Secondary HLH is uncommon in severe COVID-19.

Severe cases of COVID-19, caused by novel coronavirus SARS-CoV-2, have been associated with a hyperinflammatory state.(Huang, Wang et al. 2020) This has been described as a form of secondary haemophagocytic lymphohistiocytosis (sHLH)(Bergsten, Horne et al. 2017) that may contribute to increased mortality.(Ramos-Casals, Brito-Zeron et al. 2014) Screening with the HScore(Fardet, Galicier et al. 2014) to identify cases has been recommended to guide immunosuppressive therapy(Mehta, McAuley et al. 2020).