Measuring the inflammatory response in viral infections with an eye towards MIS-C

Multisystem Inflammatory Syndrome in Children (MIS-C) caused by a recent SARS CoV2 infection in a child, led to broad screening of acutely ill children for widespread inflammation and systemic disease due to need for early diagnosis and therapeutic intervention. This broad laboratory screening to rule-out MIS-C also inadvertently captured the patients who were found to have seasonal viral upper respiratory infections. Thus, this screening provided a unique opportunity to study the inflammatory response to some of the common viral infections. We performed a retrospective chart review for all patients under 18 who presented to the ER or were admitted to the hospital with a positive test for either 1) Viral URI, 2) Acute COVID-19, or 3) positive SARS CoV2 IgG, suggesting previous COVID-19 infection; between March 2020-October 2022. We reviewed 6628 patient encounters with 5312 encounters meeting inclusion criteria. Here we report that patients who had COVID IgG without other infection identified, most frequently showed widespread inflammation, as indicated by 56.7% of patients with 4 or more positive MIS-C criteria suggesting a diagnosis of MIS-C. One patient had a peak of 15 positive MIS-C criteria. Several seasonal viruses showed multisystem inflammatory responses in limited patients with the most frequent occurring in adenovirus (7.6% >= 4 criteria), and peaks of 9 or 10 criteria in sporadic patients for three seasonal viruses (adenovirus, rhinovirus/enterovirus, and parainfluenza viruses). Acute SARS CoV2 demonstrated elevated inflammatory states similar to seasonal cold viruses with a limited number of patients (4.3%) with >= 4 positive criteria markers of MIS-C, and a peak of 9 criteria. The most significant and largest differences between groups were observed in COVID IgG positive patients in comparison to each of the other viral groups followed by adenovirus compared to 5 out of 6 remaining viral pathogens.