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How vaccines can be ‘tweaked’ to combat new Covid variants

Spread of South Africa strain of coronavirus has intensified efforts to boost jab efficacy

England's deputy chief medical officer has urged Britons not to “panic” over suggestions that the Oxford-AstraZeneca jab offers only limited protection against the South African strain of coronavirus.

Professor Jonathan Van-Tam told a No. 10 press briefing yesterday that the variant was “not likely” to become the dominant strain in the UK, despite warnings from researchers that the South African version appears to be more contagious. “The stories and the headlines around variant viruses and vaccines are a bit scary - I wish they weren’t,” Van-Tam added.

However, with new Covid variants also identified in California, Brazil and the UK, attention is turning to how vaccines can be tweaked to combat mutations of the virus.

Pharmaceutical giants including Pfizer-BioNTech, Moderna and Oxford-AstraZeneca are all “looking at ways to improve their vaccines”, The Guardian reports.

Jabs that use mRNA technology, such as those developed by Pfizer-BioNTech and Moderna, are considered by experts to be easier to tweak than more traditional vaccines, such as the Oxford-AstraZeneca version.

“Blood drawn from people vaccinated with the Moderna Covid-19 vaccine had antibodies that blocked” the South Africa variant, The Verge says. But “it took around six times more of them to block this strain than the predominant form of the virus”, the site continues.

Experts are now aiming to “measure the antibody levels of people who were vaccinated but still got sick with Covid-19, and identify the cutoff where the vaccine wasn’t protective”.

The Gavi vaccine alliance says that tweaking the Pfizer-BioNTech and Moderna vaccines would involve “adjusting the code of the DNA template, which should be a relatively quick and simple process”.

Although the process has “no historical precedent”, owing to the newness of the technology involved, it “would probably involve modifying the vaccine adenovirus so it contains a slightly different piece of code matching the spike protein from the new coronavirus variant”.

In a note of optimism, Gavi adds that “the production of a new influenza vaccine each year demonstrates that it is possible to adapt existing vaccines to keep up with viral mutations”.

This confidence has been echoed by some Covid vaccine producers, including BioNTech, whose experts are estimating that they can make a tweaked jab within six weeks.

However, the Oxford-AstraZeneca team say a version of their jab that is able to better tackle the South African strain may not be ready until autumn.

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