South African virus strain presents ‘risk of reinfection’: study

The coronavirus variant detected in South Africa poses a “significant risk of reinfection” and raises concerns about the vaccine’s effectiveness, according to preliminary research on Wednesday, as separate studies suggested that the British strain would likely be restricted by immunizations .

Several new variants – each with a group of genetic mutations – have emerged in recent weeks, raising fears about an increase in infectiousness, as well as suggestions that the virus could begin to escape the immune response, whether from a previous infection or a vaccine .

These new variants, detected in Britain, South Africa and Brazil, have mutations in the virus’s spike protein, which allows the virus to attach to human cells and therefore plays a key role in driving infections.

But it is a particular mutation – known as E484K and present in variants detected in South Africa and Brazil, but not in Great Britain – that has specialists particularly concerned with the “escape” of immunity.

In a new study, which has not yet been peer-reviewed, researchers from South Africa tested the variant found there – called 501Y.V2 – against blood plasma from recovered COVID-19 patients.

They found he was resistant to neutralizing antibodies created from a previous infection, but said more research is needed on the effectiveness of other parts of the immune response.

“Here we show that the 501Y.V2 strain, which contains nine peak mutations and emerged rapidly in South Africa during the second half of 2020, is largely resistant to neutralizing antibodies elicited by infection with previously circulating strains,” said the authors.

“This suggests that despite the many people who have already been infected with SARS-CoV-2 globally and are presumed to have accumulated some level of immunity, new variants like 501Y.V2 present a significant risk of reinfection.”

The researchers added that this may also affect the use of convalescent plasma as a treatment for COVID-19. They also suggested it could have “implications” for vaccines developed based on immune responses to the virus’s 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 “strain” of the virus used in the development of the vaccine by the fall of this year.

The findings “are not good news, but they are not unexpected,” said James Naismith, director of the Rosalind Franklin Institute, in comments to the Science Media Center.

He said that real-world immune responses are more complex than those of neutralizing antibodies in blood plasma.

“Vaccines stimulate very strong responses, immunity is a sliding scale, not an on / off button,” he added.

United Kingdom strain

Two other preliminary studies published online on Wednesday found that antibodies from previously infected patients are largely effective against the variant detected in Britain and that the BioNTech / Pfizer vaccine appears to protect against it as well.

The researchers said their first discoveries about the fast-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 most responses to the vaccine must be effective against variant B.1.1.7,” concluded researchers from Britain and the Netherlands in one of the studies.

The authors tested the UK strain in a laboratory with antibody-rich blood plasma from 36 patients who 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 clinical trials of vaccines against the British variant and the original virus that emerged in Wuhan, China.

They concluded that it was “unlikely” that variant B.1.1.7 could escape the immunological protection of the vaccine.

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© 2021 AFP