March 22-28 2021
The Pfizer-BioNTech vaccine proves effective against the UK variant
We are currently still not able to stop the spread of SARS-CoV-2, due to limited vaccination and the emergence of new variants of the virus. These variants show in the SARS-CoV-2 genome, as is the case with numerous viruses. One of these variants, the UK variant, was discovered in September 2020 in the United Kingdom. It includes a significant number of mutations (10 in the spike surface protein) and seems to be more infectious. It managed to spread worldwide and is today one of the dominant variants currently in circulation.
Several vaccines are on the market, including the first to be made available, the Pfizer-BioNtech vaccine, based on mRNA technology. This vaccine, like the others, was developed from the original SARS-CoV-2 strain that appeared in Wuhan. During phase III clinical trials, it was shown to be 95% effective in preventing COVID-19 symptoms in the case of infection by the Wuhan strain. Two recent studies, one carried out by researchers at Pfizer-BioNtech, and the other by a large international team, have shown that the Pfizer-BioNtech vaccine remains effective against the UK virus, though slightly less so.
The first investigative team from Pfizer-BioNtech used serums containing antibodies from 40 patients immunized with their vaccine. Pseudoviruses including SARS-CoV-2 spike surface proteins from the Wuhan strain or the UK variant were used in neutralization tests involving the serum of immunized patients. These pseudoviruses are study models that reproduce the entry phase into cells of complete viruses, but which are easier to manage during neutralization testing. They do not multiply and can therefore be used in laboratories having less strict biological hazard protection rules.
Researchers in the second study used the same methods as those of the Pfizer-BioNtech team. They had recourse to the serum of 37 patients inoculated with the Pfizer-BioNTech vaccine to test the neutralization of pseudoviruses covered with either spike surface proteins from the original Wuhan variant or spike proteins from the UK variant. Their conclusions were the same as those of the first team, that is, neutralization of the UK variant is less effective than in the Wuhan strain, but protection is still largely intact.
In the second study, researchers also analyzed the neutralization of the UK variant with the inclusion of the E484K mutation, a combination already observed in several patients. In the case of this variant, there was significant loss of neutralization effectiveness.
The scientists then went further with the study by using the serum of patients having been infected at the beginning of 2020, and using a mononclonal antibody. Results showed the same slight decrease in neutralization as had been observed in tests with the serum of vaccinated patients.
This can be represented as:
In conclusion, the results of the 2 studies are reassuring with regard to the protection given by the Pfizer-BioNTech vaccine against the UK variant. However, both studies are based on non-replicating pseudoviruses. This study model, which is very practical, is far removed from situations of natural infection. In any case, escape from immunity conferred by vaccines by new variants seems inevitable in the future. Since vaccination has been a key element in strategies to combat the pandemic worldwide, it seems important to adapt existing vaccines to deal with new variants. Those based on mRNA technology are likely to be easier and therefore faster to adapt to new mutants.