SARS-CoV-2 triggering severe ARDS and secondary HLH in a 3-year-old child with Down syndrome.

Down syndrome (DS) predisposes to severe immunologic reaction secondary to infectious triggers. Here we report a paediatric DS patient with COVID-19 who developed a hyperinflammatory syndrome, severe ARDS and secondary HLH requiring PICU admission and treatment with steroids, IVIG and Remdesivir. Investigations into genetic susceptibilities for COVID-19 and SARS-CoV-2-associated complications warrants systematic clinical and scientific studies.