It is possible that babies may still have a reaction to the second dose of MMR vaccine, but there are individual differences. Each baby’s body is different, and the body reaction after receiving MMR vaccine is also different. Some babies will have reactions such as swollen lymph nodes in the neck or face, slight fever, rash, etc., which may also occur in the second vaccination; some babies have no reaction in the first vaccination, but may have a reaction in the second vaccination. However, in general, the safety of MMR vaccine is relatively high, and most babies will not have a strong reaction when they receive the second injection. However, babies who are allergic or hypersensitive to the vaccine should pay attention and consult a medical professional before vaccination. In addition, babies should not receive the vaccine when they are suffering from an acute illness, have a fever, or are having an acute attack of a chronic disease. After vaccination, if there is a serious adverse reaction, consult a doctor in time.