Why phase III clinical trials of the new crown vaccine are critical

why are Phase III. clinical trials critical to the new crown vaccine?Maybe someone will think: This question still needs to be asked?! Important for all vaccines, as only Phase III.But listing is not the goal, to provide safe and effective protection for mankind is. "If you know a person for a few days, can you believe you had a life-long relationship with him?" Recently, Zhu Fengcai, deputy director of the Jiangsu Provincial Center for Disease Control and Prevention, accepted an exclusive interview with a reporter from Science and Technology Daily, he made an image of the example, the vaccine is the same, only soon after the development, do not take the "three ignorant real fire", how to refine out, so as to "protect you from the book"?Phase III. Clinically important because its mission is to prove with rigorous and detailed scientific data whether the vaccine is safe and effective. A colloquialism can more vividly sum up the mission of Phase III. Clinical - "Luyao know Miao Li, see Miao heart day by day"!Phase III. Phase III clinical trials, such as the "three-ambiguous fire"III. Phase III. Phase III clinical trials are mainly to evaluate the protective effectiveity of vaccines. Its "three real fires" test vaccines with real endemic areas, large sample sizes (thousands), and two epidemic seasons.In order to guarantee a lasting test, phase III clinical trial validation time is relatively rigid, generally takes 2-5 years, for infectious diseases, need to go through at least two epidemic seasons.After the "three real fire" test, many alternative vaccines will fail: AIDS vaccine human clinical trials have failed more than 200 times, and some respiratory infectious diseases vaccine has not yet been successful (such as herpes simplex vaccine, respiratory syncytial virus vaccine, etc.).“ The phase III clinical phase of the new crown vaccine, due to the urgency of epidemic prevention and control, currently believes that the subjects need to be fully immunized for at least two months, and now the end of December, the end of the epidemic, mainly refers to the time to obtain preliminary results (such as half of the data). Zhu Fengcai said that only in this way, the vaccine itself, the interaction between the vaccine and the human body, clinical research methods, such as the choice of these possible leaks, it is possible to be found, and then constantly corrected to avoid a large number of use on the market accident.The effective premise of Phase III clinical trials is that "human infection"If the initial effective validation of Phase III. Preclinical Vaccines is a "text play", then in Phase III. Clinical trials is a real "real battle" and access to key clinical data. Why did you say it was a "cultural play"? For example, in the preliminary validity verification of Phase II. Clinical trials, the effectiveness is indirectly demonstrated by detecting the concentration of the antibody. In preclinical trials, animal trials are used to demonstrate the possible protective power of the vaccine.“ Phase III. The main clinical observations included the incidence of the disease in the study population before the effectiveness of the vaccine can be assessed. Zhu Fengcai explained, "Only by comparing the cases of new coronary pneumonia in the vaccinated and unvaccinated populations can the protection effectiveness of the new crown vaccine be assessed." "real "real battle", someone is bound to be infected, in order to prove that someone is not infected because of vaccination, in order to prove the protection of the vaccine.The end of Phase III clinical trials reflects this. Internationally, it is believed that 14 days after the full vaccination of the new crown vaccine, it is necessary for the control group to have new coronary pneumonia due to infection with the new coronavirus in order to reach the end of the test, and the specific number of people infected is required. Modelna, for example, said it needed 30,000 subjects, with 151 in the control group ending up with new coronary pneumonia, and AstraZenecom at 30,000 and 150 infected.It can be seen that when phase III clinical trials end is not planned, but depends on the phase III clinical trial control group, that is, people who were injected with a placebo but not vaccinated, whether anyone has been infected with the new coronavirus.These answers, only Phase III. Clinical can give!What is the protective effect of the vaccine? This is the answer that only Phase III. Clinical can give. For most viral vaccines, protection is required to be more than 75 per cent effective. For the new crown vaccine, World Health Organization (WHO) guidelines state that in randomized controlled trials, the vaccine must be at least 50 per cent effective (at least 30 per cent of the lower credible range). Perhaps for one person, protection and non-protection are 0 and 100% different, but the number accumulated from the overall population is related to the probability that each person will receive protection. The amount and proportion of meso-antibodies produced in Phase II clinical trials is only circumstantial evidence and does not answer whether the antibody has the ability to protect the body from viruses. There are also questions that require long-term observation to be answered. For example, what is the acute toxicity response of the vaccine? What is the immunopathological response of the vaccine? “ The former is familiar to all, that is, redness, fever, etc. that occur after injection, but as long as it is within a certain acceptable range, these often do not prevent the vaccine from being approved. Zhu Fengcai said that only serious adverse reactions, vaccine-related specific adverse reactions, vaccination after the still serious cases, etc. , will affect the fate of the vaccine. The immune pathological response of the vaccine needs to be inoculated to the population and follow-up observation for longer to appear, because the body's immune response is a very complex process in the body. Zhu Fengcai gave a very image of the example, to help understand the immune pathological response - "for example, a unit has a strong ability to work a number of elite soldiers (the functional components of the vaccine immunogenicity is very good), but do nothing to stand and see even a lot of (other than functional components of protein), you can hardly guarantee that these people will not come to trouble for a long time." Zhu Fengcai said that the composition of vaccine products is more complex, in history, even if approved clinical, there are problems due to safety and de-market situation. “ The development of the new crown vaccine is still in the first phase of solving the 'yes or no'. Its true protection, it will inevitably require a large population of Phase III clinical trials, a long time 'test', people can get scientific and objective answers. Zhu Fengcai said, therefore, the new crown vaccine research and development will continue for a long time. (Science and Technology Daily)