Video report by ITV News Science Editor Tom Clarke
The Oxford University researchers who developed the vaccine say it has a similar efficacy against the so-called Kent variant, compared with the original strain of Covid-19.
Experts had been concerned about whether or not the vaccines currently being rolled out throughout the UK would be effective against the strain that emerged after trials had been conducted.
The preprint also describes analysis which suggests vaccination with the Oxford/AstraZeneca jab results in a reduction in the duration of shedding and viral load, which may translate into a reduced transmission of the disease.
The emergence of the mutation, first detected in Kent and the south-east of the England, was partially blamed for the rapid spread of the virus, and increase in cases, before lockdown was imposed across the country in January.
Andrew Pollard, professor of paediatric infection and immunity, and chief investigator on the Oxford vaccine trial, said: “Data from our trials of the ChAdOx1 vaccine in the United Kingdom indicate that the vaccine not only protects against the original pandemic virus, but also protects against the novel variant, B117, which caused the surge in disease from the end of 2020 across the UK.”
Sarah Gilbert, professor of vaccinology, and chief Investigator on the Oxford vaccine trial, said: “All viruses accumulate mutations over time, and for influenza vaccines there is a well-known process of global viral surveillance, and selection of strains for an annual update of the vaccines.”
Between October 1 last year and January 14 this year, researchers used swabs taken from volunteers with both symptomatic and asymptomatic infection enrolled in a phase two or three vaccine efficacy study.
They looked at the data to work out which strain of the virus the participants had been infected with after receiving either the vaccine or the control.
According to the scientists, the protection against symptomatic infection was similar despite lower neutralising antibody titres (a measurement of how much antibody has been produced) in vaccinated individuals against the new UK variant (B117) than the non-B117 strain.
The study, which has not been peer-reviewed, reports that vaccine efficacy against symptomatic positive infection was similar for B117 and non-B117 lineages, at 74.6% and 84% respectively.
These are the first findings regarding the efficacy of the Oxford/AstraZeneca vaccine against new variants.
The Oxford team said researchers in South Africa were still looking at how effective the Oxford/AstraZeneca vaccine is against the strain first detected in that country, which has also been identified in the UK.
Public Health England (PHE) is investigating strains of coronavirus in the UK which have developed the same mutation.
Mene Pangalos, executive vice president of biopharmaceuticals research and development at AstraZeneca, said it would not be surprising to see reduced efficacy against this variant.
He explained: “I think it’s reasonable to say that what we know from other vaccines is, we’re not going to be surprised to see reduced efficacy, because we’ve seen from the J&J vaccines and from the Novavax vaccines that these variants do impact – at least in mild and moderate disease or mild disease – efficacy.
Researchers are already looking at ways to modify the existing vaccines quickly and simply, to protect against new variants.
Professor Gilbert said that coronaviruses are less prone to mutation than influenza viruses.
She added: “But we have always expected that as the pandemic continues, new variants will begin to become dominant amongst the viruses that are circulating and that eventually a new version of the vaccine, with an updated spike protein, would be required to maintain vaccine efficacy at the highest level possible.
“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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