Preliminary data from researchers at the University of Oxford indicates the ChAdOx1-nCov19 vaccine still effective at causing immunity against the Kent variant.
The B.1.1.7 variant was identified in Kent in late 2019. Mutations in the parts of the virus’ genetic code which determine the structure of the spike protein mean the variant is up to 70% more transmissible than previously circulating variants. This allowed it to become the dominant variant circulating in the United Kingdom. Cases of the variant in the United States are doubling every 10 days.
The vaccine, developed with AstraZeneca, uses an inert adenovirus to introduce a strand of genetic material from the SARS-CoV-2 virus to cause human cells to produce viral spike proteins. Complementary antibodies are produced by the immune system in response to spike proteins. These antibodies remain in the body where they can fight off future infections.
If the structure of the spike protein changes too much compared to previous variants, antibodies produced from vaccination or prior infection will not provide immunity or will be less effective. Mutations in the spike protein of the Kent variant help it attach more tightly onto human cells and replicate more easily, but also slightly alter its shape.
In a pre-print published in The Lancet, which is yet to undergo peer-review, the researchers found that the Oxford vaccine had a similar effectiveness against the Kent variant than previous variants. It was also shown to decrease the viral load in people who have been vaccinated, meaning they are less likely to infect others.
Sarah Gilbert, Chief Investigator on the Oxford vaccine trial, said “Coronaviruses are less prone to mutation than influenza viruses, 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.”
Image: Steven Cornfield via unsplash.com
