The Government has pledged to work through age groups and give every adult an appointment by January.
The latest news has prompted some of the UK’s leading scientists and health officials to urge people to accept the offer when their turn comes.
Dr Mary Ramsay, head of immunisation at the UKHSA, said people should treat the early estimates “with caution” but added they suggest the risk of catching Omicron is “significantly reduced” with the booster.
She urged everyone to “take up their booster when eligible”, as it could provide “higher protection against the serious complications of COVID-19”.