A person without antibodies is one who is not immune to a certain pathogen and is susceptible to infection as a susceptible person when exposed to a certain pathogen, for example, a person who has not been vaccinated against hepatitis B and does not have surface antibodies to hepatitis B in his body can cause infection with the hepatitis B virus when exposed to a person with hepatitis B. If you do not have antibodies, you can prevent infection by getting vaccinated or by improving your body’s immunity. The purpose of the various vaccinations we receive is to prevent infection by injecting the antigen of a pathogen so that the body produces an immune response and specific antibodies are produced. The current vaccinations against novel coronavirus, including inactivated vaccine, recombinant vaccine, and adenovirus vector vaccine, are all designed to produce protective antibodies against infection with novel coronavirus pneumonia, or the protection rate of the vaccine does not reach 100%, even if one is infected with novel coronavirus, but the disease is generally mild and the chance of severe or critical illness is significantly reduced, which can reduce The rate of death from disease. Therefore, vaccination against novel coronavirus is recommended for people who do not have protective antibodies against novel coronavirus.