Coronavirus Reinfection Cases: Everything We Know – And Important Missing Clue

President Trump he Resistant to COVID-19 An isolated report has come up about reinfection, but what is the truth about immunity to COVID-19?

until today, 6ReleaseCase COVID-19 reinfection, and various other unidentified accounts from around the world.This is a relatively small percentage Millions of people Do I need to worry because I know I’m infected? To deselect this puzzle, you first need to consider the immunity immunity.

How immunity works

When we are infected with a pathogen, the immune system reacts quickly to contain the threat and try to minimize the damage. Our first line of defense is from immune cells known as innate immune cells. These cells are usually not enough to eliminate the threat. The threat is the more flexible “adaptive” immune response, where lymphocytes act.

There are two main types of lymphocytes. B lymphocytes that make antibodies and T lymphocytes that contain cells that directly kill bacterial invaders.

Antibodies are often used to show a good adaptive immune response because they are easily measured in the blood. However, over time, antibody levels in the blood decrease, which does not necessarily mean that protection is lost. We hold some lymphocytes, our memory cells, who know how to deal with the threat. Memory cells have a very long lifespan and are ready to patrol our body and take action when needed.

Vaccines work by making memory cells without the risk of fatal infection. In an ideal world, creating an immunity is relatively easy, but it’s not always easy.

Our immune system has evolved to handle a wide variety of pathogens, but these bacteria have also evolved to hide from the immune system. This arms race means that some pathogens, such as malaria and HIV, are very difficult to deal with.

Infectious diseases spilled from animals (zoonoses) can also be completely new and difficult for the immune system. The virus that causes COVID-19 is such a zoonotic disease, Bat..

COVID-19 is caused by betacoronavirus. Some betacoronaviruses are already common in human populations-the most well-known cause of the common cold.Immunity to the viruses that cause these colds is not Healthy But with immunity to more serious conditions, Mars Sars, More durable.

According to previous data on COVID-19, antibodies can be detected 3 months after infection, but as with Sars and Mers, antibodies gradually decline. with time..

Of course, antibody levels are not the only indicator of immunity and do not tell us about T lymphocytes or our memory cells. The viruses that cause COVID-19 are structurally similar Sars, So perhaps you could be more optimistic about a more durable protective response-you’ll see the time. So how much do you need to worry about reporting reinfection with COVID-19?

How worried should we be?

A handful of case reports of reinfection with COVID-19 do not necessarily mean that immunity is not occurring. Test issues can cause some reports, as “viruses” can be detected after infection. recovery.. The test looks for viral RNA (the genetic material of the virus), and viral RNA that does not cause infection can be excreted from the body even after the person has recovered.

Conversely, false-negative results occur when the sample used in the test contains insufficient viral material to detect. For example, the virus is at very low levels in the body. Such obvious negative consequences may explain the short interval between the first and second infections. Therefore, it is very important to use additional means such as viral sequencing and immune indicators.

Reinfection can also occur in the immune system, but this is usually mild or asymptomatic because the immune response protects against the worst effects. Consistent with this, most verified cases of reinfection reported asymptomatic or mild symptoms. However, one of the latest validated cases of reinfection (which occurred only 48 days after the initial infection) actually showed a more serious reaction. Reinfection..

What is the cause of the second exacerbation of symptoms? One possibility is that the patient did not initiate a strong adaptive immune response in the first round and the initial infection was largely contained by the innate immune response (the first line of defense). One way to monitor this is to evaluate the antibody response, as the type of antibody detected tells us something about the timing of infection. Unfortunately, antibody results were not analyzed in the initial infections of recent patients.

Another explanation is that different strains of virus caused the infection and subsequently affected immunity. Gene sequencing showed differences in viral strains, but it is unclear if this is comparable to altered immune perception. Many viruses share structural characteristics, allowing an immune response to one virus to protect against similar viruses. It has been proposed to explain the lack of symptoms in infants who frequently catch colds with betacoronavirus.

However, Recent researchAlthough not yet peer-reviewed, it turns out that the defense against the cold-causing coronavirus is not against COVID-19. In fact, antibodies that recognize similar viruses can be dangerous, explaining a rare phenomenon called antibody-dependent enhancement (ADE). ADE occurs when an antibody promotes viral infection of cells with potentially life-threatening consequences.

However, it should be emphasized that antibodies are only one indicator of immunity and there is no data on T lymphocytes or memory cells in these cases. These cases emphasize the need for a standardized approach to gathering critical information to reliably assess the threat of reinfection.

We are still learning about the immune response to COVID-19 and all of the new data has helped us solve this challenging viral puzzle. Our immune system is a powerful ally in the fight against infection, and only by unleashing it can we hope to eventually defeat COVID-19.

Sina crack shank, Professor of Biomedical Sciences, University of Manchester

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