Previous studies have suggested that lymphopenia might be related to high levels of IL-10 or IL-6, potentially through a direct role of these cytokines on lymphocytes and/or indirect roles via other cell lineages (e.g., neutrophils and DCs).32–35 Interestingly, we observed elevated levels of IL-6 and IL-10 in the COVID-19 AE group (Supplementary Fig. 5). Here, IL10 is linked to lymphopenia.