Two studies today describe new findings of the COVID-19-associated multisystem inflammatory syndrome in children (MIS-C) and the obvious but similar Kawasaki disease (KD).
Low blood pressure, shock, heart function
In the first study, published in JAMA Pediatricsa team led by researchers from the US Centers for Disease Control and Prevention (CDC) used laboratory data to compare 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 group of MIS-C patients and their distribution in the United States, the cumulative incidence was 2.1 per 100,000 people 21 and younger, ranging from 0.2 to 6.3 per 100,000. mortality rate was 1.4%.
Of the 1,733 MIS-C patients, 90.4% had at least four organ systems, 54% had low blood pressure or shock, 58.2% required intensive care, and 31.0% had abnormal heart function. Pericardial effusion (fluid buildup 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 (ballooning of a vessel wall) in 16.5%.
Patients aged 18 to 20 years had the worst MIS-C signs and symptoms, with 30.9% with myocarditis, 36.4% with pneumonia and 18.2% with acute respiratory distress syndrome (ARDS). This age group would probably also report that they had a previous coronavirus-like disease (63%). In contrast, children aged 0 to 4 years had the least severe MIS-C signs and symptoms, 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 include fever, vomiting, rash and diarrhea. Among 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
States with the heaviest burden of MIS-C were usually in the West and the Middle East. The first two rural points of MIS-C occurred 2 to 5 weeks after COVID-19 spikes and viral spread from urban to rural areas.
Most cases of MIS-C are thought to occur after asymptomatic or mild COVID-19 infections, with an unusual inflammatory response that coincided with peak antibody production a few weeks later, the authors said.
“The geographic and temporal association between MIS-C and the COVID-19 pandemic suggested that MIS-C was the result of delayed immunological responses to SARS-CoV-2 infection,” they write. “The clinical manifestations varied according to age and the presence or absence of the preceding COVID-19.”
The researchers requested that laboratory markers or diagnostic tests be developed to distinguish MIS-C from severe COVID-19 and other inflammatory conditions such as Kawasaki disease. “Physicians should maintain a high suspicion for MIS-C to immediately diagnose and treat these patients,” they concluded.
In a commentary in the same journal, Jennifer Blumenthal, MD, and Jeffrey Burns, MD, MPH, both of Boston Children’s Hospital, said the study’s findings show that the lack of previous coronavirus symptoms, especially in younger children , should not rest assured. pediatricians that MIS-C did not affect their hearts.
‘If the entire pediatric population of the entire world is at risk for COVID-19 and vaccination in the pediatric population is delayed compared to adults, this potentially serious outcome should remain at the forefront of differential diagnosis for pediatricians around the world in anticipation of further outcome. research, ‘they wrote.
Kawasaki disease probably spread in the air
Published in JAMA Network open, the second study was led by researchers from Fukuoka Children’s Hospital in Japan to determine the role of droplet versus contact transfer of KD. The longitudinal study from 2015 to 2020 involved 1649 patients with KD and 15 586 patients with infectious diseases hospitalized in six centers.
KD is an acute disease that usually affects children from 6 months to 5 years of age – the average age in the KD cohort was 25 months – and includes inflammation of small and medium blood vessels. Although the cause of KD is unknown, it occurs in children with a genetic predisposition after exposure to an environmental condition such as an infection.
The researchers found that the number of hospitalizations for KD between April and May in 2015 to 2019 did not change significantly compared to the same months in 2020 (average 24.8 versus 18.0 admissions per month; 27.4% decrease; adjusted incidence rate relationship [aIRR], 0.73).
Over the same period, however, hospitalizations for droplet or contact-borne respiratory tract infections dropped from an average of 157.6 to 39.0 admissions per month, a decrease of 75.3% (aIRR, 0.25), similar to those for gastrointestinal infections. (43.8 to 6.0 (monthly surveys), a decrease of 86.3% (aIRR, 0.14), for 12,254 fewer infections.
As a result, the ratio of KD to droplet or contact-transmitted airway infections and gastrointestinal infections increased significantly in April and May 2020 (ratio 0.40 vs 0.12).
“These findings suggest that contact or droplet transmission is not an important route for KD development in Japan, and it supports the findings of previous epidemiological studies suggesting that KD may in most cases be associated with diseases in the “More extensive studies are needed to further understand this intriguing disease,” the authors wrote.