Platelets of infants may increase after vaccination, which is temporary and small in magnitude, and usually recover gradually in a short period of time, and most of the infants have no obvious abnormality after vaccination. Temporary dysfunction of the immune system after vaccination, related to the relative decline in immunity during vaccine absorption, may lead to changes in blood composition, such as a slight decrease in platelets, accompanied by a decrease in white blood cells. This is a normal physiologic reaction and usually resolves on its own in about two to three days. Parents are advised to strengthen the daily care of their infants after vaccination, monitor the changes in vital signs, and consult the doctor for appropriate treatment if there is a low-grade fever, mild diarrhea, etc. Avoid blindly administering medication, so as not to affect the absorption of the vaccine as well as the health of the infant.