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French vaccine giant Sanofi announced positive results of a Phase 1/2 clinical trial of its first mRNA vaccine on Tuesday, saying the early findings with a Covid-19 vaccine give the company confidence to shift gears on its mRNA program to pursue vaccines for other pathogens. The first in its sights is an influenza vaccine Sanofi hopes to begin testing in clinical trials next year.

Sanofi will not be developing an mRNA Covid-19 vaccine, Thomas Triomphe, global head of vaccines, told STAT in an interview. By the time the company could bring a Covid mRNA vaccine through the authorization process, that market will have been saturated, he said.


If Sanofi were to pursue a Covid mRNA vaccine, it would have clinical trial results to apply for a license by, at best, the last quarter of 2022 or the first quarter of 2023. By then other manufacturers could have produced in the range of 40 billion doses of Covid vaccines — enough to vaccinate everyone on earth several times over, Triomphe said. Trying to get into the market at that point “doesn’t make sense,” he said.

The company reported preliminary results from the Phase 1/2 trial that showed 91% of people who received the lowest dose tested, two doses at 7.5 micrograms apiece, saw their neutralizing antibody levels increase four-fold, a measure thought to equate to a protective level of antibodies. (Protection can only be proved in an efficacy trial comparing the vaccine to a placebo or another Covid vaccine.)

Two other dosages were tested, 15 micrograms and 45 micrograms; 100% of the people who received those two doses experienced the four-fold rise in neutralizing antibodies.


“While these are interim results and not yet final … these are confirming the fact that the mRNA platform is potent, can generate a strong immune response, [and has] no safety signal at all,” Triomphe said. “So we’re happy to see that.”

Sanofi will now accelerate its work on a previously announced mRNA vaccines “center of excellence,” he said, a project that will involve roughly 400 employees. The goal, Triomphe said, is not only to develop mRNA vaccines and therapeutics to use in ordinary times, but to be ready to produce vaccines when the next pandemic hits.

Sanofi’s mRNA work builds on a platform developed by Translate Bio, which Sanofi announced it was acquiring in August; the sale was finalized this month.

Sanofi is not alone in pursuing an mRNA flu vaccine; Moderna began a Phase 1/2 clinical trial of its mRNA flu vaccine in July. Will the platform be as successful for influenza as it has been for Covid-19? To be determined, Triomphe said. One of the key challenges of this project will be developing mRNA vaccines that do not require ultra-cold storage, ones that can be kept at fridge temperature — 35.6 Fahrenheit to 46.4 Fahrenheit.

While Sanofi aims to try to protect its important influenza vaccine business — it manufactures 40% of the global flu shot production — by exploring the mRNA platform’s potential there, it plans to push forward on production of a recombinant protein Covid vaccine, work it is doing in collaboration with GSK. The vaccine is paired with GSK’s proprietary adjuvant.

Sanofi hopes to have readouts by the end of this year on the Phase 3 trial of its recombinant vaccine as a primary Covid vaccine, as well as results of ongoing trials testing the Sanofi jab as a booster for other vaccines. The booster trials are being conducted in the United States, France, Australia, and the United Kingdom.

The company sees the potential of the recombinant vaccine to work as a sort of universal booster shot, one that can, unlike some of the other Covid vaccines, be kept at fridge temperature. If it turns out that the vaccine works well as a booster for the mRNA vaccines (those developed by Pfizer-BioNTech and Moderna) and the viral-vectored vaccines (those developed by Johnson & Johnson and AstraZeneca), family doctors could stock the Sanofi-GSK booster in their fridges and not have to worry about having multiple brands of vaccine on hand to match the original vaccine individuals received, Triomphe said.

Sanofi is also producing vaccine for three of the companies currently selling Covid-19 vaccines: Pfizer, Moderna, and J&J. The company has produced 30 million doses of the vaccines so far, but having completed the establishment and certification of the production lines expects to see output ramp up to 500 million doses by early 2022. While it has the capacity to do both this contract work and produce its own Covid vaccine, Sanofi will scale back the production for other manufacturers at a point, Triomphe said, saying “it’s really a pandemic effort.”

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