Encouragingly, the top‐ranked differentiators identified by the machine‐learning algorithm were also among the most differentially expressed proteins, like C9 (logFC(MPX‐Control) = 1.4 ± 0.2) and TTR (logFC(MPX‐Control) = −1.2 ± 0.1) for differentiating MPX cases and healthy individuals, or CHFR1 (logFC(MPX‐COVID‐19) = −1.2 ± 0.3) or LCP1 (logFC(MPX‐COVID‐19) = 0.6 ± 0.1) for differentiating MPX from COVID‐19, respectively (Fig 2F). This evidence concerns the gene C9 and COVID-19.