Coronavirus COVID-19 vaccine can be said to affect the hearts of people around the world, so when will the COVID-19 vaccine be ready?
However, according to Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases (National Institute of Allergy and Infectious Diseases), a COVID-19 may take 12 to 18 months to develop, test, and Approved for public use. But it usually takes several years for new vaccines to be approved, so do we really hope to develop a coronavirus vaccine in the summer of 2021? Experts say that this time plan is unrealistic for any other vaccines . But considering the current pressure to avoid the flu pandemic, as long as scientists and regulatory agencies are willing to take shortcuts, a COVID-19 vaccine may be developed soon. This is why it cannot be developed before 12 to 18 months. According to the World Health Organization (World Health Organization), there are more than 60 candidate vaccines under development worldwide, and several of them have been tested in early clinical trials on human volunteers.
The goal of some organizations is to induce an immune response by introducing a weakened or dead SARS-CoV-2 virus or virus fragment into the immunized population. According to the U.S. Department of Health & Human Services, vaccines for measles, influenza, hepatitis B, and the vaccinia virus that causes smallpox all use these methods. Despite the trials and tests, using this method to develop these traditional vaccines is a labor-intensive task that requires scientists to isolate, cultivate and modify live viruses in the laboratory.
Considering the current time constraints, some groups got rid of traditional concepts and chose a faster method.
For example, the first COVID-19 vaccine that entered clinical trials in the United States used a genetic molecule called mRNA as its basis. Scientists produce this mRNA in the laboratory, instead of directly injecting SARS-CoV-2 into the patient's body, but introducing this mRNA into the patient's body. According to the design, this vaccine should be able to encourage human cells to build proteins on the surface of the virus, thereby triggering a protective immune response against the coronavirus. The goal of other research groups is to use related genetic material, including RNA and DNA, to create similar vaccines that interfere with the early steps of the protein construction process. But messenger RNA vaccines have a big unknown, that is, we are not sure they will work.
scientists said that so far, no vaccine made from bacterial genetic material has been approved. Although this technology has existed for nearly 30 years, RNA and DNA vaccines have not yet reached the protective capabilities of existing vaccines.
assumes that these non-traditional COVID-19 vaccines have passed the initial safety test. "Will it be effective?" This is still an unknown. Even if
is used to measure efficacy in animal research and early clinical trials-whether a vaccine can cause an adequate response of the human immune system-it needs to be clearly defined. In other words, researchers should be able to use these early studies to determine which vaccines can continue to be used, which need to be modified, and which need to be abandoned. Pavlovsky said that the entire process from laboratory petri dishes to animal experiments may take 3 to 6 months. Challenges of vaccine development
However, we must be clear that it is not easy to design a vaccine that can enhance immunity and minimize side effects. Especially the coronavirus vaccine has huge challenges. Although scientists did create vaccine candidates for the coronaviruses SARS-CoV and MERS-CoV, these vaccines did not withdraw from clinical trials or enter public use, partly because of lack of resources. And the key is to deal with the coronavirusIn the case of viruses, some vaccines can cause a dangerous phenomenon called antibody dependence enhancement (AED). This is contradictory. It makes the human body more susceptible to serious diseases after vaccination.
For example, dengue virus vaccine candidates produce low levels of antibodies, which will guide the virus to attack vulnerable cells instead of destroying the pathogen at the first sight. According to a review article published in the journal Nature on March 16, the coronavirus vaccine for animal diseases and the human disease SARS have caused similar effects in animals. Therefore, some people are worried that a candidate SARS-cov -2 The vaccine may have the same effect. Therefore, scientists should observe signs of AED in all upcoming COVID-19 vaccine trials. It is determined in the initial animal experiments whether enhancement will occur, but how we look for AEDs is still unclear, which is one of the key issues.
But once there is a good animal model that can show symptoms after SARS-CoV-2 infection, we can know whether vaccination will reduce or enhance the pathogenesis. But testing these may take months of long-term research. Therefore, AED research can be conducted simultaneously with other animal experiments to save time.
Another point is that we know that the development of a successful coronavirus vaccine will curb the spread of SARS-CoV-2 by reducing the number of new infections. COVID-19 infection usually occurs in the mucosal tissues of the upper respiratory tract. In order to effectively prevent the spread of the virus, you need to have immunity at the infected site, in the nose, and in the upper respiratory tract.
is easily penetrated by infectious pathogens because of these initial hot spots. Therefore, we need a special immune cell fleet, separated from the cells that patrol the whole body tissues, and responsible for protecting these fragile tissues. The immune cells that protect mucosal tissues are produced by nearby lymphocytes. But not all vaccines can cause a strong response from the mucosal immune system, he said. For example, seasonal influenza vaccines cannot reliably trigger mucosal immune responses in all patients, which explains to some extent why some people still get respiratory diseases after vaccination.
Even if the COVID-19 vaccine can initiate the necessary immune response, researchers are not sure how long this immunity will last. He said that although studies have shown that coronaviruses will not mutate quickly, seasonal coronaviruses will appear every year, and they will not change much every year. "Although the shape of the four types of coronaviruses has hardly changed, they will cause common Catch a cold and constantly infect humans-so why haven’t we built an immune system?
Scientists believe that the virus itself is a bit strange, especially in its antigens. The viral protein can be recognized by the immune system and cause immunity. In addition, the coronavirus may interfere with the immune system itself in some way, which can explain the decline in immunity over time. Therefore, in order to ensure that the vaccine can provide long-term immunity to SARS-CoV-2, scientists will have to resolve These problems. In the short term, they will have to design experiments to challenge the immune system after vaccination and test its flexibility over time. For example, in a mouse model, such research will take at least a few months. Scientists cannot Similar experiments are carried out on humans, so this time will only be longer. The choice of
test population is
and unlike the antiviral treatment of COVID-19 that can be used for patients who have been infected with the virus, the vaccine must be tested in different healthy people. Because it is absolutely safe to give this drug to healthy people, it will face tremendous pressure. More importantly, the vaccine must be effective for people of many ages, including the elderly, whose weak immune system makes They are at high risk of severe COVID-19 infection.
So initially, this safety study will be conducted on a small number of people, maybe less than 100 people, and then a vaccine may be approved on the basis of these small studies. The study may last for several months, and then continue to be monitored as more people are vaccinated. Of course, this is only the expectation of scientists.
COVID-19 vaccine phase test
First of all, experts said that with the US Food and Drug Administration (FDA) Cooperation with other regulatory agencies can help scientists leapfrogLogistical obstacles, such as recruiting healthy volunteers, can save six months.
Any possible vaccine needs to pass a safety test, the first phase test, which also helps determine the required dose. The next step is a larger experiment, with 100 to 300 subjects, called the second phase. The second phase will look for some biological activity, but it is not certain whether the drug is effective. If a candidate vaccine elicits a promising immune response in the second phase of clinical trials, and passes the safety test in the first phase, then the FDA may approve it "before the 18-month deadline I call" Emergency use of vaccines. Subsequently, under normal circumstances, the vaccine will enter the third phase of clinical trials, including hundreds to thousands of people.
Therefore, adding these steps together, each one may take 3 to 6 months. We are unlikely to find a safe and effective vaccine in less than 12 months, even if many of these steps can be performed at the same time. It is impossible to proceed. The next problem for
is to produce billions of doses of new vaccines, the ingredients of which we do not yet know. According to reports, Bill Gates stated that the Gates Foundation will fund the construction of plants for seven candidate coronavirus vaccines so that these plants can produce multiple vaccines.
In any case, research on coronavirus immunity should continue, not only for COVID-19, but also for the next possible coronavirus.
