It is common to hear feedback from parents that their babies develop fever after receiving the leprosy vaccine. This often leaves new parents overwhelmed, anxious and worried, and they may blindly use various pediatric fever-reducing medications. However, parents do not realize that there are many causes of fever and that blind use of medication can only be counterproductive. First, parents should understand the characteristics of fever caused by vaccination. Generally speaking, fever caused by vaccination has characteristics that distinguish it from other types of fever. The ingredients in the vaccine sometimes cause a fever of a transient nature, but the incidence is low, the fever usually does not exceed 38.5°C, and it lasts for a short time. It usually does not cause other diseases and does not require special treatment. An increase in temperature may occur 4-24 hours after inactivated vaccination and can usually last 1-2 days, rarely more than 3 days. Despite the inactivation or attenuation of the causative agent, the leprosy vaccine is still a heterogeneous protein or a substance with antigenic properties, which has a certain irritating effect on the body. Therefore, the leprosy vaccination of babies may cause local or systemic reactions of varying degrees, with fever being the most common reaction. For most babies, low-grade fever is more common and usually does not require special treatment. There are, of course, a few babies who have a more intense reaction, sometimes with a body temperature over 39°C and systemic reactions such as loss of appetite, nausea and vomiting. At this time the baby should rest, pay attention to the hydration, can be used to warm water bath. If necessary, fever-reducing medication should be taken under the guidance of a doctor. Although leprosy vaccination can bring all kinds of adverse reactions, it is also very useful for the baby. This is because as babies grow and develop, they are exposed to a variety of things that inevitably do not carry bacteria. If babies are not vaccinated, they will not have the appropriate antibodies in their bodies and will have no resistance to these germs, thus making them prone to serious consequences. Therefore, parents should not refuse to vaccinate their babies because the vaccine may cause adverse reactions in their babies, as this may pose a threat to their babies’ health, which is not worth the loss.