The first shot at full term is the Hepatitis B vaccine. When there is a cold or other reason why the vaccine cannot be given on time, it can be pushed back by 1-2 days as appropriate, but it is best to be on time to avoid affecting the effectiveness of the vaccine. Hepatitis B vaccine is a special medicine to prevent Hepatitis B. The vaccine can stimulate the body’s ability to prevent Hepatitis B. After vaccination, the human body can stimulate the immune system of the body to produce protective antibodies against hepatitis B virus, so that the human body has immunity against hepatitis B. Once infected again, the human body will quickly produce protective antibodies against hepatitis B virus. Once infection occurs again, the body rapidly secretes antibodies to immediately clear the virus, preventing infection from occurring, protecting the body from harm and achieving the goal of preventing hepatitis B infection. If hepatitis B vaccination is given too late, it may increase the risk of hepatitis B virus infection in infants and young children. In addition, adverse reactions seldom occur after vaccination against hepatitis B. Only a small number of people develop symptoms such as low-grade fever, swelling at the site of vaccination, pain, itchiness, soreness and heaviness in the arms, or symptoms such as fatigue, nausea, loss of appetite, etc., which usually do not require any special treatment, and most of which can be relieved on their own within three days.