The mechanism of vaccine is different from that of therapeutic drugs. After entering the body, the antigen in the vaccine is not directly metabolized, but is presented by the immune system. After recognition by immune cells, antibodies are produced, and then play a role in preventing virus infection. "Mom, the injection place still hurts today", "I'm so sleepy and have to sleep again"... Recently, many children aged 3 to 11 have been vaccinated with the new crown vaccine. Their little "complaints" make parents feel very worried. It is said that these phenomena are normal reactions to the new crown vaccine, but some parents still mutter: is this related to the dose of the child's vaccine? Why is the vaccine dose the same for children and adults? What kind of reaction is normal? In response to the above problems, the reporter of science and technology daily interviewed Zhang Yuntao, chief scientist of Sinopharm China, on November 20 to answer your questions. Most vaccine doses are "equal" Children's dosage after illness is generally less than that of adults, but in the vaccination of Xinguan vaccine, the vaccination dose of children aged 3 to 11 is the same as that of adults, but small children carry the same dose of vaccine as adults. Will their bodies be overwhelmed? The dosage of therapeutic drugs should consider the weight of the drug user, and may also consider the surface area of the drug user's body. "The mechanism of the vaccine is different from that of therapeutic drugs. After entering the body, the antigen in the vaccine is not directly metabolized, but is presented by the immune system. After recognition by immune cells, antibodies are produced, and the antibodies play a role in preventing virus infection." Zhang Yuntao said that the process of producing antibodies by the vaccine has no correlation with body surface area and body weight. In fact, the vast majority of vaccine doses do not distinguish between adults and children. For example, hepatitis B vaccine, cervical cancer vaccine, pneumonia vaccine did not set different doses for different groups. "For example, infants will also be injected with IPV vaccine (inactivated poliomyelitis vaccine), and the injection amount of young children is the same as that of adults." Zhang Yuntao said that generally speaking, under the premise of ensuring safety, it is a common method in the world to adopt a unified dose of vaccine. In the process of clinical research, the developers of new crown vaccine conducted grouping tests of high, medium and low doses for adults and children. It was found that the immune effects of adults and children were basically the same at the same dose. "At present, the public is vaccinated with medium dose Xinguan vaccine rather than high dose, because the medium dose is enough to stimulate effective immune protection." Zhang Yuntao concluded that the principle of vaccine dose determination is to select the dose that can play the most preventive role as far as possible under the principle of ensuring safety. The immune effect of children after vaccination can be close to "full grid" Some parents worry that the child's immune system is still developing. Can vaccination play its due role at this time? "First of all, in terms of mechanism, after the vaccine enters the children's body, the mechanism of antibody production is exactly the same as that of adults. There is no difference." Zhang Yuntao explained. Secondly, although the children's immune system is still developing, in fact, the immune system of children over 3 years old has been basically perfect and close to that of adults. So, after the child is vaccinated, can the immune effect reach the "full grid"? The answer is, close to the full grid. Data show that immunogenicity refers to the performance that can cause immune response, that is, antigens can stimulate specific immune cells, activate, proliferate and differentiate immune cells, and finally produce immune effector antibodies and sensitized lymphocytes. "From the research data of Xinguan vaccine, the immunogenicity of people aged 18 to 59 is the best, followed by those aged under 18, and those aged over 60 is the worst." Zhang Yuntao explained that this is because the immunogenicity of the elderly decreases with the degradation of various functions as the human body ages, The immunogenicity of people under 18 years old is better than that of the elderly. "But in fact, this difference is very small, not particularly obvious and not statistically significant. Therefore, the vaccination strategies of all ages are the same," Zhang Yuntao added. The research on new crown vaccine for children is carried out simultaneously with that for adults Although the vaccination of the new crown vaccine for people aged 3 to 11 has only been started recently, the research work related to the injection of the new crown vaccine for children is carried out simultaneously with adults. It is reported that on the day when the clinical trial of Sinopharm China Biological New Crown vaccine was launched (April 12, 2020), the research on two and three doses of new crown vaccine in the age group of 3 to 17 years was carried out. In addition, Sinopharm China biology has also launched a systematic study on the safety and immunogenicity of new crown vaccine for people aged 3 to 17 in the UAE. "There is a strict approval process for the approval of the use of the new crown vaccine in each age group, and there needs to be sufficient corresponding data for emergency use or marketing approval." Zhang Yuntao said that therefore, it is necessary to consider in advance in the design of clinical trials, so as to better serve the formation of the national immune barrier. When conducting comprehensive research and judgment on the emergency use of Xinguan vaccine between the ages of 3 and 17, the data required include neutralizing antibody data, safety data, etc. "Safety data include systemic safety data and local safety data. For example, local pain, redness, drowsiness and rare adverse reactions should be observed." Zhang Yuntao said that in terms of the incidence of adverse reactions of Xinguan vaccine, the research results show that adults and children are the same, and there is no difference. Extended reading Children should pay attention to these when vaccinating "If nothing happens half an hour after vaccination, there should be no serious adverse reactions." Zhang Yuntao said that Xinguan vaccination for people aged 3 to 11 has been carried out for some time, and the vaccinated children mainly have three adverse reactions: fever, local pain and sleepiness. In fact, with the significant improvement of vaccine production process, the R & D process of new crown vaccine in China is generally at an advanced level. "The safety data of children vaccinated with Xinguan vaccine should be better than that of other vaccines." Zhang Yuntao said that the vaccine process has been very mature after years of development, and advanced automatic control technology has been integrated and applied. For example, the bioreactor used in the new crown inactivated vaccine uses more advanced control technology and more optimized inactivation process; In the purification step after inactivation reaction, the new crown inactivated vaccine may have less impurities due to the use of more advanced purification technology and materials. All these provide an important guarantee for the safety of the vaccine. So, what should children pay more attention to than adults? At the press conference previously held by the joint prevention and control mechanism of the State Council, immunization planning experts said that they should not only understand the process of Xinguan vaccination, but also pay attention to the health status of their children. Do a good job in counseling, because children over the age of 5 may have some psychogenic reactions. Older children should avoid strenuous exercise and stay for 30 minutes. In case of any suspected adverse reaction in vaccinated children, it shall be reported in time. In case of overlap with other immunization planning vaccines or non immunization planning vaccines, be sure to ensure that the interval between the new crown vaccine and other vaccines is more than 14 days. (outlook new era)