Diarrhea Is a Hallmark of Inflammation in Pediatric COVID-19.

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is a pathogen with enteric tropism. We compared the clinical, biochemical and radiological features of children hospitalized for acute SARS-CoV-2 infection, classified in two groups based on the presence of diarrhea. Logistic regression analyses were used to investigate the variables associated with diarrhea. Overall, 407 children were included in the study (226 males, 55.5%, mean age 3.9 ± 5.0 years), of whom 77 (18.9%) presented with diarrhea, which was mild in most cases. Diarrhea prevalence was higher during the Alpha (23.6%) and Delta waves (21.9%), and in children aged 5-11 y (23.8%). Other gastrointestinal symptoms were most commonly reported in children with diarrhea ( p < 0.05). Children with diarrhea showed an increased systemic inflammatory state (higher C-reactive protein, procalcitonin and ferritin levels, p < 0.005), higher local inflammation as judged by mesenteric fat hyperechogenicity (adjusted Odds Ratio 3.31, 95%CI 1.13-9.70) and a lower chance of previous immunosuppressive state (adjusted Odds Ratio 0.19, 95%CI 0.05-0.70). Diarrhea is a frequent feature of pediatric COVID-19 and is associated with increased systemic inflammation, which is related to the local mesenteric fat inflammatory response, confirming the implication of the gut not only in multisystem inflammatory syndrome but also in the acute phase of the infection.