I-TEAM | Natural COVID immunity vs. vaccine: What’s the difference?

Published: Oct. 28, 2021 at 6:38 PM EDT
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AUGUSTA, Ga. (WRDW/WAGT) - You’ve probably heard or at least thought about the differences in your immunity to COVID if you caught it naturally versus what protection the vaccine can offer you. Researchers around the world are working to find out how long immunity lasts in different cases. And since it’s time to start thinking about your booster shot, our I-Team took your questions to the experts.

If “Schoolhouse Rock” got it right — three is a magic number. And shot number three is exactly what elderly and immunocompromised patients are counting on to keep them safe right now.

But what does “safe” mean? Researchers are working to find that magic number and it starts with antibodies.

Antibodies are Y-shaped proteins produced by our immune system after we’re exposed to a disease. These proteins help your body recognize the threat, and be better prepared the next time they face it.

You can scrub the internet for scientific studies and not find what a “good” level of antibody protection is right now. So we went to the experts to find out more.

“To be honest, there is no study yet that tells us exactly what the level is the maximum, minimum — it is still going on. However, what we know — as time goes by, our immune system — the protection goes down,” Dr. Babak Baban said.

Baban is an immunologist and the associate dean for research at Augusta University. He studies antibodies for a living.

Right now there’s a lab test you can take called a semi-quantitative antibody test. It’s a blood test that counts your antibody levels. Our I-Team had volunteers share their test results with us and we brought them to Baban to sort through.

Five different tests — one a 50-year-old who contracted COVID naturally about a year before taking the test. Their results were 85 au/mL, so in a milliliter of their blood, the test detected about 85 units of COVID antibodies.

Another — a much younger patient, 18 years old, who also contracted COVID naturally about a year before taking the test. No vaccine. Their results — higher at 410 units.

We tested one more unvaccinated patient. This person had COVID more recently, 10 months ago, is 49 years old, and only tested positive for 157 units.

So, you can see what researchers are dealing with. The body’s response can depend on your age, other diseases and conditions, medications you’re taking, the load of the virus, and more.

“It is not standard. It is not uniform. It depends on so many different factors,” Baban said.

Which is why the vaccine is so important. Experts aren’t saying you won’t get any immunity by catching the COVID-19 virus naturally; they’re saying the level of antibody immunity is wildly unpredictable.

“With the vaccine, we know exactly how much of the designed protein goes inside of the person and we can measure it,” Baban said.

Researchers also know natural immunity does not last as long. A study recently published by Yale researchers found the risk of reinfection with COVID for an unvaccinated person goes up to 50 percent after 17 months. The findings show an unvaccinated person should expect to be reinfected with COVID-19 every 16 to 17 months on average.

“When you get the antibody based on the infection, it stays for a shorter period. The half life is less than what you specifically introduce to the immune system,” he said.

So, what does the antibody test show for vaccinated patients?

I-Team’s Laura Warren took the test. She is 32 with no known COVID infection, and was fully vaccinated back in April six months ago. Her levels show 1,093 units.

I-Team’s Liz Owens also took the test. She caught COVID back in March and has been fully vaccinated for about two months now. Her levels are the highest the test will detect. Greater than 2,500.

“So this test made me feel a lot better that my body is still producing antibodies. Why is the FDA telling me not to interpret the results of my test as an indication of a specific level of immunity or protection?” said Warren.

Well, for a number of reasons. For one, they aren’t sure what different levels mean for different people. Two the test is under emergency use authorization and isn’t fully FDA approved and probably the most important reason is number three.

“What the test shows — it is an indicator, but it is not the most determinate factor,” said Baban.

The immune system is complex. And maybe one of the most important levels of protection that isn’t as easily tested is your cellular immunity. That could be activated by the vaccine, without many antibodies showing up in a test.

“Vaccination isn’t only for antibody production — it’s for the whole immune system — protection,” he said.

So bottom line, if you take this test, experts say use the results as a piece of the immunity puzzle. Not the full picture.

You can take the test through LabCorp at the Walgreens in Evans. You can sign up before you go online here: https://patient.labcorp.com/covid-19-antibody-test. They take a little blood from your arm. But, make sure to request the semi-quantitative test. There are other tests that will just say ‘yes’ or ‘no’ to whether antibodies are present in your blood, but this test will give you a count.

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