In a retrospective study of 41 COVID-19 cases conducted by Huang et al. at Zhongnan Hospital of Wuhan University, it was found that severe patients have significantly higher expression levels of proinflammatory factors [IL-2, IL-7, IL-10, granulocyte colony-stimulating factor (G-CSF), interferon-induced protein 10 (IP-10), MCP-1, macrophage inflammatory protein 1 α (MIP-1α)、TNF-α] in their plasma compared to mild parents. Here, IL10 is linked to COVID-19.