- The American company Moderna has announced the start of phase 3 of the clinical trial of its Covid-19 vaccine.
- An RNA type vaccine, very different from conventional vaccines, which has never worked before.
- If the effectiveness of this remedy and its tolerance by men are proven, Moderna hopes to put its vaccine on the market by the end of the year and produce considerable stocks quickly.
More than two hundred teams of researchers are currently working hard to develop a vaccine against the coronavirus. In this frantic international race, in which twenty vaccine candidates are at an advanced stage, the Americans of Moderna biotech have just placed themselves in pole position by announcing the launch of phase 3 of the clinical trial of their vaccine. 20 Minutes explains what you need to know about their work, bringing hope in the fight against Covid-19, while in several countries the health battle resumes more beautifully faced with an increase in the number of cases.
The first vaccine tested on humans
The biotechnology company Moderna Therapeutics was the first to test a vaccine against Covid-19 in May. This Tuesday, the American firm announced that it would enter on July 27 in phase 3 of its clinical trial to test the effectiveness of its vaccine in real conditions on 30,000 people in the United States. A final step scheduled following the promising results of the first phases of tests, co-funded by the United States government. This research project is far from trivial since it involves validating the first mRNA vaccine for human use. An innovative type of remedy that differs from traditional vaccines and is much faster to develop.
Innovative technology
A classic vaccine consists in inoculating a part of the weakened or dead virus in humans in order to stimulate the body's immune defenses. The white blood cells then make antibodies that will help fight this virus when the body is confronted with it. The messenger RNA vaccine, on the other hand, consists in inoculating a part of the genetic code of the virus and not the virus itself. If it works, the body will temporarily start to produce a protein from the virus, protein S in the case of Covid-19. "This will provoke an immune reaction from the (vaccinated) host which will make antibodies against this protein, and therefore against the virus", underlines Professor Daniel Floret, president of the technical committee of vaccinations at the High Authority for Health.
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Promising results
The results of phases 1 and 2 of the clinical trial conducted in recent months in the United States by the firm and published on July 14 in the New England Journal of medicine are promising. In phase 2, 45 participants were injected with two doses of the vaccine candidate 28 days apart. After the second dose, participants had higher levels of antibodies than most patients who had Covid-19 and generated their own antibodies, according to Moderna. More than half of the subjects developed mild or moderate side effects, considered normal, such as chills, headache or fatigue.
What to expect from the final phase?
The phase 3 clinical trial is essential and decisive. It must demonstrate the efficacy and tolerance of Moderna. Of the 30,000 participants, one part will receive the vaccine, the other a placebo. It will then be a question of verifying who subsequently made an infection to measure the efficiency of the RNA. "The effectiveness of the vaccine can be expressed in two ways," continues the professor. Ideally, it will help prevent infection. ” This would block the transmission of the virus. It is also possible, according to the researchers, that the vaccine does not prevent being contaminated but blocks the development of symptoms of Covid-19. "It would be less good but useful anyway," observes Daniel Floret. This final step should also ensure that the vaccine does not generate serious adverse effects.
What reservations do I have about this vaccine?
In the midst of a pandemic, caution obviously remains in order not to raise false hopes. “The firm hopes for results that will allow it to be marketed before the end of the year. But we don't know. Perhaps the trial will show that the vaccine does not work. Everything is possible. We have to be careful. It would not be the first time that a vaccine candidate does not work or has serious side effects. We have already seen it for other diseases, whereas during the first phases of the tests, we could have had some interesting elements, ”recalls Professor Floret. On the other hand, if phase 3 proves conclusive, it will be a real “wonder”, according to the pediatrician. "We started from scratch and making a vaccine in a few months would be unheard of, great news."
When to expect a successful marketing?
The clinical trial is expected to deliver its first results in the fall. If the Moderna vaccine is proven, then the company will need to obtain marketing authorization. In the United States, this burden falls to the FDA. In Europe, the European Medicines Agency will have to examine the results of the trial to decide whether or not to grant a marketing authorization. A decision ultimately acted on by the European Commission. It is likely that, if successful, the authorization will only be temporary, long enough to assess the vaccine's efficacy and its tolerance in humans over the long term. The participants in the trial must also be followed until the fall of 2022. "If the test is positive, we will not immediately know how long the vaccine protects. This is important data and we can only know it with follow-up. This monitoring will also make it possible to see if there are no possible delayed undesirable effects ”, underlines the expert in vaccinology.
A type of quick vaccine to make
If the American company manages to pass the last stages until the marketing of its vaccine, it hopes to produce a considerable stock of vaccines. Moderna has planned to be able to produce 500 million doses per year, and "possibly up to 1 billion," recalls AFP. Massive production made possible by this type of remedy, much faster to develop than a traditional vaccine. “For a conventional vaccine, you have to isolate the virus, inactivate it, check that it is inactivated but that it retains its immunological properties. It takes years. While making nucleic acids, like an RNA vaccine, is very easy to do. The big advantage also is that it should allow very rapid production of very large doses of vaccines, ”concludes Professor Floret.
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