American biotech Moderna announced Tuesday that it would enter the final phase of its clinical trials for a vaccine against Covid-19 on July 27, in order to test its effectiveness under real conditions. The announcement came at a time when the results of the first phase of the Moderna trial, which aimed to verify that the vaccine was safe and that it triggered the production of antibodies, were published.
Critical, phase 3 of the trial, which will therefore be launched at the end of the month, will appeal to 30,000 people in the United States: half of them will receive a dose of 100 micrograms, the others a placebo. The researchers will then follow them for two years to determine if they are protected from infection with SARS-CoV-2. Or, if they are still infected, if the vaccine can prevent progression to symptoms.
What efficiency?
Even if symptoms are seen, the vaccine can be considered successful if it prevents severe cases of Covid-19. The study is expected to last until October 27, 2022, but preliminary results are expected to be released well before that date. The announcement places Moderna in the lead in the global race for a vaccine against the disease, which has infected more than 13 million people worldwide and killed more than 570,000 people. Scientists warn, however, that the first vaccines to hit the market are not necessarily the most effective or the safest.
Moderna Phase 1 results show coronavirus vaccine safe, induces immune response https://t.co/UUN1PqnB92 pic.twitter.com/s7XjXQLLnh
- Reuters (@Reuters) July 15, 2020The announcement was made shortly after the publication in the New England Journal of Medicine of the results of the first phase of the Moderna trial, according to which the experimental vaccine had raised antibodies against the coronavirus in all participants, number 45. Moderna released the “interim results” of this Phase 1 in May, according to which the vaccine had provoked an immune response in eight patients.
These results had been called "encouraging" by immunologist Anthony Fauci, and the full study was eagerly awaited by the scientific community. According to the article published Tuesday, the 45 participants in Phase 1 were divided into three groups of 15, to which doses of 25 micrograms, 100 micrograms and 250 micrograms were administered. They received a second dose, in the same amounts, 28 days later.
After the first administration, it was found that the antibody levels were higher with the higher doses; after the second, participants had higher antibody levels than most of the patients who had Covid-19 and generated their own antibodies. More than half of the participants experienced mild or moderate side effects, which is considered normal. These side effects include fatigue, chills, headache, and pain where the vaccine was injected.
High levels of antibodies
Three participants did not receive a second dose. One developed redness on both legs, and the other two missed the window of opportunity because they developed symptoms of Covid-19. However, their tests were negative. Amesh Adalja, an infectious disease specialist at Johns Hopkins University, said that the participants were encouraged to have developed high levels of antibodies.
But "you really have to limit the extrapolations from a phase 1 clinical trial, because we want to see how it works when a person is exposed to the real virus," he added. And Moderna's technology, based on messenger RNA, has never proven effective against other viruses. It aims to give the body the genetic information necessary to trigger preventive protection against the coronavirus.
Previous work using this technology had the opposite effect as desired, making recipients more susceptible to infection, said David Lo, a professor at the University of California Riverside. "One of the things that we have to watch out for is whether there is a long-term effect where the immune response (…) potentially develops an immunological tolerance which would in fact be harmful for protection", he said. -he says.
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