The MMR vaccine is a preventive shot to be given under the national immunization program. 90% of children will not develop a fever, and some will have a fever. Fevers tend to develop within 24 hours of vaccination, usually a low fever of about 38°C for 1-2 days, or at most two days, and not for very long. If a high fever does appear or if the fever lasts for more than three days, it is possible that the disease is unknown to the patient and is triggered by the vaccination. If the fever exceeds 38.5°C, it is also important to see if the vaccine is reflected in this child very significantly and the high fever requires medical intervention and guidance.