4-year-old baby fever after the second day of the new crown vaccine, usually for the reaction after the injection of the vaccine, and the baby’s individual differences, common reactions for dizziness, nausea, fever, etc., baby fever can be treated by physical cooling, drug cooling. 1, physical cooling: physical cooling is the baby fever, the more commonly used cooling methods, 4-year-old baby fever after the second day of the new crown vaccine, if the body temperature does not exceed 38 ℃. You can use physical cooling methods, commonly used methods are ice bags cold compresses on the head, warm water baths, so as to play a cooling effect; 2, drug cooling: If the baby’s body temperature exceeds 38.5 ℃, you can use acetaminophen, ibuprofen and other drugs to reduce fever under the guidance of a doctor, can be used with physical cooling, but also need to give the baby more water. If the baby continues to have a fever that does not subside and is accompanied by symptoms such as coughing, coughing and depression, it is often considered to be a respiratory infection caused by viruses, bacteria and other pathogens, and it is recommended to take the baby to the hospital in time to identify the cause and treat it. If your baby has a viral infection, you can take ribavirin, oseltamivir and other medications as prescribed by your doctor. If it is a bacterial infection, you can take cefixime, cefdinir and other medications.