The total number of cases of the Covid Delta variant in the UK has risen to 75,953 to date, data has revealed, with the variant now accounting for 99% of Covid cases.
Also known as B.1.617.2, the Delta variant, combined with relaxations in coronavirus restrictions, is believed to be behind a sharp rise in Covid cases in the UK in the past weeks – a development that led Boris Johnson to delay the planned 21 June date for full lifting of Covid restrictions in England.
The latest figures from Public Health England (PHE) reveal that cases of the variant have risen by 33,630 since last week, with data supporting previous reports that Delta is more transmissible than the Alpha variant, B.1.1.7. Another report from PHE adds to evidence the Delta variant is somewhat more resistant to Covid vaccines, particularly after just one dose – although protection is far higher against hospitalisation that symptomatic disease.
Considering the different Covid jabs together, the team say one dose offers 75% protection against hospitalisation for Delta compared with 78% for Alpha, while two doses provide 94% protection against hospitalisation for Delta compared with 92% against Alpha – although it is important to note these vaccine effectiveness figures are estimates that lie within a range of possible values.
The findings are important, not least because data suggests the Delta variant may be associated with around a twofold greater risk of hospitalisation, a link seen in data from both England and Scotland.
According to the PHE report, there have been 806 hospital admissions involving the Delta variant from 1 February to 14 June – 488 of which had tested positive for Covid before arriving at A&E. Of these 806, 527 were unvaccinated individuals while 84 had received both doses of a Covid jab at least 14 days before.
Over the same period, there have been 73 deaths with the Delta variant, 34 of which were among unvaccinated individuals, 11 of which were among those who had received one dose of a Covid vaccine and 26 of which occurred in people who had received both doses of a Covid jab. The vaccination status of the remainder was unknown. However the report reveals that only about 7% of the 60,624 Delta infections from 1 February to 14 June occurred in people who had received both Covid jabs at least 14 days before, compared with 59% in unvaccinated people.
The PHE report also sheds light on the spread of the Delta variant. According to data based on whole-genome sequencing and a more rapid approach known as genotyping, 99% of Covid cases in the UK now involved the Delta variant.
As before, educational settings and workplaces were found to be the most common settings for reported exposures, however in the latest week hospitality settings and travel have accounted for a larger proportion.
Further analysis, based on samples that test positive for what is known as the “S gene” – the vast majority of which involve the Delta variant – shows that doubling times vary around the country.
According to this approach, doubling times for Delta cases are just 3.5 days in Yorkshire and the Humber, about six days in the north-west of Englang and the West Midlands, and about eight to 10 days in London, the east Midlands, and south-east, while the east of England had the longest doubling time of 16 days – although there is uncertainty around some of these estimates.
The approach also shows that doubling times for Delta cases are fastest among younger people, at around a week for those aged under 34.
Dr Jenny Harries, chief executive of the UK Health Security Agency, said cases were rising rapidly across the country.
“The increase is primarily in younger age groups, a large proportion of which were unvaccinated but are now being invited to receive the vaccine. It is encouraging to see that hospitalisations and deaths are not rising at the same rate but we will continue to monitor it closely. The vaccination programme and the care that we are all taking to follow the guidance are continuing to save lives,” she said.
“Please make sure that you come forward to receive both doses of the vaccine as soon as you are eligible. Don’t drop your guard- practice ‘hands, face, space, fresh air’ at all times.”