According to the existing facts, COVID-19 is prone to infection for a long time, and attacks the immune system, and the immunity of the population continues to decline. Decreased immunity has a limit (immune deficiency), which can cause opportunistic infections, tumors and other problems. In addition, myocarditis and neurological problems should not be ignored. In this paper, we guess that the virus invasion of cells is the result of the interaction of proteins on the membrane. Epidemiology predicts that the symptoms related to COVID-19 are follow by a biased normal distribution, which is at the bottom, and further outbreaks will occur in the future. We also mentioned measures that should be taken now (Promote detection of immunity, such as CD4 cell counts).