A lot of very smart people are quite alarmed by the WHO’s comments that there is no evidence of immunity for survivors of COVID-19.
This is leading some people to panic: If nobody becomes immune then how do we ever beat this thing. We’ll never have a vaccine! This is the end!
So, let’s drill down a little bit into what we know and don’t know.
No Evidence of Immunity
Factually, this statement is true. We can’t be sure that recovered patients are immune until we have observed an extended period of, well, people not getting sick again.
That extended period simply hasn’t happened yet.
But what the WHO is really saying is this: We don’t have enough proof to rely on antibody tests as proof of immunity.
What they’re saying is that we shouldn’t start issuing immunity passports or using high levels of antibodies in a population as proof herd immunity has been attained. Instead, we should just look at…well…how many people are getting sick.
So, how does this all go together?
How do Antibodies Work?
Our immune systems produce programmable cells called antibodies. Antibodies are unique to an infection and they are designed to home in on the pathogen when it shows up again and kill or deactivate it (Viruses are not alive, so it’s not technically correct to say “kill” in this context).
This is called our adaptive immune system. We also have an innate immune system, which tries to hold off pathogens we don’t recognize. Our skin is part of our innate immune system, and it’s very effective; this is why most viruses enter through our mouth or nose, where there’s no skin to get in their way.
The adaptive immune system starts to get to work when the innate immune system notices that something’s gotten in. Antibodies are created to specifically identify and track the infection, then killer cells go after them.
Here’s the issue: Our immune systems are a bit messy. They aren’t well-honed machines. Rather, they generate a bunch of potential antibodies, watch to see which ones work, then make more of them.
Kind of like how we’re doing trials of all kinds of drugs right now.
Why Might Somebody Not Generate Antibodies?
We do know that you need to generate antibodies to be immune. Some people who recover from COVID-19 don’t have any antibodies. This means they’re definitely not protected.
These patients are generally younger. So how does this happen? It happens when the innate immune system works really well.
If your innate immune system fights off a pathogen before your adaptive immune system gets in on the act, no antibodies. This is pretty common with colds; it’s why you can catch a cold from a coworker, give it to a family member, then catch the same dang cold again from the family member. SARS-CoV-2 is related to a number of viruses that cause common colds.
In other words, if your immune system works too well then the pathogen can come back for a second or third round. The good news is that you’ll probably fight it off again. The bad news is you aren’t protected and the next round may be worse.
Why Might Antibodies Not Mean You’re Immune?
So if you have antibodies you’re immune? Sadly, not so fast. There are a few factors to consider:
- Your immune system might not have made particularly good antibodies. Antibodies are a bit of an experiment, and it’s possible to fight off an infection, develop antibodies, but have those antibodies be useless when it comes back.
- Your immune system stops making antibodies after the threat. This is why immunity wears off for some viruses.
- The virus may mutate. This is why you need a flu shot every year. It’s likely we’ll be needing our COVID shots periodically too, although the exact length of time is unknown.
- The test might not be specific enough. Antibody tests might, for example, pick up on antibodies you made against a different coronavirus…that cold you had right before Christmas that made you thoroughly miserable. While it’s possible there may be some cross-immunity from other coronaviruses, that’s yet another thing we don’t know.
(Tests may also give false negatives).
What Do Experts Say About Likely COVID-19 Immunity?
The good news is that based off of animal testing, experts believe that most people who recover from COVID-19 will have some measure of immunity. It might not be 100% and it’s pretty certain not to be lifelong. As the pandemic phase comes to an end, we’ll get the virus down to a simmer and slowly more people will become immune.
The expert guess is that, based off of very similar viruses, immunity will probably last 2 to 3 years for people who do get a good antibody response.
Another promising note is that very early indicators are that treatment with convalescent plasma does indeed work, and this proves that the donors in those cases are generating good antibodies.
What About a Vaccine?
If not everyone gets antibodies, then what does this say about vaccine development?
Relax. The thing about vaccination is we’re putting the vaccine where the immune system will notice it. There’s a reason flu shots go into the muscle (or under the skin, but that kind was discontinued because everyone hated it — it might have to come back for COVID). A vaccination is a direct and specific message to your immune system “Please make antibodies against this.”
There is, of course, absolutely no guarantee we’ll get a good vaccine against COVID-19, but the questions about immunity don’t make it less likely. They will, however, effect how often we have to get our COVID shots.
In other words: Don’t panic. But also don’t assume that because you had COVID-19 symptoms you’re now immune. It’s likely, but it’s far from a guarantee.