COVID-19 Variants: Here's How The Vaccines Still Protect You

The coronavirus shots don't just produce antibodies -- they also create T-cells. Here's what those are, and why they matter.
The vaccine can do more than just create antibodies against COVID-19. T-cells also matter when it comes to protection from the virus and its new variants.
Andriy Onufriyenko via Getty Images
The vaccine can do more than just create antibodies against COVID-19. T-cells also matter when it comes to protection from the virus and its new variants.

It seems like each day there’s more bad news about coronavirus variants.

There are headlines claiming the variants are becoming deadlier, and stories warning that some variants could escape the vaccines, imprisoning us in a never-ending pandemic. With every step forward — like how millions of Americans are being vaccinated daily — it feels as though the variants send us two steps back.

A growing number of infectious disease experts are now saying the variant narrative has spiraled out of control ― at least when it comes to vaccines. Some people are even trying to get boosters on their own for their vaccines; the Centers for Disease Control and Prevention recently announced there is no need to do this yet.

Yes, there are several variants circulating, and it’s true that some appear to be more transmissible. Yes, more new variants are emerging. Yes, we’re still in a pandemic and we need to continue to exercise caution. But there’s currently no reason to think the variants will render our vaccines completely useless, infectious disease experts say.

Our immune systems are extremely complex, and even if some parts of the immune system don’t respond as robustly to the variants after vaccination, it’s not going to give up on us that easily. Here’s why:

The COVID vaccines help you produce antibodies ― and they trigger another immune response that also fights the virus.

Much of the research regarding immunity against COVID-19 (which can be achieved either through vaccination or natural infection) has looked at antibodies. These little fighters go after the coronavirus and prevent it from binding to cells in our body and creating an infection. Some lab studies have found that antibodies don’t do as good of a job fighting variants, which has raised fears that the vaccines might not be able to keep us safe.

But antibodies don’t tell the full story. When people say antibody levels dip ― and therefore protection against COVID-19 disappears ― “this is totally wrong,” said Jay Levy, a virologist and professor of medicine at the University of California, San Francisco.

The immune system is very complex, and in addition to antibodies, there’s a whole other aspect, known as the cell-mediated immune response, that’s just as important, if not more. This part helps create something called T-cells, which are crucial to preventing infections. The COVID-19 vaccines don’t just generate antibodies; they also prompt your immune system to produce T-cells.

“T-cells are the main line of defense against the virus,” said Monica Gandhi, an infectious disease specialist with UCSF. T-cells can identify many different parts of the coronavirus (some studies say up to 52 parts) and get rid of any cells that are carrying the virus. The cell-mediated immune response can also help our systems produce new antibodies if need be. Mutations or not, T-cells will still be able to detect the virus and jump into action. “Your immune response is very complex, very robust, and very in-breadth against multiple parts of the virus,” Gandhi said.

So, why aren’t we all talking about how awesome T-cells are? They’re really hard to measure, Gandhi said, whereas measuring antibodies involves a simple blood test. But researchers have looked at the cell-mediated immune response in people who were either vaccinated or had COVID-19, and the findings are exciting.

For one thing, all of the vaccine clinical trials found that participants produced strong T-cell responses after vaccination, according to Gandhi. There’s also evidence that the variants probably aren’t going to have a very meaningful effect on the immunity we get from being fully vaccinated. Two recent studies found the T-cell response was unaffected by variants, and another paper found that while some antibodies diminished against variants, our T-cell response held up just fine.

When it comes to COVID-19, a robust T-cell response is the difference between a mild infection and serious disease, research shows. The cells can’t always prevent an infection, but they may be able to clear it out quickly so you don’t get badly sick. If you get vaccinated, “you don’t need to worry about getting infected — or if you do [get infected], that you will have any serious illness,” Levy said.

“Your immune response is very complex, very robust, and very in-breadth against multiple parts of the virus.”

- Monica Gandhi, infectious disease specialist, University of California, San Francisco

How long will these T-cells last?

From the looks of it, even if antibody levels wane over time, T-cells are probably going to keep us protected against variants for a while, especially when it comes to severe disease, according to Gandhi.

The coronavirus would have to change pretty dramatically to totally escape recognition from the cellular immune response and render our vaccines useless. “The cellular immune response seems to be a little more diverse, or a little more inclusive, so it can pick up small, little changes that a variant might have and still handle it,” Levy said.

The cell-mediated immune response can also have a lengthy memory. Researchers have evaluated the blood of people who had the SARS coronavirus in 2003, and found their T-cell immunity has persisted for up to 17 years. The T-cell response has similarly held up in people who’ve been vaccinated against measles for 34 years and counting.

COVID-19 is a little over a year old, but early evidence suggests our T-cells will last, though it’s unclear exactly how long. Some experts say we may need booster shots eventually, and scientists are already working on those. But given the durability of our cellular immunity, many infectious disease experts think boosters, at least in the near future, will be unnecessary.

Researchers will continue studying how components of the immune system — antibodies, T-cells and everything in between — deal with the coronavirus over time, but we know the immune system is robust and durable when it comes to fighting viruses.

So, if you’re vaccinated, the next time you read a chilling headline about a variant, take a breath for now and think of the T-cells. “Know that the T-cells work against the variants and you are OK,” Gandhi said.

Experts are still learning about COVID-19. The information in this story is what was known or available as of publication, but guidance can change as scientists discover more about the virus. Please check the Centers for Disease Control and Prevention for the most updated recommendations.

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