The number of cases of the Delta variant of covid first detected in India has increased by 240 per cent in the UK in the last week.
Public Health England today said the number of cases had risen from 12,431 to 42,323 in the latest seven-day period, an increase of 29,892 cases.
This could put further pressure on the Government to delay the final easing of lockdown on June 21 – though the majority of cases appeared to be in unvaccinated people.
Nick Thomas-Symonds, Labour’s shadow Home Secretary, said: “These figures are terrible. The pace at which cases of the Delta variant continue to rise is deeply worrying and is putting the lifting of restrictions at risk.
“The blame for this lies with the Prime Minister and his reckless refusal to act on Labour’s repeated warnings to secure our borders against Covid and its variants.”
The Delta variant has caused 42 deaths – 23 in unvaccinated people, seven in people who have had one dose and 12 in people who have had two doses, though many of the latter group are believed to have had underlying health conditions.
However the mortality rate is only currently 0.1 per cent – well below the Kent variant – and only about 2.5 per cent of people with the variant need to go to A&E.
Part of the increase in case numbers is because faster “genotype” testing is being used, which delivers results within 48 hours rather than about a week for genome sequencing.
The latest figures, which cover the period to Wednesday, come after a 79 per cent increase in the detection of the variant in the previous week.
PHE’s weekly variants report said the Delta variant now accounts for 90 per cent of all UK cases of covid. The variant continues to spread at a “significantly higher rate” than the Alpha or Kent variant previously dominant in the UK.
PHE said the mortality rate for the Delta variant appeared to be 0.1 per cent, compared with 1.9 per cent for the Alpha/Kent variant. However it said that many of the patients with Delta had not had the virus for 28 days and there was a delay in reporting deaths.
It said that of 33,201 Delta cases identified since February 1, at least 851 – a total of 2.5 per cent - required a visit to A&E, of which at least 223 required an overnight stay in hospital. This
The “secondary attack rate” – the rate at which an infected person spreads the virus – is higher for Delta in traveller and non-traveller cases and among household and non-household contacts. The risk of Delta spreading within households is said to be 60 per cent higher than for Alpha.
In addition, early data from both England and Scotland “demonstrate an increased risk of hospitalisation with Delta compared to Alpha”, PHE said.
Growth rates for Delta cases are high across the regions, with regional estimates for doubling time ranging from 4.5 days to 11.5 days
PHE said the data currently suggests that the vaccination programme continues to mitigate the impact of this variant in populations where large numbers have had two jabs.
Dr Jenny Harries, chief executive of the UK Health Security Agency, said: “With numbers of Delta variant cases on the rise across the country, vaccination is our best defence. Remember that two doses provide significantly more protection than a single dose.
“However, while vaccination reduces the risk of severe disease, it does not eliminate it. 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. 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.”