Some vaccines may now require one dose, and a few require two or three doses. Generally live attenuated vaccines require only one dose, while inactivated vaccines usually require multiple doses. Live attenuated vaccines proliferate in the body after vaccination, inducing immunity and providing strong protection, and good immunity can be achieved after a single vaccination. However, some live attenuated vaccines retain a certain degree of virulence and may induce related diseases if there is an immune deficiency. Inactivated vaccines usually require multiple doses, and because the virus is inactivated, they are safer but have a shorter duration of immunity, and the immune effect of a single dose is usually lower than that of attenuated vaccines, but the difference in preventive effect after multiple doses is usually small. There is also a difference between one, two, and three doses of Neocoronavirus vaccine required to prevent Neocoronavirus. The one-dose vaccine is recombinant neocoronavirus vaccine (adenovirus vector type 5), and the two-dose vaccine is inactivated neocoronavirus vaccine. The difference between the two is that the immunization mechanism of the vaccine is different, so there is a difference in the number of doses required, but the protective effect is approximately the same, so there is no need to worry too much about the difference between one and two doses. Prevention is the most important part of disease treatment, and the main purpose of multiple vaccinations is to strengthen the effect of the vaccine. Therefore, patients need to choose the type of vaccination according to their situation. Some patients who receive two doses of vaccine need to complete the vaccination on time in order to have a good preventive effect on the disease.