In this prospective study, using the Simoa technology, we confirmed that type I IFN response was elevated in patients with severe and critical COVID-19 pneumonia, compared with healthy controls (14–17, 19, 20, 29) correlated with plasma viral load, and associated with a decrease in pDC in blood, perhaps due to migration of these cells into the lung, the active site of the viral infection, as demonstrated for HIV infection (30, 31). This evidence concerns the gene PDC and HIV infectious disease.