for the virus itself. However, these tests are often inaccurate… and once someone recovers, they won’t likely show signs of the virus. That makes it difficult to know how many people have had the disease overall.

That’s why experts are pushing for antibody (and antigen) tests. Although they may not be able to predict who is immune, they will give us a LOT more information about the spread of the virus. This allows us to better protect ourselves as we re-open the economy.

Why are antibody tests important in fighting COVID-19?

First off, widespread antibody tests would help workers get back to work sooner. If we know someone has antibodies, we know it’s extremely unlikely that they will be contagious OR catch COVID-19. The more people who have antibodies, the more general immunity we have in the population (in theory).

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Antibody tests also help us understand the general spread of the virus. Right now, we only have single cases and stories to work from regarding widespread (or “herd”) immunity. But once we start seeing big data about infection and antibody rates, we will learn about the risks of a new outbreak happening again.

Finally, having the antibody tests gives us peace of mind as we all slowly get back to “normal” – whatever that turns out to be. Ideally, we will soon learn more about the antibodies themselves to determine how “safe” they make you. But for that, only time will tell.

Conclusion: Antibody tests are an important step forward, but the waiting game continues

We hope you enjoyed learning a bit more about these tests that are all over the news lately. We think they’re a very positive sign, even despite their faults. The more information we have, the better we can work together to solve this crisis and start looking forward again.


Psst… we love hearing from our readers! If you have any questions or comments about this article, please let us know in the comments below. We’ll see you next week!


8 comments on “Innovations Explained: How Do Antibody Tests Work?

  1. Nancy Closson on

    I have never had Covid but participate in The Corale Embarc Study that Cedars Sinai is conducting. They regularly test my blood for antibodies and I always test positive for the IgG antibodies but have not ever had Covid. I did have the Moderna shots & both boosters.

  2. Norman Huber on

    I am a regular doner of blood platelets and after getting my first Moderna vaccine the antibody test the Red Cross was using was positive as were subsequent tests after my second shot, until the Red Cross quit using the tests. I was so glad to have the feeling of confidence that I have some protection from at least serious illness.
    As someone who spent 17 years assigned to Walter Reed Army Medical Center working mostly on the research side, I appreciate the hard work of the scientific researchers who have worked under the pressure put on them by the politicians, news media and public demanding answers which were not yet certain. All the answers are still not certain and will not be for years.

  3. nat on

    they say after six months that the shots aren’t as effective, they kind of wear off slowly. that’s why they are giving booster shots now. in comparative studies those who took hydroxy and those who didn’t felt better around the same time anyway.
    If you tested positive why would you need an antibody test? you know you already had it.
    I would consider a booster shot eventually though.

  4. William Lobel on

    I had two Pfizer vaccine shot over eight months ago. I spite of that I tested positive for Covid two weeks ago and I certainly had the disease. I isloatedfor10 day eve though my symptoms disappeared in 5 days ( three days after I started taking hydrochloroquine which I now think of as the real answer to the virus.

    Should I get a antibody test to be sure I have antibodies in my system? If yes, which test should I take and when should I take it?


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