Have you never had COVID? Your T cells may hold the key to defeating the virus – El Financiero

Studies have shown, for example, that while omicron infections offer some immunity against delta, omicron is able to evade antibodies from past infections with other variants and vaccines.

Current surveillance techniques have also likely grossly underestimated the number of cases, as more people test for COVID at home and do not report the results.

“It is almost impossible to measure protection,” said Andy Pekosz, a virologist at the Johns Hopkins Bloomberg School of Public Health. As cases rise again in many regions more than two years into the pandemic, studying those who have not yet contracted COVID has become just as critical as studying those who have. Experts say people with so-called “super” immunity who appear resistant to the virus without vaccination may have answers to important questions about why certain people get so sick and others don’t.

Examining these cases could also help inform the development of vaccines and therapies less vulnerable to viral mutations. “It’s basically about defining what the best case scenario looks like, which can also help identify what’s wrong with those who don’t control the virus,” said Leo Swadling, an immunologist at University College London.

It may be hard to believe that at this stage of the pandemic so many people have not yet gotten sick.. Perhaps people were asymptomatic and never knew they were infected or, despite exposure to the virus, simply never tested positive.

But even half of the population getting COVID is actually an extraordinary number of infections. The Spanish flu of 1918 is estimated to have only infected 25 percent of the US population at the time, despite causing a large number of deaths.

Early in the pandemic, Swadling set out to find out more about the lucky few who didn’t get sick. “We were particularly interested in people who are exposed to the virus, but who bring it down very quickly, shedding the virus before it can replicate to detectable levels and before it induces an antibody response,” Swadling said.

“It can help us better understand which immunity is best to protect against re-infection.” Swadling, along with colleagues in London, published a study in the journal Nature last November that evaluated to a group of UK health workers during the first wave of the pandemic.

They found evidence that some of the healthcare workers exposed to the virus were able to get rid of it even before they produced COVID-specific antibodies.

It turned out that for those people, exposure to other human coronaviruses, such as those that cause cold-like symptoms, had helped their bodies fight off the new coronavirus..

This is because T cells, a critical part of the body’s immune response, were able to recognize and attack genetic elements from previous seasonal coronaviruses that were also present in SARS-CoV-2..

That meant their bodies could attack the new virus without producing new antibodies specific to it. Notably, the T cells those health care workers produced targeted a different part of the virus than the T cells in people who have a detectable COVID infection.

Swadling said that while the T cells produced by both vaccines and a detectable COVID-19 infection target the spike protein of a frequently mutating virus, the T cells of these health care workers targeted the internal machinery of the virus.

The researchers call these T cells that appear effective against different coronaviruses “cross-reactive.”

“We identify new parts of the virus that we can put into a vaccine to try to improve it,” Swadling said. These improvements, he said, could make vaccines better at preventing infections, more effective against new variants, and more protective for immunocompromised people.

Immunity to a virus occurs when the body is able to recognize a pathogen and effectively defend itself against infection or disease. Antibodies, such as those acquired from a vaccine or previous infection, attack a virus as soon as it enters the body.

T cells act as another line of defense, working to stop the spread of infections and the development of disease once the virus has entered the body.

Vaccines of mRNAs, like those made by Pfizer and Moderna, work by training the body to safely produce antibodies without infection, but they also stimulate the production of T cells and B cells.

That’s why vaccines effectively prevent hospitalization even when they don’t completely prevent infection; Even when the antibodies have decreased, the T cells are still there to help fight an infection more quickly.

The study authors proposed that the T cells they found, those that target the virus’s internal machinery, may offer better protection against emerging variants because of their ability to attack a key part of the virus less vulnerable to mutation than its counterpart. spike protein.

They theorize that targeting those areas of the virus could make the injections more effective. As laboratories work to develop a single injection that offers broader protection against any variant of COVIDAt least one company, Gritstone Bio Inc., is looking to put Swadling’s theories to the test.

Others have reached conclusions similar to those of Swadling and his colleagues. One study found that in households where some people remained COVID-free despite exposure, those people also seemed protected by T cells from prior exposure to coronaviruses.

Another study from January found that some children who did not develop antibodies to COVID also had cross-reactive T cells, which may be part of the reason children typically have milder symptoms.

Knowing how many people have this heightened immune response is extremely difficult to assess. Some people may have managed to avoid the virus with continued caution or just plain luck. But perhaps more important than knowing how many people fall into this category is the information about immunity that can be gleaned by studying what sets them apart.

“T cells are very long-lived, so we may not need repeated vaccinations,” Swadling said. Studying the superimmune, he said, can help us against omicron, and any future variants of concern.

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