COVID-19 vaccine is a relatively safe vaccine. Under normal circumstances, there is no special harm to the human body. Antibodies can be produced in the body after inoculation, which can help the body to prevent novel coronavirus infection. Generally, three injections are needed in the whole process, but some people will have some side effects after vaccination, such as fever, pain, nausea, vomiting, diarrhea, loss of appetite and so on. However, these symptoms usually relieve themselves in a short time without special treatment. However, a small number of people are allergic. If they are allergic to COVID-19 vaccine, they may have allergic reactions after vaccination, such as itchy skin and poor breathing. If not treated in time, anaphylactic shock may occur. Therefore, people usually need to stay at the inoculation site for half an hour to see if there are any adverse reactions.