Covid-19: AstraZeneca vaccine provides minimal protection against 501Y.V2 variant - new study

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  • South Africa received one million doses of the Oxford/AstraZeneca vaccine last week. 
  • A new study finds the vaccine provides minimal protection against the Covid-19 variant first identified locally in November.
  • Oxford University is working on a second generation of the vaccine that can target the mutated virus. 

The Oxford/AstraZeneca vaccine that South Africa received last week might not be effective against the more common 501Y.V2 variant that is spreading locally and globally.

A new pre-print and not yet peer reviewed paper by researchers from South Africa and the UK found that the two-dose Oxford/AstraZeneca vaccine "provides minimal protection against mild-moderate Covid-19 infection" in the 501Y.V2 variant. 

The study didn't assess the efficacy of the vaccine against severe infection of the coronavirus. 

Last week, the country received its first doses of the vaccine from the Serum Institute of India which are set to be administered to healthcare workers starting next week. 

In the latest study, researchers compared the strength of the vaccine against the original strain of Covid-19 and the new variant in about 2 000 local volunteers.

The vaccine worked effectively in the original Covid-19 strain, but showed only minimal protection against the 501Y.V2 variant.   

The 501Y.V2 variant was first identified by local researchers in November. Since then, the variant has been identified in other parts of the world. 

READ | Coronavirus: How the 501Y.V2 variant was able to quickly dominate infections 

"These early data, which will be submitted for scientific peer-review, appear to confirm the theoretical observation that mutations in the virus seen in South Africa will allow ongoing transmission of the virus in vaccinated populations, as has been recently reported in those with prior infection," the researchers said.  

Shabir Madhi, Professor of Vaccinology and Director of the Vaccines & Infectious Diseases Analytics Research Unit at University of the Witwatersrand, and chief investigator on the trial in South Africa said: "Recent data from a study in South Africa sponsored by Janssen which assessed moderate to severe disease, rather than mild disease, using a similar viral vector, indicated that protection against these important disease endpoints was preserved. 

This could be relevant to the ChAdOx1 nCoV-19 [AstraZeneca] vaccine, which has been developed using similar technology as the Janssen vaccine, and for which vaccine induced immune responses are also similar. These findings also force us to recalibrate thinking about how to approach the pandemic virus and shift the focus from the aspirational goal of herd immunity against transmission to the protection of all at risk individuals in the population against severe disease.

Andrew Pollard, Professor of Paediatric Infection and Immunity, and chief investigator on the Oxford vaccine trial, said: "This study confirms that the pandemic coronavirus will find ways to continue to spread in vaccinated populations, as expected, but, taken with the promising results from other studies in South Africa, such as those using a similar viral vector, vaccines may continue to ease the toll on healthcare systems by preventing severe disease."

'Calling it the SA variant is a stigmatising approach' - Prof Salim Abdool Karim on 501Y.V2

Second generation vaccines being developed

The University of Oxford is currently working to produce a second generation of the vaccine which has been adapted to target variants of the coronavirus with mutations.

Sarah Gilbert, Professor of Vaccinology at the University of Oxford said: "Efforts are underway to develop a new generation of vaccines that will allow protection to be redirected to emerging variants as booster jabs, if it turns out that it is necessary to do so. We are working with AstraZeneca to optimise the pipeline required for a strain change should one become necessary. This is the same issue that is faced by all of the vaccine developers, and we will continue to monitor the emergence of new variants that arise in readiness for a future strain change."


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