October 22, 2020

The first line of defense of the immune system ‘rid’ the children of Covid-19


A girl enters her school in Tenerife.

A girl enters her school in Tenerife.

The unlearned immunity, the one that is acquired at birth, or in other words, the innate immune response, is what is ridding children and young people from suffering from Covid-19 in its most serious form. The first line of defense of the immune system is the one that is helping these and other asymptomatic people to contain the advance of the virus, since it is responsible for releasing the macrophage cells, which really play a leading role when it comes to finishing with the virus.

But not everyone has that kind of immunity. And it is the main reason why this coronavirus is capable of crossing the first line of defense and reaching directly into the trenches, devastating its path and driving the immune cells that begin to shoot each other crazy. Sometimes it is simply because troops are more tired, have little training, and ignore the infection until it is too late, as is the case with older people. In others, despite having young, strong and vigorous soldiers, they have forgotten to give them the attack instruction, which is why they are left behind and by the time they realize the situation, there is no turning back. This is what happens when the immune response has a genetic defect in the TLR (Toll-like receptors) molecules that are responsible for recognizing pathogens.

But that SARS-CoV-2 barely affects the little ones also has to do with the exhaustive training to which their defenses are subjected. “The vaccination program in children works like a gym for the immune system,” explains immunologist Yvelise Barrios, from the Hospital Universitario de Canarias (HUC). The expert says that this frenzied activity during the earliest stages of life is what allows your body to be more prepared to respond to a pathogen such as SARS-CoV-2. “In addition, the smallest are continuously exposed to different coronaviruses, with which it is believed that a type of cross immunity can be generated,” insists the expert.

In a digital meeting to explain the relationship between the immune system and the different behaviors of the disease in terms of its development, the expert pointed out that “some cases of young patients with serious and even fatal disease have been published where it has been shown that some of the factors involved in this response are genetically altered, and therefore, it has left these individuals defenseless against this aggression ”. For the doctor, it is necessary to transfer, especially to the youngest, these types of examples, since “you can have the mutation and not know it because it has never influenced your life.”

The need for the immune response to occur rapidly has to do with the progression of the disease itself, which is divided into two stages. In the first, the virus begins to replicate and it is necessary to use antivirals to try to mitigate the effect. The dangerous thing happens later, when the virus spreads through the body because that is when the aggression that it produces hyperstimulates the immune response, in an effect called cytokine storm, causing the most important injuries. “In this phase we use immunosuppressive treatments and the most used are corticosteroids,” he said and insisted on the importance of supplying it at the right time, since it can generate the opposite effect if it is prescribed before the cytokine storm occurs.

Regarding the immunity generated by Covid-19, the expert recalled that, although the level of antibodies progressively decreases in a person who has undergone the disease, there is more and more evidence that the immune response remains lodged in the T cells. This means that even if its blood levels are low, the body will “remember” the pathogen if it is infected again. “That is exactly what we are looking for through vaccines, that a cellular immunity is generated”, concluded the expert.

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