Are People Naturally Immunized or Tolerant to COVID-19?

More than 2 years since the COVID-19 pandemic, Most Americans have some immunity to the virus — By vaccination and / or infection. However, there are some rare cases in which certain unvaccinated people appear to have been able to dodge the virus despite repeated exposure to the virus. This raises the question of whether some people may simply be immune or resistant to COVID-19, even if they do not have the virus or vaccine.

Scientists are trying to understand if such resistance to COVID-19 exists and how it works. According to researchers, studying these cases may help develop new vaccines and treatments for the disease. Life of over 990,000 Americans..

“It’s hard to speak publicly, because when you say things, people say,” Oh, I’m not infected yet, so it must be me. ” In fact, you may not be infected. Shane Crotty, a virologist and professor at the Lahora Institute for Immunology, told Yahoo News.

Crotti said he and other experts are talking cautiously because the topic is still under study and there is no clear answer yet.

“I think what you don’t really know is a dangerous suggestion, so you risk getting a life-threatening illness. Most of us. [scientists] I tried to be very careful. … These don’t seem to be what we know, but they are possible, ”he added.

A brief potential explanation is that some people who didn’t have a COVID were lucky, Crotty said. It may also be protected by actions such as wearing a mask properly and avoiding certain situations at risk of getting sick.

“We rarely know unless the COVID was obtained by a household member, so it may not have been exposed or may have been exposed at low levels,” said Infectious Disease Epidemiology at the University of Texas Public School. Said Catherine Troisi. Houston’s health told Yahoo News. “The other explanation I think probably accounts for a significant proportion of these cases is that you have it. We know that it is often asymptomatic. You I’m not sick, so I don’t know you had it, “she said.

But scientifically speaking, why some people may be much more resistant to the COVID-19-causing virus SARS-CoV-2 than others. Said that there are two potential explanations that could explain. One idea is that due to the existing immunity to other coronaviruses that cause the common cold, the virus can be rapidly cleared before it reaches detectable levels.

There are more than 200 common cold viruses, four of which are coronaviruses, which account for about 30% of all common cold infections. According to the Centers for Disease Control and PreventionAt some point in life, most people become infected with one or more of these seasonal coronaviruses.

“The main idea is that there is a T-cell response that happens to occur in response to a particular coronavirus that certain people have previously had, which may provide some protection that others do not happen to have. That’s it, “crotti said.

T cells are an important part of the immune system and help fight some viruses. Antibodies, such as vaccines and antibodies obtained from previous infections, attack when the virus invades the body, while T cells prevent the virus from multiplying and causing it when it invades the body. Acts as another line of defense. Severe illness. Scientists call these T cells “cross-reactive,” which appear to be effective against various types of coronavirus.

Crotti and his colleagues One of the first to publish research on this topicScientists analyzed blood samples from people who had been infected with SARS-CoV-2 and compared them to blood samples from people who had never been infected with the virus.

“All laboratories around the world have shown that these cross-reactive T cells are present, and depending on the measurement method, they are present in about 50% of people,” said Crotty. ..

another British healthcare professional study The one announced in November last year had similar results. This study evaluated a group of UK healthcare workers who were exposed to the virus but did not develop COVID-19 during the first wave of the pandemic. Researchers have found that the presence of cross-reactive memory T cells among some participants contributes to “rapid elimination of SARS-CoV-2 and other coronavirus infections.” bottom.

But Crotti said this is something scientists need to continue their research. “It’s a very difficult study, so there’s no research that can just nail it down,” said the professor. He and his team are determined to find some answers. They have enrolled people who have never been infected or vaccinated and plan to monitor them over the long term.

He said these T cell response studies play an important role in the development of new COVID-19 vaccines.In fact, there are already different groups Scientists working on shots specifically targeting T cells..

Our current vaccines are designed to produce antibodies that recognize and bind to proteins on the surface of the virus, such as the spike protein, which is part of the virus that helps the virus attach to B cells, a type of white blood cell. It is designed. cell. In the presence of antibodies, the virus cannot infect cells. However, the main challenge was frequent mutations in the coronavirus spike protein. This benefits the virus by avoiding antibodies that are no longer recognized.

Some experts believe that T cell vaccines may be more effective because they can recognize other parts of the virus that may not mutate at the same rate as peplomer proteins. Vaccines that target T cells may also provide long-term protection against serious illness, as studies have shown that antibodies decline months after vaccination.

Another potential explanation for COVID-19 resistance is that some people may have innate immunity. This means that there are genetic factors that protect them from SARS-CoV-2 infection.

Neville Sanjana, an assistant professor of biology at New York University and a core faculty member of the New York Genome Center, has studied the potential genetic factors underlying COVID-19 resistance. He states that one of the interesting places that may provide some answers is the virus invasion mechanism. In the case of SARS-CoV-2, this is a specific protein that allows the virus to infect human cells called the angiotensin converting enzyme 2 or ACE2 receptor. ..

Mutations in the ACE2 receptor make it difficult for the virus to enter, according to Sanjana. Virus resistance to these types of mutations has already been demonstrated against other viruses such as HIV.

“We know that we have an entry receptor similar to that identified in SARS-CoV-2, but it’s a different gene,” he said. “In the case of HIV, the virus that causes AIDS, the invading receptor is CCR5, and we know that some people naturally have mutations that remove CCR5 … and this effectively immunizes them. I’ll leave it to you, “he added.

In addition to studying possible mutations in the entry receptor, scientists are looking at other genetic mutations throughout the human genome, Sanjana said.

“The human genome contains about 20,000 genes, and which of these genes affects important cells, such as the airway epithelium and lung cells, which we consider to be the pathway of SARS-CoV entry. I really don’t know if it could give them. -2 “, he added, adding that some of those genes may make people more or less vulnerable to COVID-19.

Joint project COVID Called Human Genetic Effort Studying thousands of people in different countries, it may reveal why some people are not infected with COVID-19, or why certain people get sick and others are not. I’m looking for a genetic variation of.

Sanjana said these studies are important for the development of next-generation therapies.

“Most of the treatments we have, whether remdesivir or paxlobid, act on the virus. They target the virus. They target the viral genes,” he said. .. “If you understand what the major host genes are … you might imagine that what we can do is probably design other therapies that target those genes.”

Thumbnail photo on cover: MR.Cole_Photographer via Getty Images

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