A month after the first wave of the covid pandemic broke out, pediatricians across Spain began to detect cases of a syndrome so strange that it had no name. It was already becoming clear that SARS-CoV-2 causes serious illness, especially in older people or people with previous illnesses. That is why it was so rare to find children who between four and six weeks after being infected, when they were completely healthy, fell ill with continued fever, generalized inflammation and other symptoms that put their life in serious danger.
“They were 8-year-old kids. to 14 years that they arrived with a strong abdominal pain and fever of several days ”, remembers Alberto García-Salido, pediatrician of the ICU of the Hospital Niño Jesús in Madrid. “They did not have respiratory symptoms like the adults. The first thing we thought about was appendicitis; later, that it was an inflammatory syndrome due to a bacterial infection ”, he says.
The patients also had red eyes, weakness, continued fever, nausea, vomiting and low blood pressure. In a few days, the situation could be complicated by forcing these children to enter the ICU. Although this condition could attack the main organs, most had complications in the heart. At first it was thought that it could be Kawasaki disease, an ailment in children with no known cause that inflames blood vessels. Later it was understood that it was a new condition related to SARS-CoV-2. It was a set of signs and symptoms rather than a specific disease, what doctors know as a syndrome.
"We are facing a very, very rare condition" Alfredo Tagarro, pediatrician at Infanta Sofía
The World Health Organization gave its name to the new ailment in May after the growing list of cases in the United Kingdom, the United States, France or Italy: Pediatric Multisystemic Inflammatory Syndrome (MIS-C, in its acronym in English). Since then, many doctors have launched into the investigation of this strange syndrome, but its causes and the factors that determine that a child undergoes an infection with hardly any symptoms and can become ill a month later to the limit of seeing their life in danger are not yet clear. .
"We are facing a very, very rare condition," warns Alfredo Tagarro, pediatrician at the Infanta Sofía Hospital in Madrid and coordinator of the national pediatric registry on this new syndrome in Spain. In a study that he has just presented at the Congress on Retroviruses and Opportunistic Infections, his team has analyzed data from 52 Spanish hospitals. Since the beginning of the pandemic, only 90 cases of MIS-C have been detected in our country, which represents 0.02% of all infections registered in people between zero and 18 years of age, explains Tagarro.
The MIS-C It is the most serious pediatric complication related to the coronavirus that has been recorded in this pandemic and the main cause of admission to the ICU in children. Among the 90 cases there have been two deaths, both with previous illnesses
The latency period between the infection and the arrival of the syndrome is highly variable, it can reach up to four months later, explains Cinta Moraleda, pediatrician at the Hospital 12 de Octubre in Madrid and co-leader of the study. “We are trying to find out why this happens, what is the immune mechanism . At the moment we think that the SARS-CoV-2 infection works like the trigger of a weapon that triggers the immune response in patients who have a predisposition ”, he highlights.
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contagion. The prevalence of this strange syndrome in Spain is similar to that of other countries. There are so few cases in Spain that it is very difficult to draw statistically valid conclusions, not even if it affects more boys than girls (62% of the cases are boys). All the complications detected seem to respond to the same cause: an uncontrolled reaction of the immune system caused by the virus. It is something very similar to what happens in older patients, the so-called cytokine storm, which causes severe COVID and can end the life of the patient.
Children are known to be infected with coronavirus the same way as adults, but suffer much less from the symptoms of covid. The body's response to infection has two large arms. One is innate, the first line of response, and the other is adaptive, because it includes specialized molecules such as antibodies and lymphocytes capable of neutralizing SARS-CoV-2 and eliminating infected cells. In children the innate response is much more active than in adults, which may explain why they stop the infection before it can cause complications or even mild symptoms.
Postcovid syndrome in children is similar to that already known in adults
In MIS-C this innate immune response is defective. Instead of effectively fighting off the virus, the body produces widespread inflammation that can attack the lungs, liver, eyes, brain, and especially the heart. It is possible that the virus remains in an organ and resurfaces after a few weeks. There is data to support this possibility. "One month after infection, only 15% of children have a positive PCR," explains Tagarro. "In contrast, among children at risk of MIS-C that percentage rises to 45%," he adds.
Doctors treat this syndrome with corticosteroids to quell the exacerbated immune response and with intravenous immunoglobulin containing antibodies. "Now that we know what we are facing as soon as we establish a link with the coronavirus, we begin to apply the treatment and the response is very fast, with a clear improvement in just 12 hours," explains García-Salido. "In the vast majority of cases the syndrome is cured and does not leave sequelae," he highlights.
The syndrome in children is similar to the postcovid complications that are already known in adults . In any case, the associated mortality is very low, less than 2% of cases, recalls Federico Martinón-Torres, pediatrician at the Hospital Clínico Universitario de Santiago de Compostela. The situation, he says, was much worse in the first wave than in the second and third, when the medical community is already on notice. "Now we walk with the fly behind the ear," he explains. "But although it is a very rare syndrome, it highlights the importance of vaccinating children as well," he concludes.
Tagarro's team has developed an online system to calculate the risk of suffering from this syndrome. It is based on common markers, such as a high concentration of inflammatory proteins in the blood, a lack of white blood cells and anemia.
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