Does the new coronavirus cause a serious new inflammatory disease in a small number of children and adolescents? This is the question that concerns several countries after the recent appearance of unusual cases, in the midst of the Covid-19 epidemic.
"All of the pediatricians, resuscitators (in Europe) work together to see whether or not there is a need to make a link with the Covid-19, which I do not know yet when I speak to you", declared the French Minister of Health, Olivier Véran, Wednesday at the National Assembly.
"This is something that concerns us," assured his British counterpart, Matt Hancock, the day before on LBC radio.
"There have recently been some descriptions in European countries of children with this inflammatory syndrome, but it seems really rare," said Maria van Kerkhove, a WHO expert, on Wednesday. The organization nevertheless called on the health authorities to refer him to possible cases which would be noted in other countries.
But "the vast majority of children with Covid-19 only have a slight infection and recover completely," insisted his colleague Michael Ryan, insisting on "reassuring parents".
"We are following this issue carefully," a spokesperson for the Swiss Federal Office of Health told AFP.
The questions are all the stronger since all studies have so far shown that the severe forms of Covid-19 were extremely rare in the youngest.
The alert left this weekend in England, with a report from the public health service, NHS England.
In the process, a small number of similar cases were mentioned in France, the United States, Spain, Belgium or the regions of northern Italy most affected by the coronavirus.
On all Parisian hospitals, this represents "about twenty children," said AFP Damien Bonnet, head of pediatric cardiology at Necker Hospital for sick children.
"According to my French colleagues, there are others elsewhere," he adds, stressing however that their number in absolute terms "remains limited". The first case was admitted to his hospital "three weeks ago" and "it has been accelerating for about 8 days".
At Pope John XXIII hospital in Bergamo, in northern Italy, 20 children suffering from this type of inflammatory syndrome have been hospitalized since March 21, which is as much as in the last three years.
A shared observation on the other side of the Atlantic.
"I saw such patients yesterday and today, and my colleagues have seen them for two or three weeks," said AFP Sunil Sood, an infectious disease specialist at Cohen's children hospital in New York.
"Favorable development"
According to Professor Bonnet, these young patients are "2 to 18 years old". Dr. Sood, on the other hand, mentions "adolescents, the youngest of whom is 13 years old".
How does it manifest? "These children come with digestive, respiratory or infectious symptoms" accompanied "by a cardiac attack", answers Professor Bonnet, according to whom "most need to be helped with drugs to support the functioning of the heart".
"The children almost all evolve favorably, even if they are in a resuscitation situation initially," insists Professor Bonnet.
Likewise, all of the young patients that Dr. Sood was aware of have seen their condition improve, even if they have not all been discharged from hospital yet, and none have died.
Some symptoms suggest toxic shock syndrome or Kawasaki disease.
This disease that affects children leads to inflammation of the blood vessels (skin rashes, lymph nodes, conjunctivitis, heart problems in severe forms ...). "Every blood vessel in the body is on fire," says Dr. Sood.
But even if there is "overlap of symptoms" with the cases currently observed, there are also differences, notes Professor Bonnet.
The first of these is the age of the patients: "Kawasaki disease is primarily a disease of the small child, rather less than 2 years old, even if there are up to 4 or 5 years old. Here we see all ages. "
All this "will be clarified over time, to find out if it is a particular disease", adds the French doctor.
Tests
In all the countries where these few cases have been reported, some young patients have tested positive for Covid-19 and others negative. The causal link between the coronavirus and these inflammatory syndromes is therefore not established with certainty.
However, the conjunction of the two challenges.
"We are in the time of the Covid-19 epidemic, we see an infrequent disease becoming more frequent. That questions us," explains Professor Bonnet.
Another clue: even if the causes of Kawasaki disease are unknown, it has long been suspected that it can be "a disproportionate inflammatory reaction to a common viral infection", according to Professor Bonnet.
"The new coronavirus may have the same inflammatory response as that of other viruses in Kawasaki disease," adds Dr. Sood.
In adults, it is believed that severe forms of Covid-19 may be linked to the triggering of an overly strong immune response caused by the disease.
In all the countries concerned, specialists call for increased vigilance to better identify the cases of children hospitalized for an atypical inflammatory disease, and determine whether or not there is a link with Covid-19.
Whether or not this link exists, the appearance of these cases risks raising concerns when several countries are considering reopening schools after a period of confinement.