AZ/Oxford University vaccine shows 82.4% efficacy with extended dosing schedule

Data from the phase 3 study that was conducted in the UK, Brazil and South Africa shows that administering the AZ/Oxford vaccine with a 12-week gap between the two doses increases the vaccine’s effectiveness.

The data was published in a preprint with The Lancet, which reported that ‘vaccine efficacy was higher, after the second dose, in those with a longer prime-boost interval, reaching 82.4% in those with a dosing interval of 12 weeks or more’.

In the study, 1,293 participants received two full doses of the vaccine 12 weeks apart.

These findings shed more light on the initial data that showed that a half dose, followed by a full dose was more effective, offering up to 90% protection from the virus. These results were reported after approximately 8,000 volunteers received a half dose and then a full dose in error.

AstraZeneca has also reported that the vaccine is 76% effective in protecting against the virus after the first dose. The company added that new data confirmed that its vaccine was 100% effective in preventing hospitalisations or severe illness ten days after people had received the first dose.

Importantly, for the first time, data released shows that the AZ/Oxford vaccine can reduce the likelihood of people catching and passing on the virus, which could significantly slow the spread of the virus.

The data, which has not yet been published or reviewed, showed the AZ/Oxford vaccine could cut transmission by up to 67%.

In response to the threats posed by the UK and South African variants that are currently being tracked in the UK, Professor Pollard from Oxford University said that his team is already working to update the vaccine to increase its efficacy against these mutations.

"I think the actual work on designing a new vaccine is very, very quick because it's essentially just switching out the genetic sequence for the spike protein,” said Professor Pollard.

"And then there's manufacturing to do and then a small scale study. So all of that can be completed in a very short period of time, and the autumn is really the timing for having new vaccines available for use," he added.

Sir Mene Pangalos, executive VP of biopharmaceuticals research and development at AstraZeneca, commented: "Our ambition is to be ready for the next round of immunisations that may be necessary as we go into next winter. That's what we're aiming for."