After vaccination, the fever is usually mild and disappears in 2-3 days, but the exact time depends on the individual’s body type and whether he/she takes good care of the vaccine. Most people do not have fever after vaccination, but a few may have fever, which is related to the individual’s constitution. Fever (usually low fever), rash, local redness and swelling after vaccination are mostly reactions of the body caused by normal immune response, which can recover on their own within 2-3 days, and those with strong resistance may recover on the day of fever, so there is no need to be overly nervous. However, if improper care is taken during this period, such as contact with water at the vaccination site, inadequate local hygiene and cleaning, or excessive exercise, it may cause infection at the vaccination site, resulting in prolonged fever, and timely consultation with the fever clinic or the corresponding department is required. If fever occurs after vaccination, physical cooling can be used, such as wiping with a warm towel on the neck, armpit, or groin area, which can effectively lower the temperature, and avoiding the vaccination site when wiping. If physical cooling is ineffective and the fever does not improve after 3 days, seek medical attention.