Why are more children hospitalized for COVID-19 around the world

Globally, more than 5.9 billion doses of COVID-19 vaccines have already been administered worldwide. But the Delta variant continues to progress and has become predominant in many countries. In this context, unvaccinated girls and boys are more affected. In countries like the United States, with 55% of the population having a full diet, child and infant deaths are more poignant. While, Scientists are rushing to find out what happens to the immune systems of children who develop severe cases of the COVID-19 disease.

“It is very difficult to see children in pain,” said Dr. Paul Offit, an infectious disease expert at the Children’s Hospital of Philadelphia, United States, which – like other pediatric hospitals across the country – has been inundated with patients. infected with the coronavirus. . From the increase in hospitalizations to the development of prolonged COVID-19, which is the syndrome with different symptoms that can appear after the acute phase of infection, children can be strongly affected by Covid-19.

According to the American Academy of Pediatrics (AAP), Almost 26% of Covid-19 infections recorded in the week ending September 16 were in children. Doctors diagnosed more than 225,000 cases in children in the same week, bringing the total number of Covid-10 infections in children under 18 to 5.5 million since the start of the pandemic, with at least 534 deaths. “After declining in early summer, child cases have increased exponentially, with more than 925,000 cases in the past four weeks,” the AAP said in a statement.

In Spain, where 76% of the population has the full vaccination schedule, there is an infection rate of 91.21 people per 100,000. The situation fluctuates about 60 points between those who currently have more cases and those who have it. have less. Children under 12 lead the way with 127.86 positives according to last Friday’s notification.

The increase in COVID-19 cases in children adds to the urgency of an issue that has puzzled scientists throughout the pandemic: What keeps most children from getting seriously ill? And why does this protection sometimes fail in some children?

One of the studies published in the journal JCI Overview It was led by Betsy Herold, a scientist at the Albert Einstein College of Medicine in New York. He found that children have particularly strong mucosal immunity. They pointed out that boys have mucous membranes that act as the layered “stone walls” that protected medieval towns from invaders. They’re made up of epithelial cells – which also line many internal organs – that coexist with dendritic cells and macrophages of the immune system, according to Dr. Herold.

The protein-coated epithelial cells act as sentinels. When they detect something strange, like a new virus, they alert cells to start releasing proteins called “interferons,” which help coordinate the body’s immune response.

As, another discovery on COVID-19 in children was recently published in the magazine Natural biotechnology by scientist Roland Eils and his colleagues at the Center for Digital Health, part of the Berlin Institute of Health in Germany. They found that children’s upper respiratory tracts are “pre-activated” to fight the coronavirus. Their airways are filled with sentinel cells, some of which are excellent at recognizing the coronavirus.

This presence allows children to immediately activate their innate immune systems, releasing interferons that help stop the virus before it can become established, Eils said. In the changes, adults have far fewer sentinels under surveillance and take about two days to respond to the virus. By the time these cells are activated in adults, the virus may have multiplied exponentially and control becomes much more difficult.

When innate immunity fails to control a virus, the body can turn to the adaptive immune system, a second line of defense that adapts to each unique threat. The adaptive system creates antibodies, for example, adapted to each virus or bacteria that the body encounters.

Although antibodies are one of the easiest elements of the immune response to measure and are therefore often cited as indicators of protection, children do not seem to need as much to fight against Covid-19, specifies the Dr Herold. In fact, research shows that children with Covid-19 have fewer neutralizing antibodies than adults. Because children usually clear the coronavirus so quickly, it prevents the body from triggering an excessive inflammatory response that can lead to serious illness.

Research also shows that healthy children have large reserves of a type of pacifying cell called innate lymphoid cells, which help calm an overactive immune system and repair damage to the lungs, said Dr. Jeremy Luban, professor at the University of Massachusetts School of Medicine. As it grows, the number of these pacifying cells decreases.

The question is, what happens when the immune system fails in the face of a coronavirus infection. Among the tentative answers, research suggests that some children have stronger innate immune systems than adults because they have suffered many recent respiratory infections, in his early years. This can prepare your immune system for further attacks. But according to Dr Eils, Newborn babies have not lived long enough to prepare their immune systems for infection. Even young children may not generate a strong immune response.

Other reasons that could influence the development of severe conditions in childhood are related to diseases or syndromes that children already have before being infected with the coronavirus. Between 30% and 70% of children hospitalized with Covid-19 in the United States have been found to have underlying conditions that increase their risk, such as Down syndrome, obesity, lung disease, diabetes, or immunodeficiencies. Premature babies are also at greater risk, as are children who have had cancer treatment.

Two months after the Delta variant wave, hospitals in the southern United States are diagnosing more children with multisystem inflammatory syndrome, which is caused by acute coronavirus infection. The more serious effects of multisystem inflammatory syndrome (MIS-C) in children usually go away within 6 months.

Boys with MIS-C tend to have milder or asymptomatic infections, but get sick about a month later: they develop symptoms such as nausea, vomiting, rash, fever, and diarrhea. Some people develop blood clots and dangerously low blood pressure. According to the Centers for Disease Control and Prevention, more than 4,661 children have been diagnosed with MIS-C and 41 have died.

An explanation provided by Lael Yonker of Massachusetts General Hospital and her team suggests that viral particles can escape from the gut into the bloodstream, causing a systemic reaction throughout children’s bodies.

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