Your Body’s Rescue Immune System Remembers COVID Virus, Research Finds


CHICAGO (WGN) – We talk a lot about antibodies when it comes to post-COVID-19 infection and vaccinations, but there is another critical immune response that plays a role in protecting against COVID, and it lasts a long time after that the antibodies decrease, potentially extending vaccine power.

Since the early days of the pandemic, anthropologist Dr Thomas McDade and his co-researchers have used Chicago as a field study, looking for antibodies in samples sent to their laboratory at Northwestern University.

“We found that about 20% of people in fall 2020 were exposed to (COVID),” McDade said.

This was the first discovery of the bloodstains. COVID cases ranged from mild to severe. And now, most of the study participants have been vaccinated, giving researchers a key opportunity to measure the effectiveness of the injections.

“We have samples from before they were vaccinated. We got samples after we got that first dose of vaccine and samples after the second dose, ”he said.

Overall for all groups, when the team measured again two months after their second dose, antibodies had decreased by 20%, a normal process seen with other types of vaccination.

“It’s normal to generate a lot of antibodies as a result of a vaccine or natural infection,” McDade said. “It is also normal for these antibodies to decrease over time.”

But, luckily, human immunity isn’t just about antibodies. We have a built-in backup system that remembers the virus long after our first line of defense has waned. It’s called cellular immunity, and it’s based on what’s called T cells and B cells – the same cells that help us fight other viruses and even cancer.

“When they see it again or something like it, they will increase the production of new antibodies and new cells that will fight the virus very quickly and very effectively,” McDade said.

Those who had previously had mild or asymptomatic infections did not respond strongly to the first dose of the vaccine. This is probably because they experienced low viral loads during their natural infections – in other words, not enough virus to imprint a memory on the immune system.

“They generated a neutralizing response that was about 50% of what we want it to be. The same goes for people who had never been exposed to the virus before. It took two doses of the vaccine for everyone to have full protection, ”McDade said. “Many people who have had COVID in the past assume that they are now immune and do not need to be vaccinated.… Our studies show that if you have ever been infected with the virus that causes COVID-19 , you cannot assume that you have a high level of natural immunity.

In contrast, people who have had moderate to severe cases of COVID-19, and likely higher levels of the virus in their bodies during their illness, “responded very strongly to the first dose of the vaccine,” McDade said.

So, do we need boosters? For the immunocompromised, McDade said yes. For otherwise healthy people, McDade said more people with the first few doses would be better.

“I think for the general population, for most people, we will all be better off if more people get the first few doses of the vaccine rather than everyone getting a third who have already had the first two,” a- he declared.

Even with the delta variant in circulation, McDade’s study shows that the vaccine holds up when it comes to protecting against serious infections and hospitalizations.

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