Washington (AFP)

A week after recommending the authorization of a first vaccine against Covid-19, a committee of American experts met again Thursday to evaluate the remedy developed this time by the American company Moderna, with first injections expected from the next week.

Barring a huge surprise, the US Medicines Agency should give the green light to the vaccine from the young biotechnology firm shortly after this meeting, a priori as early as Friday as it had done for the vaccine from Pfizer / BioNTech.

The United States, currently facing a spectacular rebound in the epidemic, could then have two vaccines at the beginning of next week, and thus accelerate the massive vaccination campaign launched on Monday.

They would be the first to bring Moderna's vaccine to the market.

The meeting of this advisory committee will be, as it was a week ago, broadcast live on the internet, an unprecedented exercise in transparency in the world.

About twenty experts will have to confirm during a vote that the benefits provided by the injection of this vaccine outweigh the risks, in adults 18 years and over (16 years for Pfizer).

Almost no doubt hangs over the looming decision: the FDA has already found the vaccine safe and effective in a summary of data published earlier this week, about two weeks after the filing of the emergency authorization request.

The published analysis confirmed an average efficiency of 94.1%.

Out of 30,400 participants in clinical trials, 196 contracted Covid-19.

Of these, 185 had received a placebo, and 11 the vaccine (as of November 21).

In addition, the 30 cases of serious Covid-19 identified were all in the placebo group.

The most common side effects of the vaccine, called mRNA-1273, are pain at the injection site, fatigue, headaches and muscle aches, as well as joint pain and chills.

Moncef Slaoui, chief scientist of the Trump administration's Operation Warp Speed, said on Wednesday he was impressed by the level of protection against the disease already offered even after the first of two doses.

"The second very interesting thing is the protection against the infection" itself, which would be in the range of 60 to 65%, and could be higher after the second dose, he said.

One of the concerns with vaccines is that while they prevent the symptoms of the disease from developing, they do not prevent asymptomatic infection, and therefore transmission.

"It is very important from a public health point of view", underlined Mr. Slaoui.

- 200 million doses -

The US government has purchased 200 million doses of the vaccine from Moderna (100 million from Pfizer).

Since it is taken in two doses spaced four weeks apart, this corresponds to 100 million people vaccinated.

Logistics for distribution have been thought through for months.

"The bottling" takes place at subcontractor Catalent in Bloomington, Indiana, where Moderna sends large 50-liter bags of the vaccine, made in New Hampshire.

And the goal is "to have the trucks literally waiting right next to the factory to be able to load them and leave as soon as the FDA has OK", Stéphane Bancel, the boss of Moderna, told AFP.

The young company's formula has an advantage over that of its competitor: it can be stored at -20 ° C, and not -70 ° C for the Pfizer vaccine, a temperature much lower than standard freezers, and which has forced the group to develop specific containers for transport.

Moderna has promised to distribute 20 million doses by the end of December 2020, then an additional 80 million in the first quarter of 2021, and the other 100 million in the second quarter (i.e. by the end of June).

Vaccines are currently administered as a priority to the most exposed caregivers and residents of retirement homes, as recommended by US health authorities.

But Moderna also promised the thousands of clinical trial participants that they would be able to receive the vaccine within two weeks if they wanted.

In the run-up to clearance, the company sent them an email encouraging them to stay in the study, but informing them that they would be offered the option of whether they received the placebo or the vaccine - - and in the case of placebo, to be vaccinated.

Experts estimate that more than 70% of the population must be vaccinated to end the epidemic, or about 230 million people in the United States.

© 2020 AFP