select search filters
roundups & rapid reactions
before the headlines
Fiona fox's blog

expert reaction to preprint reporting that the South African SARS-CoV-2 variant 501Y.V2 escapes neutralisation by COVID-19 donor plasma

A preprint, an unpublished non-peer reviewed study, suggests that the South African variant of SARS-CoV-2, 501Y.V2, escapes neutralisation from antibodies in COVID-19 convalescent plasma.


Dr Julian Tang, Honorary Associate Professor/Clinical Virologist, Respiratory Sciences, University of Leicester, said:

“At first, the abstract to this paper seems very alarming, where the South African 501Y.V2 variant can escape neutralising antibody responses – due largely to the presence of the E484K and K417N mutations, which are also found in the Brazilian variant but not in the most widespread UK variant. This may reduce some efficacy from S-protein-based vaccine-induced antibodies in some people.

“However, later on, when discussing the convalescent plasma results (which are based on natural infection and exposure to the whole virus and all its proteins), the study notes considerable binding to the 501Y.V2 virus via other non-neutralising antibodies – which can still offer some significant protection against this virus variant.

“The study also acknowledges that it cannot assess the impact of this virus variant on T-cell responses (which act in a different way to antibodies) – so some additional defense will arise from this, as well as other naturally existing innate components of the immune system in those infected – in addition to any residual vaccine protection.

“Further real life studies will be needed to assess the true impact of this South African 501Y.V2 variant on the vaccinated South African population outside of a laboratory context – and in the presence of other natural human immune responses.

“In the mean time, we still need to continue with the COVID-19 vaccine programme and follow the current lockdown restrictions whilst we do this – to protect the vulnerable until they are vaccinated.”


Prof Liam Smeeth, Professor of Clinical Epidemiology, London School of Hygiene and Tropical Medicine, said:

“These data are potentially concerning, but it is important to emphasise that these are laboratory findings, and it would be unwise to extrapolate to clinical effects in humans at this stage. The data do raise the possibility that the protection gained from past infection with Covid-19 may be lower for re-infection with the South African variant. The data also suggest that the existing vaccines could be less effective against the South African variant. However, before coming to those conclusions, we need large-scale studies over time among populations where the variant is common looking at re-infection risk and to assess vaccine effectiveness.”


Prof James Naismith, Director of the Rosalind Franklin Institute, and University of Oxford, said:

“The mutants in the SARS-CoV-2 501Y.V2 (sometimes referred to as the South African strain) are of concern to scientists. The study asks the following question, does the sera from people who have been infected and recovered from the original covid19 strain neutralise (kill) the new strain.  The answer is that around half the sera tested showed a much diminished response. The study is well done and I assume will make its way through peer review. It’s not good news but it’s not unexpected. It’s human nature to enjoy frightening ourselves, but we must not panic. The real world human immune response is more than serum based neutralisation (antibodies). Of course we would rather neutralisation had occurred but this does not mean that the new virus will infect, make ill and spread from those who have already been infected with the original strain. 

“What is true for immunity from infection is likely but not certain to be true for immunity from vaccination. The vaccines do stimulate very strong responses, immunity is a sliding scale it’s not an on off switch. 

“What can we do?

1. Focus on vaccinating people against the strains that are killing over 1000 people a day in the UK.

2. Socially distance, wear a mask and observe hand hygiene, less infections means less deaths.

3. We need more investment in science to monitor and characterise these new strains, understanding them before they hit will save lives.

4. We should continue to invest in finding front line medicines that can help lessen the seriousness of covid19 infection, this would dramatically reduce the harm of any future strain.

5. We should eradicate the virus across all age groups in the UK and in every country. The more virus circulates, the more risk of getting new strains. Helping poorer countries helps ourselves.

6. We should vaccinate as many people as possible. Today’s vaccines even if they turn out to be not completely protective against this or a future hypothetical new strain,  may still give enough response to make any new infection much much less serious.

“In a nutshell, it seems possible that any single vaccine may not end the story, but we know we can develop new altered vaccines quickly. We must not be despondent, we have the tools that allow us to understand and defeat this. However, it will take time and there may be some setbacks.”


Prof Lawrence Young, Virologist and Professor of Molecular Oncology, Warwick Medical School, said:

“A variant of the SARS-CoV-2 virus might partially evade immune protection or prior infection. This preprint suggests that individuals might be able to get infected with a variant of SARS-CoV-2 even if they have previously had COVID-19. It also shows we urgently need to find out if we could see infection with this variant post vaccination.

“This study from the National Institute for Communicable Diseases in South Africa shows that the South African virus variant (501Y.V2) is able to escape neutralisation by both monoclonal antibodies (including those being used therapeutically) and by convalescent plasma/sera from previously infected individuals. It is a very thorough study that examines the impact of specific mutations in the spike gene of 501Y.V2 and how these affect the binding of neutralising antibodies. High levels of resistance to convalescent plasma/sera where observed with nearly half (21 of 44, 48%) of the samples having no detectable neutralising activity. Similarities between the mutations in 501Y.V2 spike and the variant recently found in Brazil suggest that this Brazilian variant will also exhibit significant levels of neutralisation resistance. This study suggests that previously infected individuals may be susceptible to reinfection with virus variants – something which has already been reported in two cases in Brazil. It also has important implications for the effectiveness of current SARS-CoV-2 vaccines which are all based on the original spike gene.

“It is important that we now determine the neutralising ability of antibodies against virus variants generated in response to vaccination and study the immune response in individuals infected with virus variants.”



All our previous output on this subject can be seen at this weblink:



Declared interests

None received.

in this section

filter RoundUps by year

search by tag