Liu et al. [[7]] and Wan et al. [[8]] have recently reported that total T cell count, CD4 cell count, CD8 cell count were significantly reduced in severely and critically ill patients with COVID-19; no differences were described about CD4/CD8 ratio. In our study we found low CD4 and CD8 count in both the critically ill and the non-critically ill group and, consistently with Wang [[9]], the CD4/CD8 ratio resulted significantly higher in critically ill patients. In conclusion, at admission evaluation of CD4/CD8 ratio could be an additional risk factor and useful parameter for early prediction of progression towards critical illness in COVID-19 hospitalised patients. [Extracted from the article]