The results showed that TNF-α was negatively correlated with SDANN (r = –0.6680, P < 0.0001) and SDNN (r = –0.2767, P = 0.224) and positively correlated with LF/HF (r = 0.4109, P = 0.0005) in COVID-19 patients (Supplementary Figure 3). The gene discussed is TNF; the disease is COVID-19.