There are usually no sequelae after the third injection of the new crown. Sequelae refer to some kind of tissue or organ defect or dysfunction that remains after the body’s condition has basically improved on the basis of the disease. However, some adverse reactions may occur after the third injection, including local adverse reactions and systemic adverse reactions. 1. Local reactions: a few people may experience slight pain, itching, redness, swelling, hardness and other adverse reactions at the localized inoculation site after the third injection of the new crown, it is recommended to avoid rubbing the localized area on the same day and not to do strenuous activities, so as not to aggravate the adverse reactions. 2. Systemic reactions: a very small number of people may experience dizziness, headache, low fever, fatigue, muscle pain, loss of appetite, nausea, vomiting, diarrhea and other systemic adverse reactions after vaccination. It is recommended that if localized adverse reactions occur, rest and observe at home first. If the symptoms are not relieved or have a tendency to worsen, or if severe allergic reactions occur, go to the hospital for consultation in time.