MMR is a collective term for three different diseases: measles, rubella and mumps. The MMR vaccine is a combination vaccine that prevents the development of acute respiratory infections such as measles, mumps and rubella. Fever occurs when the vaccine triggers the body’s immune system, which is a more common manifestation after vaccination. As an antigen, the MMR vaccine enters the body and stimulates an inflammatory response, which may result in fever after vaccination. If a low temperature occurs after MMR vaccination, the fever can usually subside on its own by drinking plenty of fluids, paying attention to rest, and eating a light diet. However, if the temperature exceeds 38.5℃, or if the fever persists without relief, you should go to the hospital promptly.