New report first to detail COVID-19 link to rare inflammatory disorder in children

A new detailed analysis from the epicenter of the Italian novel coronavirus (COVID-19) outbreak published in The Lancet describes an increase in cases of rare Kawasaki-like disease in young children, adding to similar reports from New York in the United States and South East England in the United Kingdom.

Doctors in the Bergamo province of Italy described a series of 10 cases of young children with symptoms similar to a rare inflammatory disease, Kawasaki disease, appearing since the COVID-19 pandemic arose in the Lombardy region of Northern Italy.

The study authors carried out a retrospective review of patient notes from all 29 children admitted to their pediatric unit with symptoms of Kawasaki disease from January 1, 2015 to April 20, 2020. Only 19 children had been diagnosed with the condition in that area in the past five years, but there were 10 cases this year between February 18 and April 20. The latest reports could represent a 30-fold increase in the number of cases, although researchers caution that it is difficult to draw firm conclusions with such small numbers.

Eight of the 10 children brought to hospital after February 18, 2020 tested positive for the SARS-coronavirus-2 virus (SARS-CoV-2) in an antibody test. All the children in the study survived, but those who became ill during the pandemic displayed more serious symptoms than those diagnosed in the previous five years.

Kawasaki disease is a rare condition that typically affects children under the age of five. It causes blood vessels to become inflamed and swollen. The typical symptoms include fever and rash, red eyes, dry or cracked lips or mouth, redness on the palms of the hands and soles of the feet, and swollen glands. Typically, around a quarter of children affected experience cardiac complications, but the condition is rarely fatal if treated appropriately in hospital. It is not known what triggers the condition, but it is thought to be an abnormal immune overreaction to an infection.

Children who presented at hospital with symptoms after February 18 were older on average, with a mean age of 7.5 years old, than the group diagnosed in the previous five years, with a mean age of 3 years old. They also appeared to experience more severe symptoms than past cases, with 60 percent having heart complications, compared with 10 percent of those treated before the pandemic. Half of the children had signs of toxic shock syndrome, whereas none of the children treated before February 2020 had this complication. All patients before and after the pandemic received immunoglobulin treatment, but 80 percent of children during the outbreak required additional treatment with steroids, compared with 16 percent of those in the historical group.

Two of the patients treated after February 18 tested negative for SARS-CoV-2 on an antibody test. The researchers say the test used is not 100 percent accurate, suggesting these could be false negative results. In addition, one of the patients had recently been treated with a high dose of immunoglobulin, a standard treatment for Kawasaki disease, which could have masked any antibodies to the virus.

Taken together, the authors say that their findings represent an association between an outbreak of SARS-CoV-2 virus and an inflammatory condition similar to Kawasaki disease. The researchers say the COVID-related cases should be classified as 'Kawasaki-like disease', as the symptoms were different and more severe in patients treated after March 2020. However, they caution that their report is based on only a small number of cases and larger studies will be required to confirm the association. They also warn that other countries affected by the COVID-19 pandemic might expect to see a similar rise in cases similar to Kawasaki disease.

The syndrome is rare and experts stress that children remain minimally affected by the SARS-CoV-2 infection overall.

“Although this complication remains very rare, our study provides further evidence on how the virus may be affecting children,” said Lucio Verdoni, MD, author of the report from the Hospital Papa Giovanni XXIII in Bergamo, Italy, in a statement. “Parents should follow local medical advice and seek medical attention immediately if their child is unwell. Most children will make a complete recovery if they receive appropriate hospital care.”

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