Latest estimates for the percentage of 18 to 39-year-olds who are unjabbed range from 21 per cent in Scotland to 25 per cent in Northern Ireland, with 22 per cent in England and 23 per cent in Wales.
In total, 4.2 million adults under 40 have yet to have their first dose, according to figures for vaccinations delivered up to yesterday (September 15). This includes nearly 2.7 million people aged 18 to 29.
First doses of Covid-19 vaccine have been available for everyone aged 18 and over since the end of June.
The figures suggest there is still a large minority of young adults reluctant to have the vaccine, despite a host of initiatives to encourage take-up, including publicity campaigns, pop-up vaccination centres and discounts from businesses.
Among 18 to 29-year-olds, the percentage of people unjabbed is as high as 27 per cent in England and Northern Ireland, with 24 per cent in Scotland and 23 per cent in Wales.
Across the UK as a whole, there are nearly 5.9 million people who are eligible for a jab but who have yet to receive any vaccine.
Of this total, about five million are in England, 402,000 in Scotland, 237,000 in Wales and 198,000 in Northern Ireland.
Large cities in England continue to be areas with particularly high levels of unvaccinated young adults.
Birmingham has the highest estimated percentage of unjabbed 18 to 29-year-olds (50.3 per cent), according to analysis by the PA news agency.
The next highest is Coventry (48.8 per cent), followed by the London borough of Islington (45.8 per cent), Liverpool (45.7 per cent) and Nottingham (44.0 per cent).
In total, there are 45 local authority areas in England where at least one third of 18-29 year-olds have yet to receive any vaccine.
These also include Manchester (42.7 per cent), Leicester (40.7 per cent), Sheffield (38.3 per cent) and Leeds (37.8 per cent).
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