Recently, we have encountered a series of cases of aggravation, recurrence or aggravation of vaccination reactions due to parents being too anxious to administer preventive vaccination when their children have not yet recovered from diarrhea or respiratory infections. The following talks about how to choose vaccination and timing for your child. Healthy children can undoubtedly be vaccinated in accordance with the nationally prescribed procedures. For other voluntarily selected vaccines such as rotavirus, influenza virus, streptococcus pneumoniae vaccine, etc. Parents should choose according to the child’s physique and environment at their discretion, and children with allergies should be more cautious. Here are some points to note: 1, do not think that as long as there is a vaccine, vaccination, various viruses, bacteria often have a variety of types, and constantly mutating, the success rate of vaccination to produce antibodies is not 100%, including China’s hepatitis B vaccine, even after the required three vaccinations, there are about 10% of children do not have antibodies produced. 2. Vaccination was once considered the most successful method for human beings to control infectious diseases, but in recent years it has been gradually recognized that multiple vaccinations are one of the reasons for the increased incidence of allergic diseases in children. 3. After certain vaccinations, there are often transient reactions, such as fever, diarrhea, cold, and changes in white blood cells and C-reactive protein in blood routine. Therefore, in the short term after vaccination, due to pay attention to proper diet and increase in clothes, you should take the initiative to explain clearly to the doctor during the visit, otherwise it is easy to over-treat. For children who have not fully recovered from recent coughs and diarrhea, do not rush to get vaccinations, specifically weighing the pros and cons and weighing the necessity and safety of current vaccinations. Especially for non-scheduled vaccines one should not be in a hurry to get vaccinated. In short, we should have the understanding that preventive vaccinations have both advantages and disadvantages, they can prevent and cure diseases, but they can also cause diseases, allergies, and even bring more serious consequences. It is important to apply them with evidence, weighing the pros and cons, and choosing the right time.