The Oxford adenoviral vaccine has had little success in preventing infection with the South African mutation of COVID-19, it has been announced raising new concerns about the virus’s ability to mutate to avoid vaccines.
The news led to efforts being stepped up to prevent transmission of the mutation in the UK.
Oxford University researchers said the impact of the vaccine in preventing infection with mild to moderate disease from the mutation was “minimal.”
It is still hoped it can prevent severe disease with the vaccine – and tests involving a similar adenoviral vaccine have suggested this to be the case.
Oxford said it is also working to adapt vaccines against the new strains of virus.
The UK has had a small number of cases of the South African variant – but the discovery led to South Africa suspending use of the Oxford vaccine.
The research in South Africa involved 2,000 volunteers with an average age of 31. South Africa was involved in trials of the vaccine, raising questions about whether early expose helped the emergence of the mutation.
Researcher Professor Shabir Madhi, from Witwatersrand, 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.
“These findings recalibrate thinking about how to approach the pandemic virus and shift the focus from the goal of herd immunity against transmission to the protection of all at risk individuals in population against severe disease.”
Oxford researcher Professor Andrew Pollard 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 using a similar viral vector, vaccines may continue to ease the toll on health care systems by preventing severe disease.”
Fellow researcher Professor Sarah Gilbert said: “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.”
Over the weekend the Department of Health announced additional areas to be targeted for “surge testing” to prevent transmission of the new variants. The latest districts are in Worcestershire, Sefton, Bristol and South Gloucestershire.
* A study by Cambridge University has highlighted how chronic infection can lead to the development of new SARS-CoV-2 mutations.
Reporting in Nature, the researchers show how the virus mutated in an immunocompromised patient treated with convalescent plasma.
The mutation that developed was similar to the B1.1.7 Kent variant, doubling its infectivity, they found.
The patient was being treated for marginal B cell lymphoma and was under treatment for COVID-19 for nearly three months. After initial antiviral treatment, his condition appeared to stabilise – but then it deteriorated and he died.
Researcher Professor Ravi Gupta said: “What we were seeing was essentially a competition between different variants of the virus, and we think it was driven by the convalescent plasma therapy.
“The virus that eventually won out – which had the D796H mutation and ?H69/?V70 deletions – initially gained the upper hand during convalescent plasma therapy before being overtaken by other strains, but re-emerged when the therapy was resumed. One of the mutations is in the new UK variant, though there is no suggestion that our patient was where they first arose.”
He added: “Given that both vaccines and therapeutics are aimed at the spike protein, which we saw mutate in our patient, our study raises the worrying possibility that the virus could mutate to outwit our vaccines.
“This effect is unlikely to occur in patients with functioning immune systems, where viral diversity is likely to be lower due to better immune control. But it highlights the care we need to take when treating immunocompromised patients, where prolonged viral replication can occur, giving greater opportunity for the virus to mutate.”
Kemp, SA et al. SARS-CoV-2 evolution during treatment of chronic infection. Nature 5 February 2021; doi: 10.1038/s41586-021-03291-y
Leave a Reply