A small trial of just 2,026 people in South Africa found the jab had 'limited efficacy' in protecting against mild and moderate disease caused by the mutant strain, which has been found in 11 people in the UK who have not recently travelled from abroad.
However nobody died or was hopitalised during the study by South Africa's University of the Witwatersrand and Oxford University, which has not yet been published but has been seen by the Financial Times.
The pharmaceutical giant said scientists have already begun adapting the vaccine to kill the new variant, with hopes a booster shot will be ready by autumn if required.
AstraZeneca said it remains confident that its vaccine can prevent severe disease caused by the variant- and pointed out that the trial could not measure its effectiveness at preventing severe disease caused by the mutant strain because the median age of participants was 31.
"We do believe our vaccine could protect against severe disease, as neutralising antibody activity is equivalent to that of other Covid-19 vaccines that have demonstrated activity against more severe disease, particularly when the dosing interval is optimised to 8 to 12 weeks," an AstraZeneca spokesman said.
Earlier, the European Commission gave approval for the use of the Covid-19 vaccine developed by AstraZeneca, the final step to allowing Europe to use it across the Union.
AstraZeneca is to cut deliveries of its Covid-19 vaccine to the EU by 60% in the first quarter of the year due to production problems.
As we reported, due to vaccine supply delays, the European Union has stepped up pressure on the British-Swedish pharmaceutical company AstraZeneca. EU states are considering suing AstraZeneca for breach of contract.