UK starts mix-and-match Covid-19 vaccine trial to assess immune response

Britain has launched a trial to assess the immune responses generated if doses of the vaccines from Pfizer and AstraZeneca are combined in a two-shot schedule.

The British researchers behind the trial said data on vaccinating people with the two different types of vaccines could help with understanding of whether shots can be rolled out with greater flexibility around the world. Initial data on immune responses is expected to be generated around June.

The trial will examine the immune responses of an initial dose of Pfizer vaccine followed by a booster of AstraZeneca's, as well as vice versa, with intervals of four and 12 weeks.

Both the mRNA shot developed by Pfizer and BioNtech and the adenovirus viral vector vaccine developed by Oxford University and AstraZeneca are currently being rolled out in Britain, with a 12-week gap between two doses of the same vaccine.

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Race to improve vaccines

Thousands of variants have been documented as the virus mutates, including the so-called British, South African and Brazilian variants which appear to spread more swiftly than others.

British Vaccine Deployment Minister Nadhim Zahawi said it was very unlikely that the current vaccines would not work against the new variants.

"Its very unlikely that the current vaccine won't be effective on the variants whether in Kent or other variants especially when it comes to severe illness and hospitalisation," Zahawi told Sky News.

"All manufacturers, Pfizer-BioNTech, Moderna, Oxford-AstraZeneca and others, are looking at how they can improve their vaccine to make sure that we are ready for any variant, there are about 4,000 variants around the world of Covid now."

While thousands of variants have arisen as the virus mutates on replication, only a very small minority are likely to be important and to change the virus in an appreciable way, according to the British Medical Journal.

The so called British variant, known as VUI-202012/01, has mutations including a change in the spike protein that viruses use to bind to the human ACE2 receptor - meaning that it is probably easier to catch.

"We have the largest genome sequencing industry, we have about 50 percent of the world's genome sequencing industry, and we are keeping a library of all the variants so that we are ready to respond, whether in the autumn or beyond, to any challenge that the virus may present and produce the next vaccine," Zahawi said.

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GSK, CureVac cooperation

British pharmaceutical group GlaxoSmithKline and German biotech firm CureVac on Wednesday announced plans to jointly develop a coronavirus vaccine with the potential to counter multi-variants of Covid-19.

"The development programme will begin immediately, with the target of introducing the vaccine in 2022, subject to regulatory approval," a joint statement said.

GSK will also support the manufacture this year of up to 100 million doses of CureVac's first generation Covid-19 vaccine, it added.

The collaboration, building on an existing relationship, is to develop next generation Covid-19 vaccines "with the potential for a multi-valent approach to address multiple emerging variants in one vaccine".

The pair noted that "the increase in emerging variants with the potential to reduce the efficacy of first generation Covid-19 vaccines requires acceleration of efforts to develop vaccines against new variants to keep one step ahead of the pandemic".

GSK chief executive Emma Walmsley said "next generation vaccines will be crucial in the continued fight against Covid-19".

The value of the new collaboration was put at 150 million euros ($181 mill ion).

"We are very pleased to build on our existing relationship with GSK with a new agreement," said CureVac chief executive Franz-Werner Haas.

"With the help of GSK's proven vaccine expertise, we are equipping ourselves to tackle future health challenges with novel vaccines."

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