Washington (AFP)

US biotech Moderna announced Tuesday that it will enter the final phase of its clinical trials for a Covid-19 vaccine on July 27, after the publication of promising preliminary results.

Critical, phase 3 of the trial 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 primary goal of this trial will be to find out if the vaccine is safe and prevents SARS-CoV-2 infection. If a person is still infected, the question will also be whether the vaccine can prevent progression to symptoms.

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.

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.

It comes after Tuesday's 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 has raised antibodies against the coronavirus in all the participants, 45 in number.

- What efficiency? -

The Chinese company SinoVac is also at an advanced stage of research, and the Russian agency TASS has announced that Russian researchers have completed clinical trials for a vaccine, but they have not released the data.

Scientists warn, however, that the first vaccines to hit the market are not necessarily the most effective or the safest.

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.

Moderna had released the "interim results" of its Phase 1 in the form of a press release on its site 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.

The company has since moved on to the next stage of its test, with 600 people.

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 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, but these did not reach the level at which the trial should have been canceled.

These side effects include fatigue, chills, headache, and pain where the vaccine was injected.

Three participants did not receive a second dose. One of them developed redness on both legs, and two others missed the window of opportunity because they developed symptoms of Covid-19. However, their tests were negative.

Moderna is among the very first in the global vaccine race, receiving $ 483 million from the United States government.

If the dose chosen for the tests (100 micrograms) proved effective, Moderna planned to be able to produce 500 million doses per year, and "possibly up to 1 billion".

© 2020 AFP