Experts: Covi vaccines come out at the earliest or at the end of the year

Reporter : Deng Anqi

Editor: Liang Xiaoling

Publisher : Ming Pao

Ref : https://news.mingpao.com/pns/%e5%89%af%e5%88%8a/article/20200720/s00005/1595183528629/%e5%b0%88%e5%ae%b6-%e6%9c%80%e5%bf%ab%e6%88%96%e5%b9%b4%e5%ba%95%e9%9d%a2%e4%b8%96-%e6%96%b0%e8%88%8a%e7%96%ab%e8%8b%97%e7%ab%b6%e8%b3%bd-%e8%b6%85%e9%80%9f%e6%8a%97%e6%96%b0%e5%86%a0

Translation, editing : Gan Yung Chyan

                                 / KUCINTA SETIA 

Images : Ming Pao

Since the outbreak of SARS-CoV-2 more than half a year ago, pharmaceutical companies and scientific researchers around the world have rushed to develop vaccines. Statistics from local scholars have found that there are hundreds of vaccines under development alone, some of which have entered Phase 3 clinical trials and are expected to be available by the end of the year.

Compared with traditional attenuated and inactivated vaccines, many vaccines under development are new vaccines. What is the difference between the production process of the new vaccine and the traditional vaccine? Will there be any security concerns?

■ Hundreds of SARS-CoV-2 vaccines

Zhang Baiheng, a research assistant professor in the Department of Chemistry at the Hong Kong University of Science and Technology, said that according to data, there are currently hundreds of covi vaccines under development worldwide, which are mainly divided into the following three categories:

1. Inactivated vaccines change S-protein, weaken virus 

 

Also known as "raw vaccine". Zhang Baiheng said that the attenuated vaccine is a weakened virus. Take SARS-CoV-2 as an example. The virus mainly invades human cell receptors with spike protein (S-protein). Researchers transplant the virus to other biological cells to change the virus's spike protein, and the virus's infectivity to humans is reduced, and a vaccine can be produced.

Examples: measles, mumps, varicella vaccines

2. Inactivated vaccines are injected into the "corpse" of the virus to evoke an immune response

Also known as "dead vaccine." Chen Jixiang, head of the Department of Microbiology at the University of China Medical School, said that researchers use chemical agents to kill viruses and then inject "corpses" into the body to stimulate the immune system. "Even if the virus remains injected into the body, the immune system will take it seriously and produce antibodies." 

Among the inactivated vaccines, some use "whole corpses" and some only take "wrecks", choosing the most toxic and infectious part. To Chen's understanding, many new coronavirus vaccines are currently researched, and only the spike protein of the virus is extracted to make an inactivated vaccine. In addition, some vaccines are made by killing the virus and then reorganizing the corpse to make it look more like a real virus, and it is more able to evoke an immune response after being injected into the body.

Examples: Hepatitis A, influenza, cervical cancer vaccines

New:

3. DNA and RNA vaccines guide cells to produce S-proteins to make antibodies

New vaccines are mainly divided into DNA and RNA vaccines. Researchers only need to know the genetic sequence of the virus. Chen Jixiang said that after the DNA/RNA vaccine is injected into the body, it can guide the body's cells to produce spike protein, stimulate the immune response and produce antibodies. The new vaccines currently under development use adenovirus as a vector. "These vectors have two functions: one is to assist in the production of viral proteins, and the other is to transport DNA/RNA to the body, where cells in the body make viral proteins."

Can be put into mass production quickly, but safety is in doubt

However, Chen added that there is currently no approved DNA/RNA vaccine that can be widely used in humans. Therefore, its efficacy and safety, lack of large-scale clinical experience and research data, still have many questions, such as: "The carrier can clamp When the DNA/RNA of the virus is delivered into the body, will it clamp the DNA/RNA of the human body? So as to produce proteins that the human body does not need?"

Now that the safety of the new vaccine is in doubt, why do researchers still work hard to develop it? The main reason is that its research and development speed is faster than traditional vaccines. Zhang Baiheng said that after the mainland announced the gene sequence of covi, researchers could produce a new vaccine within 3 to 10 hours. "Assuming that a suitable vector has already been developed, just insert the gene sequence of covi. The process of making a vaccine is very fast." On the contrary, when manufacturing traditional vaccines such as inactivated and inactivated, it takes a lot of time to study how to weaken the toxicity of the virus and select biological cells suitable for transplantation of the virus; even if the research is successful, it is necessary to solve the difficulties in the production process. , A lot of viruses need to be bred. But taking the high-risk SARS-CoV-2 as an example, Hong Kong does not have a large number of equipment for cultivating SARS-CoV-2. The only more likely place is university laboratories, but it is nowhere near the level of mass production.” .

■Expert opinions

◆Chen Jixiang (Head of Department of Microbiology, CUHK Medical School) (photo by Zheng Baohua)

◆Zhang Baiheng (Research Assistant Professor, Department of Chemistry, HKUST) (photo by Deng Anqi)