Scientific and medical research is not made only of successes, but rather of a succession of failures and successes which allow permanent adjustments and questioning. This is evidenced by recent news from the Institut Pasteur, which announced, this Monday, January 25, the end of the development of its main vaccine project against Covid-19.
An insufficient immune response
The reason for such a decision can be summed up in one word: efficiency. “The decision not to pursue the development of the vaccine candidate based on the measles vaccine virus follows the examination of the interim results obtained in the context of phase I trials, initiated since last August”, Details the Pasteur Institute in a press release. “In these first-dose studies in humans, the vaccine candidate was well tolerated, but the induced immune responses were found to be lower than those observed in people cured of a natural infection as well as those observed with the authorized vaccines against SARS-CoV-2 / Covid-19”, He explains.
The phase I clinical trial that began last August included 90 healthy volunteers, randomly and blindly divided into two groups: some received two doses of the vaccine candidate while others received two doses of the vaccine. ‘a placebo. Unfortunately, the immune response elicited by the vaccine candidate was well below expectations, and arguably “well below the 50% efficiency required by the[Organisation mondiale de la santé”, a commenté Christophe d’Enfert, directeur scientifique à l’Institut Pasteur, cité par Le Figaro.
A different technique from that of messenger RNA
This vaccine candidate was based on a technique called “classic”Development of a vaccine, different from that of the messenger RNA of the Pfizer / BioNTech and Moderna vaccines currently marketed in Europe. The virus used in the measles vaccine was here used as “vehicle”, Allowing the construction of recombinant vaccines, especially against dengue. The recombinant vaccines thus constructed could then expressing antigens (fragments recognized by our immune system) of various pathogens, in this case Sars-CoV-2.
Note that this approach should not, however, be abandoned, since it has given good results for the development of a chikungunya vaccine candidate, which has “obtained positive results in phases I and II, the elements of which have been published in the Lancet paving the way for a phase III trial”, Notes the Institut Pasteur.
Two other vaccine candidates at the preclinical stage
Although it is abandoning this project, the Institut Pasteur is not giving up on the development of a vaccine against Covid-19. He specifies that he “will continue to develop other vaccine candidates at the end of the preclinical phase, and maintain its strong scientific mobilization to fight the Covid-19 epidemic”.
The Institut Pasteur will continue its research into two other vaccine candidates based on different methodologies: the first, which can be administered by the nasal route, is being developed with the biotechnology company TheraVectys, a member of the Institut Pasteur and specializing in the development of vaccines, while the second is a DNA vaccine candidate. Both are currently in the preclinical phase, i.e. tested in vitro and in vivo, on animal models.
Source: Pastor Institute
To find out more about the coronavirus, the editorial staff invites you to discover its more complete and regularly updated articles:
- an article on Covid-19 disease and the evolution of the epidemic
- an article on the different screening tests
- an article on vaccines under development.