The vaccine itself is a reduced-activity or inactivated virus, and a side effect of fever may occur after vaccination; fever is usually normal within 1-2 days. Some adverse reactions may occur after vaccination, including local and systemic adverse reactions. For example, redness, swelling and pain at the injection site are localized adverse reactions, and fever is a systemic adverse reaction. If the fever is low, there is no need to worry too much, usually 1-2 days after the body temperature will gradually drop to normal. You can drink plenty of boiled water or lower the temperature physically. If the fever is above 38.5℃, recurrent high fever, accompanied by other obvious discomfort, etc., you need to consult the hospital for blood test to determine the situation and appropriate treatment. After vaccination, you should rest appropriately and do not do strenuous exercise, which is conducive to the production of antibodies in the body.