They explain why Covid-19 manifests itself differently in children

R. Ibarra




Children’s immune systems respond differently to SARSCoV-2 than adults. This is stated by a work recently published in “Science Immunology” which would thus explain why the infection manifests itself differently in children compared to adults.

The new study has analyzed the cases of patients with multisystem inflammatory syndrome in children, a rare but serious complication of Covid-19 in children, and you have seen distinctive immune features of Covid-19 not seen in adults.

Citrons show that cases of children with Covid-19 they are much smaller than in adults. However, it is increasing.

According to a SEPAR report, the cases of children infected by the coronavirus in Spain barely represented the 1% of the total in the first wave, in which 1,400 cases were diagnosed, of which 20% or 25% required hospitalization and only 52 cases were admitted to the ICU.

But in the second hello, at the end of August, the proportion of children infected with SARS-CoV-2 it was already 6% of the total in Spain and, at the end of September, 66,000 cases of infected children had already been registered, which represents 12% of the total cases reported by the Ministry of Health. These data are consistent with the epidemiological evolution of other countries, such as U.S, where COVID-19 cases in children are between a 12 and 15% of the total.

The document indicates that currently most cases correspond to asymptomatic children or with milder symptoms than those of adults, who have a good evolution and of which only 1% require hospitalization.

Despite this, more serious but very rare inflammatory syndromes have emerged, such as multisystemic inflammatory syndrome, which is characterized by generalized inflammation, a variety of symptoms ranging from fever to vomiting, and insufficient blood flow throughout the body that can provoke a shock.

The work now published by Science Immunology shows that, although the immunological landscape in pediatric Covid-19 was similar to that of adults, patients with this syndrome experienced increased activation of a subset of CD8 + killer T cells that patrolled the blood vessels; In addition, all pediatric Covid-19 patients had a greater B-cell response for a longer period of time than that seen in healthy adults.

Killer T cells

To learn about the immune characteristics of multisystem inflammatory syndrome, researchers at the University of Pennsylvania (USA) analyzed immune responses in blood taken from 30 pediatric patients hospitalized infected with SARS-CoV-2, 14 of whom were diagnosed with multisystem inflammatory syndrome.

They then compared the results of this analysis with samples from adult Covid-19 patients, recovered adults, and healthy individuals.

Patients with multisystem inflammatory syndrome had patterns of T cell decline and activation similar to adults with severe Covid-19, they also had robust activation of a subset of killer T cells that patrol and interact with the vasculature to control viral persistence.

Thus, they verified that although patients with multisystemic inflammatory syndrome presented patterns of decrease and activation of similar T cells adults with severe Covid-19, also had aa robust activation of a subset of killer T cells that patrol and interact with the vasculature to control viral persistence.

This characteristic was not observed in pediatric Covid-19 patients without multisystem inflammatory syndrome or adults.

Furthermore, while children with another syndrome, acute respiratory distress caused by Covid-19, had sustained immune activation, overall immune activation in patients with multisystem inflammatory syndrome decreased over time, in parallel with clinical improvement.

All pediatric Covid-19 patients had substantially elevated B-cell frequencies compared to healthy adults.

These findings, they conclude, portray the variability in immune responses to SARS-CoV-2 across ages and patient populations and may help design treatments for severe Covid-19 in children.

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