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Is the Pfizer-BioNTech vaccine one step ahead?

As SARS-CoV-2 continues to spread, new variants carrying mutations are emerging. These mutations, especially in the spike (S) surface protein, may lead to increased virus transmissibility. They can also engender resistance to current vaccines, such as the Pfizer-BioNTech mRNA vaccine, which was the first vaccine to be authorised for use. Some variants that have emerged recently, such as the Delta variant (δ, Indian, which exists in various forms: B.1.617.1, B.1.617.2, B.1.617.v2 and B.1.618) and the B.1.525 (Nigerian) variant are being closely monitored. Researchers at the University of Texas (Department of Medicine, Galveston, USA) and the Pfizer and BioNtech laboratories have evaluated the efficacy of this vaccine against the new variants.

The researchers first of all took serum (containing antibodies) from 20 patients vaccinated with the Pfizer-BioNTech vaccine. They then analysed the neutralisation of the variants by antibodies using pseudoviruses, laboratory-produced viral particles carrying SARS-CoV-2 S surface proteins that are unable to replicate. They studied five types of pseudovirus: the Nigerian variant and 4 different strains of the Delta variant (which carry several different mutations).

The vaccinated patients’ serum enabled all the tested variants to be neutralized. The B.1.525 (Nigerian) variant was satisfactorily neutralised by the antibodies of vaccinated individuals even though a slight lessening of neutralisation was observed as compared with the original strain of the virus. Regarding the Indian variants, only one of these strains (B.1.617.1) appeared to be significantly more resistant to neutralisation by antibodies, while the other 3, like the Nigerian variant, showed only minimal resistance.

So the Pfizer-BioNTech vaccine does remain effective overall against these new variants. While the virus continues to spread, other mutant strains will emerge, but at the moment, nothing leads us to believe that they will be able to fully escape vaccinal protection. It is therefore essential that the proportion of fully vaccinated people in the population continues to rise.

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