Ask the new crown vaccine: Why Phase III clinical trials are critical to vaccines

some people might think: this question is still 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"?
III. Clinically important because its mission is to prove with rigorous and detailed scientific data whether vaccines are safe and effective. A colloquial saying can more vividly sum up the mission of Phase III. Clinical - "Road far know Miao Li, see Miao heart day by day"!
phase III. Clinical trials such as "Three Ambiguous Fires"
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 (tens of thousands), and two epidemic seasons.
to ensure a lasting test, phase III clinical trials are relatively rigid in their validation time, typically take 2-5 years, and for infectious diseases, at least two epidemic seasons are required.
After the "three real fire" test, many alternative vaccines will fail: the
vaccine human clinical trials have failed more than 200 times, and some respiratory infections of the vaccine has not yet been successful (such as herpes simplex vaccine, respiratory syncytial virus vaccine, etc.).
" new crown vaccine Phase III. Clinical because of the urgency of epidemic prevention and control, it is currently believed that the subjects after full immunization needs to last at least two months, and now the popular end of December, mainly refers to the initial results (such as half of the data) time. 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.if the initial effective validation of preclinical vaccine in Phase III. is a "text play", it is a real "real battle" in Phase III. clinical trials and a key clinical data obtained. 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.
the effectiveness of the vaccine can only be assessed if the phase III clinical observations are mainly observed in the study population. 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 combat", someone will inevitably be infected, in order to prove that someone is not infected because of vaccination, in order to prove the protection of the vaccine.
this is reflected in the end of Phase III. clinical trials. 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. For example, Modelna's plan shows that it needs 30,000 subjects, with the control group ending with 151 people infected with new coronary pneumonia, and AstraZeneta, which ends with 30,000 subjects and 150 infected.
it can be seen that when phase III clinical trials end is not planned, but depends on the control group in Phase III. clinical trials, that is, people who were injected with a placebo without a vaccine, and whether anyone bent on contracting the new coronavirus.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).
may be a 0 and 100% difference between protection and non-protection for one person, but the number accumulated from the population as a whole 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 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 very familiar, that is, after injection will occur redness, fever, etc. , but as long as within a certain acceptable range, these often do not prevent the vaccine approval. Zhu Fengcai said that only serious adverse reactions, vaccine-related specific adverse reactions, after vaccination still occurred serious cases, will affect the fate of the vaccine.
immune pathological response to vaccines requires more people to be vaccinated and follow-up for longer periods of time 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 trouble (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.
" new crown vaccine research and development is still in the first to solve the 'yes or no' stage. 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.