Chen Wei's team's new crown vaccine phase II clinical trial results: can induce immune response

　　Results of the second phase of the clinical trial of the new crown vaccine of Chen Wei team: safe, can induce immune response

　　On the evening of July 20, the international academic journal "The Lancet" published online a paper on the results of the Phase II (Phase II) clinical trial of the new crown vaccine developed by the team led by Chen Wei, an academician of the Chinese Academy of Engineering and a researcher at the Academy of Military Medicine.

　　According to the latest research paper published in The Lancet, the aforementioned Phase II clinical trial of the new crown candidate vaccine conducted in China found that the vaccine is safe and can induce an immune response.

　　The researchers also pointed out in the paper that it must be emphasized that the subjects in the aforementioned clinical trials were not deliberately exposed to the risk of contracting the new coronavirus after being vaccinated. It is not yet certain whether the vaccine can effectively prevent the new coronavirus. Infection, and a Phase III clinical trial is needed to answer this question. In addition, the aforementioned test only followed subjects for 28 days, so there is no data on the durability of immunity induced by the vaccine.

　　The main purpose of the aforementioned Phase II clinical trial is to evaluate the immunogenicity and safety of the vaccine, and to provide a basis for determining the most appropriate vaccine dose for the Phase III clinical trial.

　　The aforementioned test was conducted in Wuhan in April. 508 subjects participated. 13% of the subjects were over 55 years old. 61% of the subjects were between 18-44 years old, and 26% were between 45-54 years old.

　　Among them, 253 subjects received the high-dose vaccine and injected about 1×10^11 virus particles (vaccine); 129 received the low dose, about 5×10^10 virus particles; 126 received the comfort No vaccine.

　　The results of the test showed that 95% of subjects in the high-dose group and 91% of the subjects in the low-dose group vaccinated with the aforementioned vaccines all induced T cell immune responses or antibody immune responses on the 28th day after vaccination.

　　In addition, on the 28th day after vaccination, 96% of the subjects in the high-dose group and 97% of the subjects in the low-dose group had a combined antibody immune response; the proportion of subjects with a neutralizing antibody immune response was 59. % And 47%.

　　The researchers pointed out that the subject's existing immunity to Ad5 virus (type 5 adenovirus) will affect the immune effect of the vaccine. Because an important part of the vaccine-the carrier, is the Ad5 virus. The results of the test showed that compared with subjects with higher "existing immunity to Ad5 virus", subjects with lower existing immunity had approximately higher levels of "binding antibody" and "neutralizing antibody" after the vaccine was administered double.

　　Among the 508 subjects, 266 subjects had higher pre-existing immunity, and 242 had lower pre-existing immunity.

　　In terms of adverse reactions, there were 24 subjects in the high-dose group with severe adverse reactions in the high-dose group, accounting for 9%; 1 in the low-dose group; 2 in the placebo group; the main symptom was fever .

　　The adverse reactions in most subjects were mild or moderate, such as fever, fatigue, and pain at the injection site. 72% of subjects in the high-dose group developed the above symptoms, 74% in the low-dose group, and 37% in the placebo group.

　　Compared with the Phase I clinical trial, the Phase II trial has a wider range of subjects, including people over 55 years of age. The researchers pointed out that compared with younger people, older subjects tolerated the vaccine better, but the level of immune response was relatively low.

　　Chen Wei said that once infected with the new crown virus, the elderly will face a high risk of serious illness and even death. Therefore, the elderly are an important target group for the new crown vaccine. However, it may be necessary to increase the vaccine dose to induce a stronger immune response in this population. Related research is ongoing.

　　"The vaccine is currently undergoing Phase III trials." Zhu Fengcai, deputy director of the Jiangsu Provincial Center for Disease Control and Prevention, said that compared with Phase I clinical trials, Phase II clinical trials provide the vaccine with safety and immunogenicity in a large population. evidence. This is an important step in evaluating candidate vaccines.

　　On March 16, the first phase of the clinical trial of the aforementioned vaccine was launched, with 108 subjects participating; the researchers obtained 7-day and 14-day vaccine safety data. On April 12, the Phase II clinical trial was launched, with 508 subjects participating. The vaccine was the only new crown vaccine in the world that entered Phase II clinical trials at that time.

　　"There are still three phase clinical trials to really determine the effectiveness of the vaccine. The sample size of the subjects is larger, and the scale is thousands, some even tens of thousands. For general infectious diseases, it is generally necessary to observe an epidemic cycle. Determine its protection rate for susceptible people.” On April 14, Wang Junzhi, an academician of the Chinese Academy of Engineering, said at a press conference held by the State Council’s Joint Prevention and Control Mechanism. He said that the development of the aforementioned Ad5 vector new crown vaccine is the fastest. According to the "Standards for Quality Management of Drug Clinical Trials", the usual clinical trials are divided into three phases. The subjects in the Phase I and Phase II clinical trials are all healthy volunteers, which are relatively easy to recruit. Depending on different immunization procedures and different programs, it may take several months. Generally, the scientific basis for the approval of the vaccine on the market is obtained until the final phase III clinical trial. Even in emergency situations, the evaluation criteria for vaccine safety and effectiveness cannot be lowered.

　　According to the previous report of The Paper, the aforementioned new crown vaccine developed by the team led by Academician Chen Wei is a recombinant vaccine called "Ad5 carrier new crown vaccine." Ad5 virus is a replication-defective common cold virus. In the aforementioned vaccine, the Ad5 virus is used as a "carrier rocket" to launch a new coronavirus gene-the spike gene (spike). This gene is a "satellite". Therefore, in appearance, the "Ad5 vector new crown vaccine" is a virus particle. But because part of the virus's genes are missing, it cannot replicate and rages, but it can cause an immune response.

　　There are currently about 250 new coronavirus vaccines under development worldwide, including mRNA vaccines, replicating or non-replicating viral vector vaccines, DNA vaccines, and inactivated virus vaccines. At least 17 new crown vaccines are undergoing clinical trial evaluation.

　　Reporter Lu Xinwen Yu Yan Zhu Lei