CSF2 and COVID-19: Nevertheless, our surprising findings fully supported the emerging notion that GM-CSF might be a key biomarker for SARS-CoV-2-induced cytokine storm in a subset of COVID-19 patients with more severe pneumonia often escalating to respiratory failure and death (Hue et al. 2020; Gibellini et al. 2020; Blot et al. 2020; Thwaites et al. 2021; Zhao et al. 2021).