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The spread of the new crown epidemic worldwide has brought huge challenges to the world. People’s Hopes and needs are becoming more and more urgent. In order to do this as soon as possible, a company is skipping the early testing steps and fast-tracking a vaccine technology that has not yet proven effective in humans.
"During difficult times, we may do what we can't do in normal times," said Michael Diamond, a viral immunologist at Washington University School of Medicine in St. Louis, Missouri. "A moment of despair requires Risky measures. ”
When most companies and academic groups just started to develop vaccines, Moderna, a biotechnology company based in Cambridge, Massachusetts, was already providing health participantsInject experimental vaccines.
The vaccine represents the best long-term defense against the SARS-Cov-2 virus and may help stop the virusOutbreak in the future. But public health experts say that even if a vaccine is proven to be safe and effective in preventing infection, it will take at least a year to be promoted, which is already very rapid for vaccine development.
A few weeks after China shared the genetic sequence of the coronavirus in January, Moderna announced that it would ship experimental vaccines to the US government for testing. Not long ago, some volunteers in Seattle became the first people to receive this vaccine. Over the next six weeks, a total of 45 healthy adults between the ages of 18 and 55 will receive the study vaccine.
This initial human study, called a phase one trial, will test the safety of the vaccine and its ability to generate an immune response at three different doses. An effective vaccine must be able to produce a mimic infection in the human body but not make people sickimmune response.
Moderna made vaccines so quickly, they skipped laboratory experiments. Usually, scientists areVaccines must be tested on animals before human testing, but the US Food and Drug Administration has allowed Moderna to conduct animal tests at the same time as human safety tests.
Dr. Nathan Elderman, an infectious disease physician at the University of Alabama at Birmingham, said that in a public health crisis, this decision makes sense. "Fortunately, we have an opportunity in this regard. Based on the experience of SARS and MERS, people have been working on developing methods for the immune response of the coronavirus vaccine for some time."
The viruses that cause SARS (Severe Acute Respiratory Syndrome) and MERS (Middle East Respiratory Syndrome) are also coronaviruses. These scientists have provided a starting point for the rapid development of coronavirus vaccines. Moderna is already working with researchers from the National Institute of Allergy and Infectious DiseasesTeam members to develop an experimental MERS vaccine.
Coronavirus has a spherical shape with protein spikes on the surface. These spikes will target human cells, allowing viruses to enter and infect them.
Moderna is developing a vaccine consisting of a small piece of genetic material, which is called messenger RNA, which creates a kind of The harmful spike protein provides instructions. RNA is packaged into nanoparticles as a vaccine. (Unlike other vaccines, this vaccine does not contain part of the actual pathogen.)
Once in the human body, the vaccine can stimulate the cells to produce some harmless spikes protein. If the spike protein is successfully produced, the immune system will recognize that the spike protein is foreign and release antibodies to attack them. These antibodies will continue to exist in the human body, and if a person is exposed to the virus in the future, they will not be infected.
Even if there is no vaccine using this method currently on the market, it does bringHope. So far, this vaccine—RNA vaccine—has only been tested in humans in small-scale safety trials. Scientists actually don't know how effective the vaccine is in the human body.
Diamond said that in previous animal experiments, the antibody levels produced by RNA vaccines were "in the same range" as other types of vaccines. Diamond is a member of Moderna's scientific advisory committee and worked with the company to develop an RNA vaccine against the Zika virus. Compared with current vaccines, RNA vaccines have some advantages. "The development and deployment of RNA vaccines is very rapid," he said.
The preparation process of RNA vaccine is much faster than other methods. Moderna can manufacture the vaccine within a few weeks and ship it to the National Institutes of Health for testing.
Elderman said: "Even the production of a flu vaccine takes months, and we know very well what we are doing every year."p>
The production cost of this vaccine is also quite low, because the production cost of RNA in the laboratory is very low. In addition, some scientists believe that the risk of serious side effects is very low due to the body's own production of protein. However, since these vaccines have not been extensively tested in humans, their side effects are still unclear.
Karen Musk, a research scholar at the Hasting Center for the Garrison Institute for Bioethics in New York, said that the vaccine is for healthy people, which means Safety standards must be very high. "People who participate in the first human experiment usually have an altruistic mentality, but they must understand the risks they take."
Participants in the vaccine experiment will Receive two vaccine injections in the upper arm about a month apart, and the researchers will continue to track negative side effects. if there is no problem, Then the test scale will continue to expand to ensure that it is effective in preventing the spread of the epidemic. This will take several months.
The U.S. Food and Drug Administration (FDA) will ultimately determine whether the vaccine is safe and effective, and whether it should be approved. Dr. Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases, said that a vaccine can be promoted and it will take at least 12 to 18 months to be ready.
RNA vaccine expert Dr. Drew Weissman said, "This is very fast," and he developed the technology being used by Moderna in the University of Pennsylvania laboratory . "The approval of a new vaccine usually takes about 5 years." He said that the difficulty of making vaccines lies in their ability to work. "You have to conduct human experiments in a large group of people and follow up to determineWhether the population is free from disease. It is not easy to speed up at this step. "
Musk said that scientists and regulators must decide whether the vaccine is effective. For example, the measles vaccine is 93% effective in preventing diseases. Compared with, The current influenza vaccine is 45% effective in preventing influenza virus strains from 2019-2020.
Is this enough for the coronavirus vaccine? Scientists don’t know yet. Musk said: "If some substances are effective, but the results are not so effective, this may give people false hope. ”
Considering the infection of coronavirus Sex, it is likely that a large proportion of people will be vaccinated to prevent future outbreaks. This idea is called herd immunity. For measles virus, about 90% to 95% of the population must be vaccinated to achieve herd immunity and prevent epidemics. Outbreak. However, the herd immunity threshold of the coronavirus is unclear.
Elderman said: "There is no doubtIf there is a vaccine that can not only establish protection for individuals, but also increase the potential for herd immunity and prevent the ability of the coronavirus to produce productive infections, it will be very helpful. "
At the same time, the German company CureVac is also developing an RNA vaccine. According to the New York Times, the Trump administration is trying to persuade the company to transfer its work To the United States. Another German company BioNTech and pharmaceutical giant Pfizer (Pfizer) in cooperation to develop an RNA vaccine. Other companies and academic laboratories are studying different vaccine methods.
Even if scientists can develop an effective coronavirus vaccine in record time, there may be another major obstacle.
Coronavirus is an RNA virus, which meansIt means that their genetic material is composed of RNA instead of DNA. It is well known that RNA viruses have a higher mutation frequency than DNA viruses, such as those that cause chickenpox, herpes and smallpox.
Coronavirus may mutate into different strains and continue to spread in a seasonal manner, similar to influenza. If this happens, scientists must come up with a new coronavirus vaccine formula every year, just like the flu vaccine currently used.
"If we develop a vaccine that is effective against the original strain, how effective is the vaccine against future mutations of the strain?" Elderman said . "I don't know the answer."
But if an RNA vaccine Effective, it can be made quickly and cheaply, so it is easy to produce vaccines against different coronavirus strains and new pathogens that may appear. What needs to be done is to correspond to new pathogens and exchange matching genetic materials.
Of course,Sufficient vaccines are also needed. Some people say that government funding can be used to help promote the production of coronavirus vaccines and the vaccines needed in future outbreaks.
"Humans will always face new sources of infection," Elderman said. "Investing in a meaningful way will make us better prepared for what will happen again in the end."
Humanity and Infection The fight against disease has never stopped, and what we are doing now is not only to survive this epidemic, but also to prepare for the next fight.
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