At least 6.1 million booster doses of Covid-19 vaccine have been delivered in the UK, new figures show.
In Wales 322,591 booster doses had been delivered as of October 21 – the latest figure available.
It means at least one in eight people in the UK who have received a first and second dose of vaccine are likely to have also received a booster.
The figure for England includes a small number of third primary doses of vaccine, NHS England said.
Wales continues to lead the other nations in the proportion of double-jabbed people who have also received a booster, at 14.4%, according to analysis by the PA news agency.
This is despite the data for Wales running several days behind the other three nations.
The latest figure for England is 13.7%, with 13.1% for Scotland and 4.1% for Northern Ireland.
A breakdown by age group suggests nearly six in 10 double-jabbed people aged 80 and over in England have now had a booster (58%), along with nearly half of eligible 75 to 79-year-olds (47%).
The equivalent figures for Wales, as of the end of last week, were 47% and 31%.
Data on booster take-up among age groups in Scotland and Northern Ireland is not yet available.
In north-west England, north-east England and Yorkshire, 15.0% of all double-jabbed people are estimated to have received a booster – the highest proportion for any of the regions in England.
London has the lowest proportion, at 12.1%.