Normal people can eat some room-temperature watermelon in moderation after vaccination, but it is not recommended for people with diseases that limit high sugar intake, such as diabetes. Eating room-temperature watermelon will not negatively affect the body or the effectiveness of the vaccine, but you should avoid eating watermelon that has been frozen for a long time. Because refrigerated watermelon may cause digestive symptoms such as nausea, vomiting, bloating, abdominal pain, diarrhea, etc. It may also cause diarrhea due to bacterial infection, etc. caused by prolonged refrigeration, which can be easily confused with adverse digestive reactions caused by vaccines at this time and can adversely affect the subsequent selection of treatment measures and easily delay the disease. In addition, it is not recommended to eat watermelon after vaccination if there are adverse GI reactions, such as nausea, abdominal discomfort, diarrhea, etc. Both room temperature and frozen watermelon may aggravate the adverse GI reactions. In addition to not eating watermelon, it is also not recommended to consume other fruits. It is recommended to eat a light and easily digestible liquid or semi-liquid diet, and avoid eating cold and greasy foods. Spicy and stimulating foods are not recommended after vaccination, regardless of whether there are adverse reactions or not, as they are prone to gastrointestinal symptoms and local adverse reactions. It is also not recommended to eat hairy foods, such as seafood, beef and mutton, eggs, etc., to avoid inducing allergic reactions.