The MMR vaccine does not have to be given at eight months, the MMR vaccine is usually given after eighteen months, even if the vaccine is delayed by other factors, it will not have too much effect, but it is not recommended to delay it for too long, so as to avoid affecting the timing of other vaccines. The MMR vaccine is a mandatory vaccine for children, mainly to prevent measles, mumps and rubella, which are respiratory infectious diseases caused by viral infections, and these three diseases may occur throughout the year, with the highest incidence in the spring, which are viral infections caused by respiratory tract transmission. After the MMR vaccine, due to the different constitution, some infants may be irritable due to discomfort, some may also have a low fever, vomiting, loss of appetite and other symptoms, parents do not need to worry too much, this situation will soon be relieved and disappear, if it does not subside after 3 days, or there are signs of aggravation, need to consult a doctor in a timely manner. If some infants are allergic to the components of the vaccine, in order to avoid adverse reactions, they should communicate with their doctors in advance to ensure safe vaccination.