The new omicron variant is a game-changer as current vaccine producers have recognized that new SARS-CoV-2 vaccines will be necessary to combat this new threat. The current vaccines offer limited protection over time against the delta variant that is now dominating worldwide and likely less protection against the omicron variant that is progressing rapidly.
The second-generation bivalent vaccine developed by Phylex BioSciences, and expected to be available in 2022, addresses specific issues created by these two variants. The mRNA vaccine encodes for a nanoparticle displaying 60 copies of the antigen based upon the receptor-binding domain of the delta and the omicron variants.
In recent animal studies, the Phylex vaccine has already demonstrated strong immunogenicity against the SARS-CoV-2 delta variant.
In virus neutralization assays and neutralization titers of Phylex vaccine-elicited sera against the SARS-CoV-2, the delta variant was up to 32-fold as compared with current mRNA vaccine-elicited sera. In another experiment, the same vaccine achieved complete protection against a delta variant infection of the lungs. These results were obtained in two independent laboratories of top-tier research institutions last month.
The same technology is being applied to the omicron variant in a bivalent vaccine. This booster candidate will offer two fundamental advantages as compared with the current mRNA vaccines. First, improved immune response against the delta and omicron variants and second, elimination of antibodies enhancing infection.
Contrary to neutralizing antibodies that are beneficial, as they neutralize a key function of the virus and prevent the infection or the disease, enhancing antibodies are detrimental and can lead to enhanced infection or disease. As published in the peer-reviewed journal “Cell” by researchers at Osaka University in June, the spike protein used in all currently approved SARS-CoV-2 vaccines elicits enhancing antibodies that increase the delta virus infectivity.
Repeated immunization with current vaccines is likely to be ineffective for the omicron variant that displays 39 mutations, deletions and insertions on the spike protein used by all current mRNA vaccines, and possibly infectivity enhancing for the delta variant.
“The resistance of the delta and omicron variants to current vaccines is due to the virus escaping neutralizing antibodies but also taking advantage of enhancing antibodies. Therefore, all currently approved vaccines worldwide, and most vaccines in the late stage of development worldwide, will not control infection effectively with the delta variant or the omicron variant”, according to Pascal Brandys, co-founder and CEO of Phylex BioSciences.
“It is now clear that there is an urgent need for booster shots with a different vaccine. Our antigen eliminates the known risk of enhanced infectivity. Moreover, our vaccine with a nanoparticle displaying 60 copies of the antigen is designed to create a strong immune response with delta and omicron neutralizing antibodies and is an excellent booster candidate for a new immunization paradigm in 2022.”
