If you get COVID-19 and you recover from it, does that mean you’re immune to the virus? And even if you were to become immune, how long would that Covid 19 immunity last?
Now we’re still waiting on studies to really give us definitive answers to these questions and will do Covid 19 Comparison with other Viruses.
But in the meantime what can help us understand COVID-19 immunity, is thinking about our body’s responses to other infections. and it as an immunity spectrum.
So here are some examples along that immunity spectrum to help us better understand where COVID-19 be compared to other Virus diseases.
1. Varicella-zoster virus – (ChikenPox)
On one end of the spectrum is Varicella-zoster virus, the virus that causes Chickenpox and you might remember from your own childhood, that if you get Chickenpox once you usually develop a lifelong immunity to it and you don’t get it again.
This kind of lifelong immunity happens because of antibodies. Something you’ve probably been hearing loads about recently.
Antibodies are proteins made by our immune system that protect us from harmful things.
Those can be infections like viruses and bacteria, but also toxins and cancer cells.
With Chickenpox, your body churns out antibodies that are in it for the long haul and it also has cells that are ready to make more antibodies.
Should you meet the virus again, you can get exposed to viruses through natural infection or this is a preferable way, you get immunized.
Meaning you get a vaccine that introduces your body to a weakened version or a dead version of a virus, so that your body knows what to recognize and it mounts a solid immune response that stops you getting sick.
And if you didn’t get sick with Chickenpox as a kid, you get two shots of the vaccine that gives you longterm immunity.
Now, some people who have a weakened immune system can get Chickenpox a second time, and in fact, our bodies are never able to get rid of the virus totally.
It stays latent inside our nerve cells and in around one third of people, the virus reactivates later in life and causes Shingles.
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So how does COVID-19 compare to Chickenpox?
Obviously the ideal situation would be that you get COVID-19 once and that’s it. You’re immune forever to the virus that causes the disease.
Unfortunately, this doesn’t seem that likely. And here’s why.
There were early studies showing that when people recover from COVID-19 they do have antibodies in their system, but because this is such a new infection.
One, we’re not sure how long those antibodies hang around for and two, there are some reports of those antibody levels dropping really low, just a few weeks after infection.
2. Whooping Cough
Here’s another example, Whooping cough, this is caused by a bacteria, and usually if you get infected once that immunity lasts from 4 to 20 years.
So quite a big range. Because immunity fades over time. The CDC recommends you get vaccinated against Whooping cough, but even with that, you need to get booster shots.
Those are shots that you get your initial vaccinations to make sure you stay protected over a period of time.
So even if we do develop a successful vaccine for COVID-19, maybe that vaccination scenario will be similar to Whooping cough where you get your initial doses of vaccine, but then you have to get booster shots as well.
3. Swine Flu
So here’s our next example. H1N1 Influenza, also known as Swine Flu.
Studies have shown that immunity to H1N1 can last anywhere from 2 years to 10 years.
This is a strain of flu that caused a pandemic in 2009 but now circulates pretty regularly alongside other common flu strains.
And with the flu the reason that we’re getting new flu shots every single flu season, is because flu strains are changing.
And so literally every summer in the Northern hemisphere, scientists are racing to predict which flu strains are gonna hit us.
And what kind of vaccine they need to make for that specific flu season.
Some experts predict that SARS-COV-2 will follow that same path as H1N1.
Meaning it causes a terrible pandemic at first but then circulates much more like a regular virus after the fact.
Now when it comes to figuring out where the new Coronavirus might fit on the immunity spectrum.
4. SARS Coronavirus
Our best bet might be to compare it to the original SARS Coronavirus.
SARS stands for: Severe Acute Respiratory Syndrome, and that’s caused by the Coronavirus that emerged in 2002 and caused a pandemic in 2003.
Infecting more than 8000 people around the world. Studies of SARS patients who recovered, showed their antibody levels peaked around 2 to 4 months and that they offered protection for 2 to 3 years.
So is this a timeline that we might consider for SARS-COV-2. Well, there are some studies that show that when our bodies are infected with SARS-COV-2, we produce what we call a neutralizing antibodies.
And these can stick around and offer protection for a couple of weeks. That’s what the early studies are showing. But clearly a couple of weeks is a ways off from two to three years.
The glimmer of hope might be that there’s so much genetic similarity between SARS-COV-2, and SARS-COV-1.
5. Common Cold
Another good comparison we have right now is to the four Coronaviruses that caused the cold immunity to these seasonal Coronaviruses starts fading just after a few months and within a year.
Most people are vulnerable to reinfection, meaning it won’t go away. It will still infect people, but it won’t cause such serious disease and it won’t cause so many infections.
So that’s a possible scenario that we might see with the new Coronavirus.
So on the other end of the immunity spectrum compared to where we started is HIV. People with HIV do develop antibodies to the virus, but either those antibodies don’t stick around for long, or the virus has really cunning ways to hide from the antibodies.
That’s partly because HIV is constantly mutating every time it’s replicating inside the body that makes the virus a moving target for our immune system.
Some good news on the COVID-19 front, is that this Coronavirus does not seem to mutate anywhere near as frequently as HIV mutates.
That means it stays a much more consistent and it means we have far less of a moving target. And because of that, some experts are saying that reinfection with the new Coronavirus could be less likely just because the virus isn’t changing so much.
So our immune systems recognize it and know how to fight it. But it’s way too early to be saying that reinfection is unlikely just because of how new this virus is and how much we’re learning day to day.
So we don’t know exactly where COVID-19 is gonna fit along this immunity spectrum. But let’s say you get infected with the virus and it does give you antibodies that hang around for months, maybe even a year or so.
In that scenario, you can start thinking about herd immunity as one way out of the pandemic. Herd immunity is when a significant proportion of the population has become immune to a disease.
Either through becoming infected or being vaccinated, and when herd immunity is achieved, it stops a disease spreading like wildfire through a population.
That exact proportion of people that need to be immune to a disease in order to achieve herd immunity. It varies from pathogen to pathogen and it depends on how infectious a microbe is.
We’re still a ways off from thinking about herd immunity as our way out of the COVID-19 pandemic for at least two reasons.
The first being that we just don’t know yet how long those antibodies will hang around for and how protective they’ll be.
But second, because for herd immunity for COVID-19, you’d need between 50% to 70% of a population to become immune.
And we don’t have a vaccine yet, meaning we’d have to see a lot of people just get sick from the virus and that’s not a feasible way out of the pandemic.
And finally, there’s that question about antibody testing.
If we get studies that show us how protective antibodies are to this virus and how long those antibodies stick around.
Then in that case, widespread antibody testing could be really useful, especially if it’s a quick fingerprint blood test to help us understand who is immune, for whom is it safe to go back to work and how quickly could we start resuming normal activities?
But even if a large number of people have been infected, recovered, and have immunity, it’s still not gonna trigger a sudden reopening of society.
There’s gonna have to be a gradual peeling back of containment measures like sheltering in place to make sure that we’re constantly guarding against a second wave and against future outbreaks. And that’s gonna be our reality until we have a vaccine.