PDGFB and COVID-19: However, PDGFB expression was significantly higher among COVID-19 patients in the middle stage compared to those in the early stage who were older than age 40 (FC = 2.17, p = 0.03; Figure 2D) or older than age 50 (FC = 2.15, p = 0.04), but not in the total group of COVID-19 patients in these stages (FC = 0.99, p = 0.61; Table S9 and Figure S9) or among early-stage patients compared to the middle- and late-stage patients combined (p > 0.10; Table S9).