New Research on Kawasaki Disease and Covid-19: What You Need to Know

Earlier this week, new research was published on children who presented to hospital suffering symptoms similar to Kawasaki disease. The rare condition, identified in Japan in the 1960s, is characterised by fever, rash and swelling of the blood vessels that can cause the distinctive symptoms of bloodshot eyes and a red tongue. Kawasaki disease has long been thought to be triggered by an immune system hyper-response to infection, but the search for a specific pathogenic trigger has been unsuccessful.

Now new case reports suggest a similar condition has emerged during the Covid-19 pandemic. The condition, dubbed Paediatric Inflammatory Multisystem Syndrome Temporally associated with SARS-CoV-2 (PIMS‑TS), has features that overlap with both Kawasaki disease and toxic shock syndrome. It is also known as Multisystem Inflammatory Syndrome in Children (MIS-C).

Strawberry tongue is a characteristic symptom of Kawasaki disease. Image From Healthline.

The study published by the Journal of the American Medical Association (JAMA) reported the cases of 58 children who presented with symptoms matching diagnostic criteria for PIMS-TS. Abdominal pain and rash were the most common symptoms, affecting over half of patients. Symptoms matched criteria for Kawasaki disease in 22% of patients.

In other respects, PIMS-TS differs from Kawasaki disease. Kawasaki patients are typically 2 to 3 years old and no older than 5, whereas the median age of PIMS-TS patients in the JAMA study was 9 years.

Most notably, three quarters of patients had evidence of current or prior Covid-19 infection or exposure. The finding matched that of Birmingham University-based researchers. Their pre-print released on 7 June (not yet peer reviewed) showed the immune profile of PIMS-TS patients was “similar to that observed in samples from hospitalised adult Covid-19 patients,” even though other markers showed the virus had already been controlled.

These new studies update reports from mid-May of a “Kawasaki-like disease” from doctors in Bergamo, Italy, a Covid-19 hot-spot. The researchers reported in The Lancet a 30-fold increased incidence in Kawasaki disease in comparison with the five years prior to the beginning of the Covid-19 pandemic.

As in the British studies, Italian researchers reported an increased median age of patients, up from 3 years old before the pandemic to 7.5 years old now. They estimated that the condition affected 1 in every 1,000 children exposed to SARS-CoV-2.

The mortality rate of PIMS-TS is low, similar to Kawasaki disease at less than 1%. However, medical attention is essential in order to reduce the risk of arterial swelling in the coronary arteries. Japanese research shows that Kawasaki patients who suffer aneurysms are known to have increased mortality for the rest of their lives. On the up-side, those who survive without heart problems tend to live longer, healthier lives.