Europe 1 with AFP 8:12 a.m., September 28, 2021, modified at 8:12 a.m., September 28, 2021

Sanofi said on Tuesday to stop the development of its messenger RNA vaccine.

The laboratory will therefore not go to phase 3 of trials, the last step before marketing.

He judges that his treatment for Covid-19 would arrive too late on the market.

The Sanofi laboratory will not go to phase 3 of trials for its messenger RNA vaccine against Covid-19 - the last step before marketing -, while continuing the development of its other vaccine against the virus, has it indicated Tuesday. Despite positive intermediate results for phase 1-2 of the trial of its messenger RNA vaccine, Sanofi believes that it would arrive too late on the market, while 12 billion doses of anti-Covid vaccines will have been produced in the total by the end of the year.

The results of phase 3 on its other vaccine, based on a recombinant protein and developed with the British GSK, are still expected before the end of 2021. Initial data from the trial conducted on messenger RNA technology show seroconversion, that is, the production of antibodies, in 91% to 100% of participants, two weeks after the second injection, says Sanofi.

These positive results are verified for the three assays which were tested.

In addition, no side effects were observed and the safety profile is comparable to that of other Covid-19 RNA vaccines, such as those developed by the German-American tandem Pfizer-BioNTech and by the American biotech Moderna.

"Equip France with an arsenal of messenger RNA vaccines"

With this technology, the laboratory wanted to assess the ability to elicit an immune response.

"However, this is strong," commented Thomas Triomphe, vice president of the vaccines branch of Sanofi.

Sanofi had been working since March 2020 with Translate Bio on this vaccine, and even bought this American biotech at the beginning of August for some 2.7 billion euros.

However, "the need is not to create new Covid-19 RNA vaccines, but to equip France and Europe with an arsenal of messenger RNA vaccines for a next pandemic, for new pathologies", adds Thomas Triomphe.

Therefore, Sanofi will not develop phase 3 for this vaccine because "there is no public health need for another messenger RNA vaccine," he continues.

Sanofi, on the other hand, says it wants to develop vaccines with this technology against other viruses, without side effects and with fewer constraints in terms of storage temperature.

The group has already launched initial trials for a monovalent vaccine - with a single strain of virus - against seasonal influenza.

He said Tuesday he wanted to launch clinical trials against influenza next year, this time with a quadrivalent vaccine.