From The Evening Standard:
Half of over-50s have had Covid booster jab... At least 6.1 million booster doses of Covid-19 vaccine have been delivered across the UK.
Half? Really? Clearly, there are about 30 million over-50s in the UK, so that's nowhere near half.
Some outlets read and understood the NHS press release, for example the North West Mail:
NHS delivers Covid booster to half of eligible people aged 50 and over
The key word here is "eligible" i.e. over-50s with underlying health issues, who care for elderly parents, NHS workers and so on.