Currently, it is believed that blood test indexes such as blood routine have high clinical value for patients with COVID-19.15 The increase in CRP and the decrease in LY are closely related to the severity of COVID-19.6,16-18 The results of this study showed that LY was lower while CRP level was higher in the common infection group than those in the asymptomatic infection group and the mild infection group, which is in line with the previous results. This evidence concerns the gene CRP and infection.