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Paris (AFP)
The coronavirus variant detected in South Africa poses a ‘significant risk of reinfection’ and raises concerns about the vaccine’s effectiveness, preliminary research showed Wednesday, as separate studies suggest the British strain would likely be limited by vaccinations .
Several new variants – each with a cluster of genetic mutations – have emerged in recent weeks, sparking fears about an increase in infectivity as well as suggestions that the virus could begin to elude the immune response, whether in from a previous infection or vaccine.
These new variants, detected in Great Britain, South Africa and Brazil, present mutations in the spike protein of the virus, which allows the virus to attach itself to human cells and therefore plays a key role in the spread of diseases. infections.
But it is one mutation in particular – known as E484K and present in variants detected in South Africa and Brazil but not the one in Great Britain – that is of particular concern to experts on the “leak” of immunity. .
In a new study, which has not yet been peer-reviewed, South African researchers tested the variant found there – called 501Y.V2 – against blood plasma from recovered Covid-19 patients.
They found it to be resistant to neutralizing antibodies created by a previous infection, but said more research was needed on the effectiveness of other parts of the immune response.
“Here, we show that the 501Y.V2 line, which contains nine spike mutations and rapidly emerged in South Africa during the second half of 2020, is largely resistant to neutralizing antibodies caused by infection with previously circulating lines” , said the authors.
“This suggests that despite the many people who have already been infected with SARS-CoV-2 around the world and who are presumed to have accumulated some level of immunity, newer variants such as 501Y.V2 pose a risk of reinfection. important.”
The researchers added that it could also affect the use of convalescent plasma as a treatment for Covid-19. They also suggested that this could have “implications” for vaccines developed based on immune responses to the virus spike protein.
Trevor Bedford of the Fred Hutchinson Research Center tweeted that this variant could “spread more widely in the coming months.”
If the results of the South African study are confirmed, he said it may be necessary to adapt the viral “strain” used to develop the vaccine by the fall of this year.
The results are “not good news, but it is not unexpected,” James Naismith, director of the Rosalind Franklin Institute, said in comments to the Science Media Center.
He said real-world immune responses were more complex than those of blood plasma neutralizing antibodies.
“Vaccines stimulate very strong responses, immunity is a sliding scale, it is not an on / off switch,” he added.
– UK strain –
Two other preliminary studies published online Wednesday found that antibodies from previously infected patients are largely effective against the variant detected in Britain and that the BioNTech / Pfizer vaccine also appears to protect against it.
The researchers said their early findings on the rapidly spreading strain, known as B.1.1.7, suggested that the variant would not be able to escape the protective effect of current vaccines.
“Our results suggest that the majority of vaccine responses should be effective against the B.1.1.7 variant,” UK and Dutch researchers concluded in one of the studies.
The authors tested the British strain in the laboratory with antibody-rich blood plasma from 36 patients who had recovered from mild or severe forms of Covid-19 and found that most were able to neutralize the variant.
A separate study by researchers at BioNTech and Pfizer compared the neutralizing effect of plasma from 16 participants in their vaccine clinical trials to the British variant and the original virus that emerged in Wuhan, China.
They concluded that it was “unlikely” that the B.1.1.7 variant could escape the immune protection of the vaccine.
© 2021 AFP
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