Oxford scientists believe they have made a breakthrough in their quest for a Covid-19 vaccine after discovering that the jab triggers a response that may offer a "double defence" against the virus.

Blood samples taken from a group of UK volunteers given a dose of the vaccine showed that it stimulated the body to produce both antibodies and ‘killer T-cells’, a senior source said.

The discovery is promising because separate studies have suggested that antibodies may fade away within months while T-cells can stay in circulation for years.

Another source close to the team described the presence of both antibodies and T-cells as a “double defence” against Covid-19.

AstraZeneca has signed a deal to produce up to two billion doses. If all goes well, the researchers hope the vaccine may be ready as early as OCT!

a study published in Nature today researchers found that T Cells from the SARS outbreak had lasted for 17 years.