Two-thirds of Brits aged 16 to 24 now have Covid antibodies, according to official blood-testing data.
Government statisticians estimate around 67 per cent of the youngest adults and oldest teenagers in England now have the virus-fighting proteins.
The proportion is even higher in Wales (71 per cent) and Northern Ireland (68.9 per cent) but lower in Scotland (57.3 per cent).
This is despite nearly half of the age group having yet to be vaccinated, with rates lagging behind among the young.
It suggests immunity has also been picked up through natural infection, with the third wave being driven by the rampant spread of the virus among teens and people in their 20s.
Experts said vaccine uptake among the young is good but there is still 'some way to go' amid fears the rollout may be stumbling to a halt.
Two thirds of Brits aged 16 to 24 now have Covid antibodies, official data has shown despite nearly half not having had a jab
Antibodies were highest in the East Midlands, where 91.7 per cent of all adults tested positive for the proteins
The third wave being driven by the rampant spread of the virus among teens and people in their 20s, with people aged 20 to 24 having the highest infection rate in England (1,133 per 100,000 on July 15)
This graph shows the number of people who are yet to be vaccinated against Covid in every age group. It shows there are more than 1.7million 18 - 24 year olds still to get the jab, followed by more than a million 25 to 29-year-olds
The ONS — which analyses tens of thousands of blood samples every fortnight — doesn't break down whether antibodies came from jabs or infection.
Their presence generally means a person has at least some protection against the disease and won't fall ill.