New findings on children’s syndrome linked to COVID, Kawasaki disease

Today, two studies describe new findings regarding the multisystem inflammatory syndrome associated with COVID-19 in children (MIS-C) and distinct but similar Kawasaki disease (KD).

Low blood pressure, shock, heart dysfunction

In the first study, published in Pediatrics JAMA, a team led by researchers from the U.S. Centers for Disease Control and Prevention (CDC) used laboratory data to compare the geographic and temporal distribution of MIS-C from March 2020 to January 2021 with that of COVID-19 over the same period.

In the largest known cohort of MIS-C patients and their distribution across the United States, the cumulative incidence was 2.1 per 100,000 people aged 21 and under and varied by state from 0.2 at 6.3 per 100,000. The death rate was 1.4%.

Of the 1,733 MIS-C patients, 90.4% had involvement of four or more organ systems, 54% had low blood pressure or shock, 58.2% required intensive care, and 31.0% had abnormal heart function. Pericardial effusion (accumulation of fluid in the sac around the heart) occurred in 23.4%, myocarditis (inflammation of the heart muscle) in 17.3%, and coronary artery dilation or aneurysm (swelling of the heart muscle). a vascular wall) in 16.5%.

Patients aged 18 to 20 had the most severe signs and symptoms of MIS-C, 30.9% with myocarditis, 36.4% with pneumonia and 18.2% with acute respiratory distress syndrome (ARDS). This age group was also the most likely to report ever having had coronavirus-like illness (63%). In contrast, children 0 to 4 years of age had the fewest signs and symptoms of severe MIS-C, but 38.4% had low blood pressure or shock, and 44.3% required intensive care.

Gastrointestinal symptoms, rash, and conjunctival hyperemia (an inflammatory eye condition) occurred in 53% to 67% of MIS-C patients. Other common symptoms included fever, vomiting, rash, and diarrhea. Of all MIS-C patients, 57.6% were boys, 71.3% were Hispanic or black, and the median age was 9 years.

Delayed immune response to coronavirus

The states with the heaviest MIS-C burden were generally in the West and Midwest. The first two peaks in MIS-C nationwide occurred 2-5 weeks after the peaks in COVID-19 and the virus spread from urban to rural areas.

Most cases of MIS-C are thought to occur after asymptomatic or mild COVID-19 infections, with an inordinate inflammatory response coinciding with a spike in antibody production several weeks later, the authors said.

“The geographic and temporal association of MIS-C with the COVID-19 pandemic suggested that MIS-C resulted from delayed immunological responses to infection with SARS-CoV-2,” they wrote. “Clinical manifestations varied by age and by the presence or absence of previous COVID-19.”

Researchers have called for the development of laboratory markers or diagnostic tests to distinguish MIS-C from severe COVID-19 and other inflammatory conditions such as Kawasaki disease. “Doctors need to maintain a high index of suspicion for MIS-C to diagnose and treat these patients quickly,” they concluded.

In a comment for the same journal, Jennifer Blumenthal, MD, and Jeffrey Burns, MD, MPH, both of Boston Children’s Hospital, said the study results show that the absence of prior coronavirus symptoms, particularly in young children, should not reassure pediatricians that MIS-C has not affected their hearts.

“If the entire global pediatric population is at risk of COVID-19 and vaccination will be delayed in the pediatric population compared to adults, this potentially serious finding must remain at the forefront of the differential diagnosis for pediatricians around the world pending further research results, ”they wrote.

Kawasaki disease likely spreads by air

Posted in JAMA network open, the second study was conducted by researchers at Fukuoka Children’s Hospital in Japan to determine the role of droplets in the contact transmission of KD. The longitudinal study involved 1,649 KD patients and 15,586 patients with infectious diseases hospitalized in six centers from 2015 to 2020.

KD is an acute disease that primarily affects children 6 months to 5 years of age – the median age in the KD cohort was 25 months – and is characterized by inflammation of the small and medium blood vessels. Although the cause of KD is unknown, it is believed to occur in genetically predisposed children after exposure to an environmental trigger such as infection.

The researchers found that the number of hospitalizations for KD did not change significantly between April and May in 2015 to 2019 compared to the same months in 2020 (mean, 24.8 vs 18.0 admissions per month; decline of 27.4%; ratio adjusted for the incidence rate [aIRR], 0.73).

Over the same period, however, hospitalizations for droplet and contact respiratory infections fell from an average of 157.6 to 39.0 admissions per month, a decrease of 75.3% (aIRR , 0.25), as were those for gastrointestinal infections (43.8 to 6.0 monthly admissions), a decrease of 86.3% (aIRR, 0.14), for 12,254 fewer infections.

As a result, the KD ratio for droplet- and contact-transmitted respiratory and gastrointestinal infections significantly increased in April and May 2020 (ratio 0.40 vs. 0.12).

“These results suggest that contact or droplet transmission is not a major pathway for the development of Crohn’s disease in Japan and corroborate the findings of previous epidemiological studies indicating that Kermesse’s disease may be associated with airborne illnesses. in most of the cases. Further studies are needed to better understand this intriguing disease, ”the authors wrote.