Delta variant causes more than 90% of new Covid cases in UK

Variant first discovered in India is thought to spread more easily and be more resistant to vaccines

More than 90% of Covid cases in the UK are now down to the coronavirus Delta variant first discovered in India, data has revealed, as the total number of confirmed cases passed 42,000.

Also known as B.1.617.2, the Delta variant has been linked to a rise in Covid cases in the UK in the past weeks. It is believed to spread more easily than the Alpha variant, B.1.1.7, that was first detected in Kent, and is somewhat more resistant to Covid vaccines, particularly after just one dose. It may be also associated with a greater risk of hospitalisation.

Now, Public Health England (PHE) has said that more than 90% of new Covid cases in the UK involve the Delta variant. Indeed the most recent data suggests the figure could be as high as 96% of new cases in England.

The PHE report further revealed that cases of the virus are doubling between every 4.5 and 11.5 days, depending on the region of England, and that it has about a 60% increased risk of household transmission compared with the Alpha variant. Confirmed cases in the UK to date have risen by 29,892 to 42,323.

The steep jump in cases is, in part, down to the use of a new technique to determine the variant present in a positive Covid sample. Previously, positive samples were sent to laboratories for whole-genome sequencing – a process that took five to 10 days to return results.


However, the new data includes results from a more rapid approach known as genotyping in which, rather than looking at the whole genome of the virus to work out which variant is involved, only key sections of the genome are examined. This gives results within 48 hours, with the report revealing it is highly accurate when it comes to picking up the Delta variant.

Using this approach, together with the more time-consuming genome-sequencing technique, the team says the most recent data shows 96% of Covid cases in England involve the Delta variant.

Dr Jenny Harries, the chief executive of the UK Health Security Agency, urged people eligible for vaccination to come forward to receive the jab.

“With numbers of Delta variant cases on the rise across the country, vaccination is our best defence,” she said, noting two doses provided significantly more protection than a single dose. “However, while vaccination reduces the risk of severe disease, it does not eliminate it,” she added.

That is backed up by the data. According to the report, since the start of February to 7 June, there were 33,206 Delta cases in England: while 19,573 were in unvaccinated individuals, 1,785 were among fully vaccinated people and 7,559 were among those who had received one jab, with the vaccination status of the remainder unclear.

In total, 383 people in England were admitted to hospital with the Delta variant over that period – 223 of whom tested positive for Covid before turning up at A&E – with 42 having had two doses of the jab, 86 having one dose and 251 unvaccinated.

Of the 42 deaths recorded in England within 28 days of a positive test involving the Delta variant, 23 were in unvaccinated people, with 12 among those who were fully vaccinated and seven among people who had had one dose.

The report chimes with survey data from the Office for National Statistics based on swabs collected from randomly selected households, which shows Covid infection levels are increasing in Britain.

According to the latest estimates, about 96,800 people in the community in England had Covid in the week ending 5 June – equating to about 1 in 560 people – compared with 85,600 people, or about one in 640, the week before. Rises were also seen in Scotland and Wales, while the trend was unclear for Northern Ireland.

deaths UK

Again, the picture varies by region – although the low number of people testing positive means the figures have a higher degree of uncertainty.

“In the week ending 5 June 2021, the percentage of people testing positive has increased in the north-west, West Midlands, London and the south-east,” the report said, although it added there were early signs of a decrease in the percentage of people testing positive in the east of England.

There are also differences by age, with infection levels rising in younger adults up to 34 years old, and those aged 50 to 69 years old. As with the PHE report, the ONS data suggests the Delta variant is now dominant in England.

Further data from the ONS suggests people in Great Britain are becoming less concerned about keeping their distance from each other. According to the latest figures, the proportion of adults maintaining social distancing with people outside their household fell to 68% over the period 2-6 June compared with 74% the week before, while – as per last week – 50% of adults said they had met up indoors with someone not in their household, childcare or support bubble in the past seven days.

In addition, 12% of adults said they planned to go on a trip abroad before September, with 71% saying the trip would be a holiday. The use of face coverings outside of the home has remained high at 96% in the most recent week.

“With data showing that Delta is significantly more transmissible than Alpha, it is just as important as ever to follow public health advice, which has not changed,” said Harries. “Get vaccinated, work from home where you can and remember ‘hands, face, space, fresh air’ at all times. These measures work, and they save lives.”


Nicola Davis Science correspondent

The GuardianTramp

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