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 accounting for 99% of Covid cases. On Friday 10,476 Covid cases and 11 deaths within 28 days of a positive test were reported in the UK – the former a slight decline compared with the 11,007 new cases reported the day before. According to the government’s Scientific Advisory Group for Emergencies (Sage), the latest R number for England is between 1.2 and 1.4, with the number of new Covid infections growing by 3% to 6% a day – in the north-west the growth is even higher at 5% to 8% a day. The group cautions that lags in data mean the figures represent the spread of Covid about two to three weeks ago. According to Public Health England data based on whole-genome sequencing and a more rapid approach known as genotyping, 99% of Covid cases in the UK involve the Delta variant. The Delta variant, also known as B.1.617.2, combined with relaxations in coronavirus restrictions, is believed to be behind the 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 PHE Public Health England (PHE) reveal cases of the variant have risen by 33,630 since last week, with another report from PHE supporting previous evidence that Delta is more transmissible than the Alpha variant, B.1.1.7. The report also adds to evidence the Delta variant is somewhat more resistant to Covid vaccines, particularly after just one dose – although protection is higher against hospitalisation than symptomatic disease. Considering the different Covid jabs together, the report suggests one dose offers 75% protection against hospital admissions for Delta while two doses provide 94% protection – although 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 a greater risk of hospitalisation. Nonetheless, Prof Rowland Kao, of the University of Edinburgh, who contributes to the Spi-M modelling subgroup of Sage, said a rise in hospitalisations was expected. “While the vaccines seem to work better against severe infection causing hospitalisation, we would expect to see more hospitalisations [with Delta] overall compared to if we only had the Alpha variant to contend with simply because [of] its greater transmissibility,” he said. According to the PHE report, from 1 February to 14 June 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, only 7.7% of the 53,163 Delta infections in the same period among those with known vaccination status occurred in people who had received both Covid jabs at least 14 days before, compared with 66.8% in unvaccinated people. Meaghan Kall, an epidemiologist at PHE, tweeted it was important to understand “whether Delta infection leads to more serious disease, and who are the people that do worse with Delta, what are their characteristics?” According to PHE data based on whole-genome sequencing and a more rapid approach known as genotyping, 99% of Covid cases in the UK involved the Delta variant. While educational settings have recently been the most common settings for reported exposures, in the latest week the proportion linked to schools declined while that linked to hospitality settings and travel rose considerably. Kao said if indications cases were slowing down in many areas are real it was most likely down to the combination of natural immunity and vaccinations as well as the impact of half-term. “This also in part likely explains the fact that hospitality seems more important – the reduction of the effect of schools means that other factors by comparison will have a greater impact and also there is likely to be more mixing in hospitality locations while people are on holiday,” he said, adding it would become clear if the drop was a temporary decline in the coming weeks. Further analysis by PHE suggests doubling times of Delta vary around the country, from 3.5 days in Yorkshire and the Humber to 16 days in the east of England – although there is uncertainty around some of these estimates. The PHE findings chime with the latest survey data from the Office for National Statistics based on swabs collected from randomly selected households, which shows an estimated one in 520 people in the community in England are thought to have had Covid in the week ending 12 June, up from about one in 560 people the week before. Dr Jenny Harries, the chief executive of the UK Health Security Agency, said Covid 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,” she said. “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.”