Although the early data is positive for the company, AstraZeneca said on Tuesday it was working with its partner Oxford University to produce a vaccine tailored for Omicron, joining similar efforts from other vaccine-makers.

The Oxford study analysed blood samples from those infected with COVID-19, those vaccinated with two doses and a booster, and those previously infected with other variants of concern. It included samples from 41 people given three doses of Vaxzevria.

Scientists and governments are scrambling to bolster defences against Omicron with shots and therapies, as the variant threatens to become dominant globally and has prompted renewed curbs ahead of the holidays to contain infections.