After vaccination, babies are prone to general reactions, such as transient fever and transient digestive weakness, which may affect the baby’s mental state and lead to a slight impact on breastfeeding. When the immune system is active, the baby may have a transient discomfort. At this time, the baby does not like to eat milk because it is instinctive to reduce food intake to reduce the burden on the gastrointestinal tract. The general reaction usually disappears gradually in about 3 days, and the baby gradually returns to a normal state.