Longer Risk Period for MIS-C in Children With COVID

By Reuters Staff

January 22, 2021

NEW YORK (Reuters Health) - The risk period for development of multisystem inflammatory syndrome in children (MIS-C) with COVID-19 may be longer than currently thought.

More than two million cases of COVID-19 have occurred in children in the United States. As of early December 2020, federal health officials reported 1,288 cases of MIS-C, with a disproportionate majority of cases in Black and Hispanic/Latino children.

When MIS-C related to COVID-19 occurs, its onset has typically been within two to six weeks of illness or exposure. In the Journal of the Pediatric Infectious Diseases Society, clinicians from Walter Reed National Military Medical Center, in Bethesda, Maryland, describe a previously healthy 15-year-old girl who developed MIS-C 16 weeks after first becoming ill with COVID-19.

In their paper, Dr. Blake Cirks and colleagues say the initial constellation of symptoms, and a single febrile episode, in the context of a very high CRP (2.43 mg/dl; normal<0.5 mg/dl) and the long 16-week interval since her prior COVID-19 illness made them doubt a diagnosis of MIS-C on initial presentation.

Published reports show MIS-C presenting within two to six weeks, typically within 21 to 25 days, of COVID-19. The longest documented time span between initial exposure with a positive PCR and MIS-C diagnosis is five weeks in an 8-week-old infant exposed at two weeks of life who developed MIS-C symptoms at seven weeks old, the authors note.

The recent CDC definition for multisystem inflammatory syndrome in adults (MIS-A) requires infection within the preceding 12 weeks. Yet, the longest reported duration between a positive SARS-CoV-2 PCR test and MIS-A diagnosis is 41 days in a 33-year-old male.

Dr. Cirks and colleagues say their case "challenges the assumption" of a two to six week presentation time for MIS-C after acute COVID-19.

"Our case demonstrates a 113-day interval between acute COVID-19 illness and MIS-C diagnosis; future case reports should continue to enumerate this interval so the expected lag period between acute infection and inflammatory syndrome can be better defined," they write.

In their view, two major questions warrant rapid exploration: 1) what is the true lag time between SARS-CoV-2 PCR-positive primary infection and the risk for developing MIS-C?; and 2) could re-exposure to SARS-CoV-2 following prior infection or possibly a different microbial exposure trigger MIS- C?

"We call attention to the period of risk for MIS-C extending up to 16 weeks after a documented SARS-CoV-2 infection," they write. "The mechanisms responsible for MIS-C as well as the risk period warrant future studies and should be a priority for further research."

SOURCE: http://bit.ly/2McyssQ Journal of the Pediatric Infectious Diseases Society, online January 18, 2021.

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