During the course of COVID-19, neutrophil proportion (PGEE < 0.001), NLR (PGEE < 0.001), and serum levels of CRP (PGEE = 0.024), ESR (PGEE = 0.003), and IL-6 (PGEE = 0.043) were significantly higher in pneumonia patients than pneumonia-free patients, which were quite in contrast to lymphocyte proportion (PGEE < 0.001), T lymphocyte count (PGEE < 0.001), CD4+ T lymphocyte count (PGEE < 0.001), and CD8+ T lymphocyte count (PGEE = 0.001). Here, CD8A is linked to susceptibility to pneumonia measurement.