Delaying a vaccine means more risk of exposure to the disease that the vaccine can prevent, and some (mainly Group II vaccines) have a minimum age limit for vaccination, and delaying may result in the child not receiving the vaccine. Vaccine age restrictions Class I vaccines Currently, there are no age restrictions for Class I vaccines (i.e., vaccines that can be given free in the community) except for BCG, but there are some special circumstances for BCG and Hepatitis B vaccines. BCG vaccine: Generally, the vaccine is given at birth in the maternity hospital. Supplementary vaccination requires a visit to a BCG clinic. ＜If the child is <3 months of age, he/she can be directly vaccinated; if he/she is 3 months-3 years of age, he/she has to take a PPD test and the result is negative before he/she can be vaccinated; if he/she is ≥4 years of age, he/she will not be vaccinated. Most children do not need the BCG vaccination, so parents can not worry about it. Hepatitis B vaccine: for the prevention of hepatitis B, the prescribed vaccination time is one dose at birth, one month and three doses at 6 months of age, and there is no time limit for the latest vaccination; however, if the mother is hepatitis B surface antigen positive, it is not recommended to postpone the hepatitis B vaccination, so parents in this situation should contact the local vaccination agency as soon as possible to arrange the vaccination in advance. Other vaccines such as polio vaccine, diphtheria vaccine, influenza vaccine, MMR vaccine, cerebral B vaccine, varicella vaccine, and hepatitis A vaccine do not have a latest vaccination time limit. Some vaccines have restrictions on the latest age of vaccination, and regulations vary from region to region, so parents should contact their local vaccination agency as soon as possible. Pentavalent vaccine: Replaces diphtheria and polio vaccines and prevents Haemophilus influenzae type B (Hib) infection, and allows children to receive fewer doses of vaccination. Hib vaccine: Prevents Hib infection and is given at the latest at the age of 5 years. Quadruple vaccine: Prevents Hib + Hib infection and is given no later than 24 months of age. 13-valent pneumococcal conjugate vaccine: to prevent Streptococcus pneumoniae infection, the time limit for vaccination varies from place to place. Generally speaking, if full vaccination is needed, the first dose should be given no later than 4 months of age, the third dose should be completed within 6 months of age, and the booster should be given no later than 15 months of age. Rotavirus vaccine: To prevent rotavirus diarrhea, the first dose of imported rotavirus vaccine should be given no later than 12 weeks of age, with an interval of no more than 10 weeks between doses; and the third dose no later than 32 weeks of age; domestic rotavirus vaccine should be given no later than 3 years of age. Hand, foot, and mouth disease vaccine: Prevention of hand, foot, and mouth disease caused by EV71, vaccination at the latest 5 years of age. There are also some post-exposure vaccinations, such as rabies vaccine and tetanus vaccine, that are not recommended to be postponed. During an epidemic, it is still best for moms and dads to check if the vaccination clinics are open as usual, with or without delays, etc. before the scheduled vaccination time, and try to get the vaccination on time. Rather than letting your child run around naked without vaccination, early communication and early vaccination and prevention is the best way to handle the situation. If vaccination is delayed, it is also important to make up the vaccination in time when it is convenient. What are the precautions to take when going for vaccination? 1. It is recommended to make an appointment for consultation by phone or internet before going for vaccination to avoid gathering at the vaccination clinic. Generally speaking, consultation channels can be found in the public WeChat numbers of local CDC and community health service centers. 2. Pay attention to the channel dedicated to the vaccination clinic, and try not to cross the route with the attending crowd. According to the relevant norms in China, vaccination clinics are generally far away from fever clinics and other areas, and have special access, which is relatively safe compared to other parts of the hospital. When you go for vaccination, avoid taking public transport; 4. Look after your child well outside, besides wearing a mask and other means to protect your respiratory tract, hand hygiene is also crucial, watch your child not to touch, and don't let your child eat your hands, rub your eyes with your hands, pick your nose, etc. 5. You can carry disinfectant wipes or hand sanitizer to clean your child's hands at any time, or put gloves on your child. What are the precautions after inoculation? 1. After vaccination, observe for 30 minutes before leaving the vaccination clinic. During the observation period, if the vaccination clinic is crowded, you can observe in the outdoor area near the clinic, which is relatively open and less crowded, but pay attention to stay away from the visiting crowd. 2. Some children may have fever, local redness and swelling and other uncomfortable symptoms after vaccination, which can generally be relieved without special treatment. 3. At present, many local hospitals have opened network or telephone consultation, so if children have uncomfortable symptoms after vaccination, it is recommended to give priority to network or telephone consultation and then go to the hospital if they cannot handle it.