Why children’s immunity is more resistant to coronavirus

Even in the first months of the COVID-19 pandemic, it became clear that a new infection, for some reason that was not clear at that time, was bypassing children. And if children or adolescents become infected, then the disease in them proceeds noticeably easier than in adults.

The situation has not changed much even today – almost 2 years after the start of the epidemic. But nevertheless, some versions explaining the phenomenon of higher resistance of children’s organisms to SARS-CoV-2 have already appeared among specialists.

How do children cope with COVID-19

Despite the fact that the number of cases of COVID-19 around the world is growing rapidly, cases of infection among children, as in the first months of the pandemic, are relatively few.

According to one version, the cause of this may be the asymptomatic course of the disease in children. And because the child looks healthy, he does not have symptoms characteristic of COVID-19, parents do not go to the doctors. Therefore, cases of infection are not fixed.

In addition, children and adolescents tend to have a fairly strong immune system that prevents infection from spreading quickly. Therefore, many of them, even after infection with COVID-19, can proceed in a milder form.

Why do children get sick differently than adults?

Back in 2003, when the SARS outbreak occurred, doctors observed about the same situation as now with SARS-CoV-2. Then the infection also almost did not affect children. The least vulnerable during the epidemic were children under 12 years of age. Although almost 800 people died among adults at that time, which is about 10% of all those infected. Then the experts had not so many versions of why children get sick differently. Today there are already several.

Strong innate immunity

Recently, American scientists have also started talking about the fact that strong innate immunity can protect children from coronavirus. In particular, experts have found powerful immune cells on the mucous membranes lining the nose and other parts of the body that come into contact with microbes.

Mucous membranes are composed of epithelial, dendritic cells and macrophages, which are key elements of the immune system. These cells are coated with special proteins known as recognition receptors. When they detect a pathogen in the body, they send specific impulses to the cells. As a result, the body begins to produce the protein substance interferon, which determines the immune response. ^[1].

In another study, the German Institute of Public Health in Berlin found that children’s upper respiratory tracts are “pre-activated” to fight the novel coronavirus. There are many immune clients in the respiratory tract that perfectly recognize the causative agent of the disease. According to the researchers, this feature allows boys and girls to instantly activate their innate immunity – to produce interferons that stop the spread of the virus.

In the body of adults, these cells are much smaller. It takes about 2 days for an adult body to recognize the virus and respond to its penetration. And by this time, the pathogen has time to multiply strongly, and then it becomes harder to fight it ^[2].

These discoveries suggested that the presence of a large number of antibodies is not as important for children to resist the virus as it is for adults. In young organisms, the immune cells of the mucous membranes cope well with this task.

Research data show that healthy boys and girls have a large number of lymphoid cells (cells of the immune system) in their bodies, which, if infected with coronavirus, make it easier to resist the disease. As we age, the number of these cells decreases. ^[3].

Another possible reason why children are less susceptible to coronavirus is the ACE2 receptor. More precisely, the number of these receptors in the body. The SARS-CoV-2 virus enters the human body through airborne droplets. Once on the mucous membranes of the nasopharynx, the pathogen connects to special ACE2 receptors, after which the virus multiplies and spreads throughout the body. So, studies have shown that children have fewer ACE2 receptors than adults, which means that the risk that the virus will “take root” and begin to multiply is lower. ^[4].

Easier to adapt to new diseases

The fact that children’s organisms adapt more easily to new diseases than adults is not new in scientific circles. That is why many of the diseases, such as chickenpox or measles, are easily tolerated by children, while in an adult a similar infection can cause serious complications. It is quite possible that something similar is happening with COVID-19 – children’s organisms have adapted to a new disease for themselves and more easily resist the pathogen.

Absence of chronic diseases

The most dangerous coronavirus is for people with a weakened immune system and with a history of chronic diseases. One of the most common complications of COVID-19 is pneumonia, which most often occurs in patients with diabetes mellitus, cardiovascular pathologies. Among boys and girls, serious chronic diseases that cause complications and undermine immunity are quite rare. And this may also be one of the reasons why young patients suffer from the disease asymptomatically or in a mild form. By the way, the same is observed in the case of ordinary influenza: people with chronic diseases are more at risk of complications than children.

Quarantine

Some attribute the lower incidence of COVID-19 among children to the quarantine measures that are in place around the world. In particular, as soon as the number of cases in the region overcomes an alarming mark, children are transferred to distance learning. In this way, contact between large groups was prevented and, as a result, the risk of infection was minimized. In addition, adults are always more attentive to protecting the health of children, which can also be regarded as one of the potential factors for lower COVID-19 infection among children.

However, research in this direction continues. But the fact that the children’s immune system reacts differently to infections than the bodies of adults is already clear.