Why do some people never get Covid

How does Corona affect the brain and make it shrink?

Why do some people never get Covid, and what are the secrets of natural immunity against the Corona virus, and how does it affect the size of the brain, and why do we no longer have to worry about the transmission of the Corona virus from animals to humans?

Why do some people never get Covid?

Under the title "Why do some people never get Covid?" "The unpredictability of the coronavirus has made clear how little we know," Dr. Daniela J. Lamas, a pulmonologist and critical care physician at Brigham and Women's Hospital in Boston, wrote in The New York Times.

Why do some people never get COVID-19?  Corona, Covid-19, immunity, infographic

"While standing at the bedside in the COVID-19 intensive care unit during the first wave, I wondered why young people without specific risk factors had developed serious illnesses while their spouses and children were able to manage their symptoms at home," she added.

She pointed out that Omicron "recently invaded cities, infecting people at a much greater rate than before, yet the results of some tests for the virus continued to be negative, even if their roommate was positive."

She pointed out that "doctors and researchers around the world are now asking and trying to answer similar questions."

The doctor reviewed some data that indicate the extent to which Corona affects us is related to genes, such as:-

Firstly. According to studies conducted by Dr. Mayana Zatz - in Brazil - there is no single genetic mutation that can affect the response, and she and her research team found variants in the genes of affected people, compared to the genes of their asymptomatic spouses.

These variants affect the activity of natural killer cells, a key component of the immune system. People who have not shown any sign of infection are more likely to respond to strong natural killer cells, which can lead to a stronger defense against infection. This does not mean that all those who avoided the disease did so by virtue of these genes.

Secondly. Pediatric immunologist and geneticist Dr. Jean-Laurent Casanova from Rockefeller University, in the US, has identified a small percentage of patients with severe COVID-19 who have mutations in genes involved in virus resistance, resulting in a gap in the body's ability to defend itself against infection. . These people were otherwise healthy before they contracted the coronavirus.

But our genetic code is exactly where it all begins, In the end, our genes are only one part of the very complex story of this virus, a story that we will tell and retold in the coming years.

The secrets of natural immunity against the Corona virus

This topic was also written about by Florence Rosier in the French newspaper " Le Monde ", saying that some people were able to resist infection with the Corona virus from the beginning of its appearance, while others contract it easily.

"Since the beginning of the pandemic until now, it has been observed that some people have never been infected, despite being exposed to this risk on several occasions," she added.

As for the question about which people have the ability to resist the virus, Professor Laurent Appal, director of the Laboratory of Human Genetics and Infectious Diseases at the Imagine Institute in Paris, says: “The most interesting model is that people are not exposed to infection within the framework of the close family, as the spouses, for example, For example, one of them can be infected without knowing it, and he continues to behave normally, although his partner does not transmit the infection to him.”

In addition, another mystery relates to people who work in a job that makes them vulnerable to the transmission of the Corona virus with ease, but despite that they miraculously escaped from all the droplets and drops of human fluids that fly in the air and are loaded with the virus, and this happened even in some work environments where it was not available masks.

Is there a natural protection for these people? There are even people who have resisted infection with the Corona virus, even though their health condition makes them at risk of deteriorating.

Natural resistance to corona virus infection

According to a study published in October 2021 in the journal nature immunology , "the percentage of people who have a natural resistance to infection with the Corona virus is still unknown so far. But genetically, there are some candidate genes that determine this issue." ".

To study this phenomenon in a scientific way, the researchers first made sure that those included in this study had not previously contracted the infection without showing symptoms, and for this purpose, they were subjected to corona smear tests, and blood analysis to prove the absence of antibodies, and thus ensure that the immune system has This person has never been exposed to this virus.

Olivier Schwartz, head of the Virology and Immunology Unit at the Pasteur Institute in Paris, who is also involved in this study, says: "Infection resistance may be linked to 3 protective factors that may combine in the same person, which are genetic, immune and environmental factors."

Scientists have relied on various methods to investigate this issue, including studying the genetic differences between those who have natural immunity and those who have been infected, and the second way is to study the lifestyle and occasions that represent a risk or provide protection from infection, and the other way is to analyze the biological mechanisms that affect This issue.

Dr. Etienne Decroli, a French virologist, explains that "the human immune system, when it detects the presence of the virus early, can reduce its effect on the body. In contrast, when it is slow in the detection process, the viral load can rise dramatically and paralyze the work of the body." immunity".

So far, scientists have not identified specific genes that could be responsible for this, but Dr. John Daniel Lolliaver, co-author of this research, believes that "the issue is perhaps not related to a specific gene, but rather to several genetic variants that all overlap to determine our exposure to infection or the possibilities of deterioration." Our state of health, and each gene affects a certain stage of the disease.”

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Human acquired protection

Some scientists also believe that there is acquired protection in humans obtained from previous exposure to a virus from the Corona family, which is suggested, for example, by a scientific study published on January 10, conducted by Imperial College London starting from September 2020, when People had not yet begun to receive the vaccine, and infection rates were not high.

In this study, which included a sample of 52 people who had contact with a person close to them infected with the Corona virus, it was noted that half of this sample did not become infected, and these particular people were distinguished by high levels of immune protection provided by the T cells that the body produces when infected with the virus. Corona is of another kind, like the one that causes seasonal influenza.

That study indicated that these T cells, which remain for a long time in the human body, are able to identify the internal proteins in the Corona virus - its scientific name is “SARS Cove-2”, which makes this cellular immunity strong, and not vulnerable to retreat when mutations occur. in the spike protein found on the surface of the virus.

The author believes that these results are encouraging, given the frequent seasonal colds. But until now, the actual level of immunity that these T cells provide against the Corona virus has not been determined, which needs more research and analysis.

Study: COVID-19 can cause brain shrinkage and memory loss

An Oxford University study concluded that the coronavirus can cause brain shrinkage, reduce gray matter in areas that control emotion and memory, and damage parts that control the sense of smell.

The scientists said that the effects were seen even in people who were not hospitalized due to infection with “Covid-19”, and that further study is needed to determine whether the effect can be partially reversed and whether it is persistent in the long term.

The researchers also said in their study published on Monday and reported by Reuters that "there is strong evidence of brain-related abnormalities" in patients with "Covid-19".

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Corona leads to a shrinkage in the size of the brain

Participants in the research reported observing a "deterioration in executive functions" responsible for concentration and organization even in mild disease, with brain volumes shrinking on average between 0.2% and 2%.

The study, which was reviewed by researchers in the field and published in the journal Nature, examined changes in the brain of 785 participants aged between 51 and 81 who had their brains scanned twice, including 401 who contracted COVID-19 between the two scans. The second survey was conducted after an average of 141 days from the first.

The study was conducted when the alpha mutated MERS-CoV was prevalent in Britain and is unlikely to include anyone infected with the Delta strain.

Studies have concluded that some people who have contracted Covid-19 suffer from "brain fog" or mental fog, which includes poor attention, concentration, speed of information processing and memory.

The researchers did not say whether vaccinations against the Corona virus had any effect on the matter, but Britain's Health Security Agency said last month that a review of 15 studies found that those who received the vaccination were almost half less likely to develop long-term "Covid-19" symptoms. Compared to non-restaurants.

In a report published by the Swiss newspaper " Luton " (letemps), the author Orol Colon quoted Guenel Daoud, the lead author of the study, as saying: "We noticed that the brains of the injured participants lost more gray matter than those of the uninfected people, and these differences were observed in regions of We also identified atrophy of the brain, and the changes were greater as people got older.”

According to the writer; “These findings are very exciting, because for the first time they provide a picture of the brain before and after infection, where we can compare aging-associated atrophy with the atrophy associated with Covid-19,” said Dr. Thanks to the monitoring group.

Towards a dementia epidemic?

The writer continues her report, saying that the mechanism of action of the Corona virus in the brain is still not well understood, adding that the attachment of the virus to the olfactory mucosa receptors can reduce the sensitivity of olfactory neurons and thus reduce their signals, which was confirmed by Doctor Asal, who said that “the prolonged absence Sensation can lead to a deterioration of the olfactory nerve pathways. This is called attention deficit.

The writer said that the other hypothesis - which is better studied in severe forms of Covid 19 - is an inflammatory reaction in the brain due to the weakening of the vascular wall; In the affected areas of the brain, the functions related to smell and memory overlap, which makes specialists fear that this long-term infection could accelerate the development of neurodegenerative diseases in some patients, such as dementia.

Gilles Allali, director of the Linardis Memory Center, warned: "We may face a dementia epidemic due to the neurodegenerative processes accelerated by COVID-19."

Why do we no longer have to worry about the transmission of the Corona virus from animals to humans?

Writer Jonathan Goodman predicted in a report in The Conversation , that Omicron and any other strain that will appear after him, will become increasingly specialized in living in the human body, and thus more able to move between people. Therefore, he believes that we no longer have to worry about the transmission of the Corona virus from animals to humans.

He wrote that the "Corona-SARS-2" virus, since the beginning of its transmission between humans, had new variants that helped it transmit the infection more effectively, as this virus, in its early stage, was contagious to various animals, including cats and dogs. and bats, which many blame for the virus jumping from animals to humans.

Conditions at the marine animal market in Wuhan may have provided this virus in 2019 with a favorable environment for its development. And then we saw various strains appear in humans, such as alpha, beta, delta, and now omicron, and these are the same evolutionary steps that we can expect from a new organism trying to adapt to the host environment.

Corona virus strains that evolve in other organisms will not be able to live in the human body

Regardless of its characteristics, each new strain that emerges is more contagious and spreads than the previous one. It now appears that this virus specializes in residing in the human body.

The writer indicates that this virus appeared in 2020 in the mink, which was considered at the time as evidence of its ability to settle in diverse environments such as humans, but this discovered type did not pose a threat to human health. Recently, other signs of the presence of strains of the virus have appeared in deer in Ontario, Canada, and many more examples are expected in the future.

However, all these strains will not be able to compete with strains that have adapted to the human body such as Omicron. And just as some humans who used to live in specific environments, and have a certain diet, will face health risks when there is a drastic change in their living conditions, the strains of the Corona virus that develop in other organisms will not be able to live in the environment of the human body.