Children With Severe Inflammatory Syndrome Had No Symptoms of COVID-19

Following the publication of the largest U.S. analysis of the syndrome, MIS-C, which may strike young people weeks after coronavirus diagnosis, doctors advised pediatricians to be cautious.
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According to the largest review of cases in the United States to date, several children and adolescents who acquired the unexplained inflammatory syndrome that may occur many weeks after contracting the coronavirus never showed classic Covid-19 symptoms at the time of their infection.

In over 1,000 cases where evidence on why they got sick from their original Covid-19 infection was available, researchers from the Centers for Disease Control and Prevention discovered that 75 percent of patients did not have those symptoms. However, they became ill enough to be sent to the hospital with Multisystem Inflammatory Syndrome in Children two to five weeks later.

According to the report, "most MIS-C illnesses are believed to result from asymptomatic or mild Covid-19" accompanied by a hyper-inflammatory reaction that tends to arise when the patients' bodies have developed their optimum amount of virus antibodies. Experts are also uncertain why certain young people, as well as a limited number of adults, respond in this manner.

Since Covid is too common in population and children frequently have asymptomatic illness as their original Covid infection, primary-care pediatricians may have a high index of suspicion for it, according to Dr. Jennifer Blumenthal, a pediatric intensivist and pediatric infectious disease specialist at Children's Hospital of Philadelphia.

The researchers looked at 1,733 of the 2,090 cases of the syndrome reported to the Centers for Disease Control and Prevention in January.

The results suggest that, despite its rarity, the condition can be deadly. Only patients who were admitted were included in the C.D.C.'s records. About 90% of those children had symptoms affecting at least four organ functions, and 58 percent received treatment in intensive care units.

Many people had serious heart problems: more than half had low blood pressure, 37% had cardiogenic shock, and 31% had cardiac failure, which meant their heart couldn't pump enough blood. According to the report, patients who did not have Covid-19 symptoms had a slightly higher rate of cardiac attacks than those who had original coronavirus symptoms. A higher proportion of patients who were originally asymptomatic ended up in intensive care.

Dr. Roberta DeBiasi, head of infectious diseases at Children's National Hospital in Washington, D.C., who was not interested in the report, said,
“Even the kids with severe MIS-C, who were in the I.C.U. — the vast majority of them did not have a preceding illness that they recognized,”.

The research presented the most comprehensive demographic and regional profile of the syndrome to date. Around 34% of the cases were African-American, and 37% were Hispanic, showing how the coronavirus has overwhelmingly infected members of those groups. According to the writers, as the pandemic progressed, the percentage of white patients rose, eventually accounting for 20% of all cases. Patients of Asian ancestry made up just over 1% of the total.

The male-to-female ratio was approximately 58 percent overall, but it was not consistent for all age classes. The youngest population — newborns to age four — had nearly equal percentages of boys and females, and the male-to-female ratio grew with age, reaching more than two-to-one in the 18-to-20 group.

The overwhelming majority of the patients (nearly 86%) were under the age of 15. According to the report, children under the age of five have the lowest chance of major cardiac problems and are less likely to need intensive care. Shock, low blood pressure, and myocarditis were slightly more common in patients aged 10 and over (inflammation of the heart muscle).

“I think that’s similar to what we saw with Covid, that the older kids seemed to have more severe disease,” Dr. DeBiasi said.

“And that’s because what makes people really sick from the Covid is the inflammatory aspect of it, so maybe these older kids, for whatever reasons, make more inflammation, whether that’s in primary Covid or MIS-C.”

Despite this, many of the younger patients had cardiac attacks. In the newborn to four-year-old age range, 36% had low blood pressure, 25% had shock, and 44% were admitted to the intensive care unit.

Any of the less frequent heart conditions related to the condition, such as coronary aneurysms and fluid accumulation, were seen in patients of all ages in the study. Rashes and red eyes were more frequent in children under 14, while chest pressure, shortness of breath, and cough were more common in those over 14. Around two-thirds of all patients had stomach pain and vomiting.

There were 24 deaths recorded, with people of all ages involved. Patients with MIS-C is mostly previously stable, and slightly more likely to be healthy than the comparatively limited percentage of young people who became chronically ill from original Covid infections, according to physicians and experts.

Just 265 of the 1,075 patients with details about their original Covid infection had symptoms at the time. They were much more likely to be older, with a median age of 11 compared to 8 for those with asymptomatic Covid infections.  But that could be because “younger children can’t express their concerns as well,” said Dr. Blumenthal.