Vaccinations for babies, commonly known as immunizations, are one of the effective measures to protect children from certain infectious diseases. Nowadays, with the promotion of vaccination knowledge, there are probably not many parents who do not know how to get vaccinated on time. However, there are not many parents who do not know what they know, or who know what they know but do not know what they know, or who have some doubts. First of all, the most common concern is that vaccines are made from bacteria, viruses or the toxins they produce. It is true that vaccines are made from pathogenic microorganisms and their metabolites, which are artificially cultured and multiplied so that they lose their ability to cause disease, but they still retain their immunogenicity and have some toxicity. Especially in recent decades, the number of recommended childhood vaccines has skyrocketed, with 11 vaccines and 20 doses typically received by age 2. Therefore, more and more parents are concerned about their infants’ inability to safely cope with these vaccines or suspect that these vaccines may compromise their infants’ immune systems. In response, experts at the Center for Vaccine Education at the Children’s Hospital of Philadelphia have conducted a study on the effects of vaccines on the immune system and the safety of the infant’s immune system in response to multiple immunizations. The vaccine does not weaken the infant’s immune system at all, but rather enhances the infant’s ability to protect against serious diseases. Therefore, you should rest assured that it is safe to give your child immunizations according to the planned immunization program and there is no need to worry. Secondly, is it better to give more or less vaccinations? When it comes to the dosage of vaccines, I should say that it is not right to give more or less vaccines. First of all, if you give too many vaccines, not only will your child not be able to get the disease resistance he or she deserves, but also the immunity may be reduced or even impossible to produce. If we eat more than 500 grams or even kilograms of food in order to get more nutrients, the food we eat will be more than enough, but the nutrients we get will not increase proportionally, instead, it will increase the burden on the stomach and intestines, leading to indigestion and reducing the absorption of nutrients, which is not worth the loss. Secondly, various vaccines are made from germs and viruses and the toxins they produce, and although they have undergone special treatment such as killing and attenuation, they are still toxic to some extent and some reactions may occur after vaccination. In particular, it is impossible to completely remove the substances used for the growth of bacteria or viruses during the production process, and these residual substances may cause allergic reactions, ranging from rashes in mild cases to shock in severe cases. The occurrence of such allergic reactions tends to increase with the number of injections. To avoid accidents, the number of inoculations and the number of injections should be reduced as much as possible without affecting immunity. So, is the fewer vaccinations the better? Neither. As with meals, it is difficult for the body to get enough nutrients without a certain amount. The right thing to do is to follow the planned immunization program, which was developed by scientists through extensive scientific tests and should not be changed at will. For example, babies are given BCG and hepatitis B vaccine at birth, polio vaccine at 2 months, DPT3 vaccine at 3 months, measles vaccine at 8 months, etc. Neither miss or under-vaccinate, nor over-vaccinate. As long as we adhere to such a policy, we can completely avoid some of the side effects of vaccination and reap its benefits, protecting our children from infectious diseases. Furthermore, are the vaccinations effective or not? How to observe the effect of vaccination? We can observe from the following aspects: First of all, we can observe whether there is any change in the area where the vaccination was given after the vaccination. After vaccination, the germs and viruses in the vaccine have to grow and multiply in the body to stimulate the body’s immune system to produce immunity, so certain reactions often occur at the injection site. In the case of BCG vaccine, for example, the skin at the site of the injection is slightly red and swollen for 2 to 3 days after vaccination and disappears quickly, and then becomes red and swollen again locally for about two weeks and breaks down to form an ulcer, usually no more than 0.5 cm in diameter, with a small amount of pus, and then scabs, which leaves a slight scar after the scabs fall off and lasts for about 2 to 3 months. If the above reaction occurs as expected, the vaccination is successful. If no change is seen after the vaccination, it means that the vaccination has failed, and the child should be given a replacement vaccination in time. The next step is to observe whether the child’s resistance to disease has increased. Generally speaking, immunity can be developed two weeks after vaccination, and the immunity level is highest around one month, and then gradually decreases. If, two weeks after vaccination, the child no longer suffers from the kind of infectious disease that can be prevented by the vaccine, especially during the epidemic season or when there is an epidemic of such infectious disease around, it indicates that the vaccination is successful and effective. Finally, how to deal with adverse reactions after vaccination? After vaccination, certain reactions usually occur due to the stimulation of the organism by the vaccine. Some of these reactions are normal, such as local skin changes like redness and swelling after BCG vaccination, but there may also be abnormal reactions due to technical problems or the child’s own deficient immune function. What should be done at this point? Let’s start with BCG vaccination. Clinical data show that the more common complication after BCG vaccination is septic lymphadenitis, with an incidence of about 0.5% to 4%, mostly related to BCG strain, dose, age of the child, route of vaccination and technical level of the vaccinator. If the inflamed lymph nodes are not larger than 1 cm, it is a normal reaction and does not need to be treated. If the swelling is more than 1 cm, and softening occurs and does not subside on its own, local pus extraction can be done under strict sterilization. If local pus has broken out, sprinkle isoniazid powder, then wrap with sterile gauze, and take isoniazid orally at the same time, the dose is calculated as 8~10 mg per kg body weight per day, and the course of treatment is about 1~3 months. Do not use unhygienic methods to squeeze or casually cut open to drain the pus. Plus the DPT3 vaccine. Fever and local reactions often occur after vaccination, with about 2% to 6% of children having a fever of 39°C or more after vaccination, and 5% to 10% having significant local redness, swelling and nodules or pain that lasts for more than 48 hours. Individuals with severe fever may also have convulsions or neurological symptoms (such children should not be re-vaccinated with DPT3 vaccine in the future, but with DPT2 vaccine instead, because neurological reactions are usually caused by the pertussis vaccine), and those with high fever may take antipyretics, while those with convulsions and neurological symptoms should seek prompt medical attention. As for measles vaccination, serious reactions are generally rare, but about 5%-15% of children start to have high fever 6 days after vaccination, which can last for more than 5 days, so it is best to ask a doctor for treatment.