Influenza: soon a messenger RNA vaccine?

Published on : 10/15/2021 – 09:03

With the fall, the flu arrives in the northern hemisphere and, with it, the vaccination campaign. If, until now, vaccines against this virus have used well-known technologies but not 100% effective, the emergence of messenger RNA could be a game-changer.

More and more laboratories are embarking on the development of vaccines against the influenza virus using this new technology. Sanofi, the world leader in influenza, has thus started its trials for a monovalent RNA vaccine, targeting a single strain of virus, and will begin trials on a quadrivalent vaccine next year.

The American Pfizer carried out in September the first injections into humans of an anti-influenza vaccine using messenger RNA, already used in its vaccine against Covid-19. The American biotechnology company Moderna had launched its own trials in early July.

Increased efficiency

Flu vaccines have been around for a long time. However, their effectiveness is not total: they use inactivated viruses, which must be prepared well in advance, for an effectiveness which varies between 40 and 60%, or even 70%.

“Six months before the epidemic, we assess the strains that circulate the most. Sometimes we make mistakes, and this creates a significant excess mortality,” explains Claude-Agnès Reynaud, immunologist and research director at Inserm.

In addition, “the problem with inactivating a virus to prepare a vaccine is that it can damage certain surface proteins,” she says, the very ones that trigger the immune response.

Conversely, messenger RNA does not need to produce antigens (the substance foreign to the body that triggers the immune response) in millions of eggs, since it is the human cell that will produce it. even, the proteins of the virus.

“If the World Health Organization (which indicates the strains to use, Editor’s note) warns that there is a change in the prevalent strains, we will be able to change much faster with RNA than with existing technology”, emphasizes Jean-Jacques Le Fur, analyst at Bryan, Garnier & Co. With the key, increased efficiency that could reach 95%.

Many researchers are therefore on the track. Norbert Pardi, a vaccine specialist at the University of Pennsylvania, has addressed the issue in particular by formulating, using messenger RNA, several antigens in a single vaccine, which he tested in mice.

“These multivalent vaccines will probably cause an overall superior immune response” to current vaccines against influenza, he recently anticipated with AFP.

This technology nevertheless has drawbacks, including very low temperature storage conditions. “We will have to arrive at thermostable vaccines, which can be stored in the fridge at 2 to 8 degrees, in syringes. There are many things to do to succeed in converting messenger RNA to influenza”, recently explained Thomas Triomphe, the vice-president. -President of the vaccines branch of Sanofi.

Without forgetting the “question of acceptability: will the population be reassured about this technology by the time these vaccines arrive, or will they still be reluctant?” Asks Jean-Jacques Le Fur.

An attractive market

Not enough to discourage appetites, however. “Sanofi has understood that it cannot ignore this technology. Flu vaccines represent 2.5 billion euros in sales for them each year,” he adds.

“It is a very attractive market for large laboratories. Apart from Moderna, which is new in this sector, the others, such as Sanofi, AstraZeneca or GSK, are very well established in influenza”, notes Jamila El Bougrini, specialist in biotechs at the stock market analyst Invest Securities.

“This represented $ 5 billion in sales in 2020. In 2021, $ 6.5 billion or even $ 7 billion are expected,” she analyzes, with annual growth of 7 to 8% expected for the period 2020 -2026.

With AFP