No fully-vaccinated under-50 has died from the delta variant, even though younger age groups make up 90 per cent of cases, a new report from Public Health England (PHE) has shown.

For the first time, PHE has broken down cases, admissions and deaths into over-50s and under-50s for the variant.

The divide shows vaccine effectiveness more clearly because older age groups are far more likely to die than younger people, making it trickier to tease out the benefit when the figures are rolled together.

The latest technical briefing records 92,029 delta cases sequenced since February 1, with 82,458 in the under-50s and 9,571 occurring in the over-50s.

As of June 21, there have been 117 deaths in England of people who were confirmed as having the delta variant and who died within 28 days of a positive test.

The figures show only eight deaths occurred in the under-50s, and none in those who had been fully vaccinated, with six occurring in people who had not been vaccinated at all.

More than three quarters – 78 per cent – of admissions in the under-50s were among unvaccinated people, and just three per cent were fully vaccinated. 

Of the 109 deaths which occurred in the over-50s, 50 had been fully vaccinated, but experts said that the vast majority of the over-50s had now had two jabs, so the numbers of older fully vaccinated people dying was expected to rise. 

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Meaghan Kall, an epidemiologist at PHE, said: “For people who are fully vaxxed but have ‘breakthrough infections’ and go on to be hospitalised, it is very likely that there’s a link to why vaccine wasn’t effective and the fact they had severe disease, such as old age or a health condition that affects the immune system.

“A priority is to investigate the characteristics of people who are hospitalised and die post-vaccination, to understand reasons and also tell if delta is a more severe or different clinical disease.”

The report showed that, as of June 21, a total of 1,320 people have now been admitted to hospital in England with the delta variant – a rise of 514 on the previous week.

Some 902 of the 1,320 people were under the age of 50 while 418 were over 50.

Figures show the death rate for the delta variant is still very low, at 0.3 per cent, compared to the 1.9 per cent for the alpha variant. However, most cases have occurred within the past 28 days and there will be a lag before admissions translate into deaths. 

Taking just delta cases which occurred more than 28 days ago, the death rate rises to 0.9 per cent for the variant, suggesting that there are around 640 deaths already baked into the system which are likely to occur within the next month.

However the number of people with immunity against the virus is continuing to rise, with all over-18s now invited for their jab.

Latest figures show that 82 per cent of the adult population have had at least one jab and 60 per cent have been fully vaccinated, with Office for National Statistics (ONS) figures showing eight in 10 people over the age of 16 now have antibodies to Covid. 

Although latest data show the number of people in England with Covid has risen in a week from one in 520 to one in 440, experts said that it appeared that the vaccines were winning the race against the variant.

Professor James Naismith, the director of the Rosalind Franklin Institute, and of the University of Oxford, said: “The rate of increase in delta is thankfully moderate and it would suggest that current restrictions will give time to allow the vaccination campaign to do its work. 

“If we can all keep to the current restrictions for a bit longer, we will defeat the delta variant in the UK. Vaccination has reduced the hospitalisation and burden on the NHS. 

“Whilst the UK is not out of the woods yet, it appears that we will win the race against delta (just).”

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PHE also said that a further mutated virus, named Lambda (C.37) has been designated as a Variant Under Investigation after six cases were found in Britain.

The variant has been linked to a surge in cases in South America, and there are concerns it may be more transmissible and evade immunity. 

PHE said there is currently no evidence that this variant causes more severe disease or renders the vaccines currently deployed any less effective.