Britain’s new Covid vaccine has yielded good results in initial laboratory tests.
It could be used to create a vaccine to protect people against multiple virus variants.
The government said in February it could order 50 million doses of the multivalent jab.
It is hoped that human trials will take place later this year.
Britain is currently vaccinating people under 40 using mRNA vaccines which are made abroad, such as Pfizer in Belgium.
In June, a first version of the GSK jab was found to be just 48 per cent effective in preventing Covid during early trials.
However, scientists found the new vaccine to be “strongly improved” in protecting against the virus offering a stronger immune response with higher levels of antibodies.
The most recent trials involved macaque monkeys which were given either the original vaccine or a new version known as CV2CoV.
The companies said on Monday a blood analysis of the animals showed the next-generation vaccine triggered virus-fighting antibodies.
It also triggered immune cells targeting infected cells faster and in greater quantities than CureVac’s first-generation vaccine candidate.
Higher antibody blood counts were observed across virus variants of concern including the Beta, Delta and Lambda lineages.