The fact that the epidemic is still so serious even after the vaccine has come out is generally due to incomplete coverage by the vaccine, limited effectiveness of the vaccine in preventing infectious diseases, and the stronger ability of infectious diseases to spread during the epidemic, and so on. 1. Vaccine does not completely cover: a part of the population is not vaccinated and not actively vaccinated, this part of the population is easily infected by the viruses of certain infectious diseases. 2. The effect of vaccines in preventing infectious diseases is limited: vaccinated people may be infected, and not everyone who has been vaccinated is absolutely free from infections, because everyone’s physical condition and sensitivity to drugs are different. 3. Infectious diseases are highly transmissible: for example, the New Coronavirus is highly transmissible and spreads through airborne transmission as well as through contact. In order to fight against infectious diseases, everyone should comply with the law on the prevention and control of infectious diseases, and take the initiative to report and quarantine any unintentional contact with infectious disease patients and prevent the spread of infectious diseases, so as not to be negligent and careless, so as not to jeopardize their own health and the health of others.