Covid data heading in ‘negative direction’ as Delta variant doubles every nine days, says Ferguson

‘The data is pointing this week in a more negative direction than it was last week’ says top epidemiologist

Celine Wadhera
Friday 04 June 2021 10:54 BST
Professor Neil Ferguson
Professor Neil Ferguson (Thomas Angus/Imperial College London)

The Delta variant of Covid-19 is about 60 per cent more transmissible than previously-dominant mutations, Professor Neil Ferguson said on Friday, as he warned that overall UK data on the spread of the virus was heading in a “negative direction.”

The Imperial College London epidemiologist, responsible for coronavirus modelling used by the government, said the Delta variant, previously known as the Indian variant, was also up to twice as likely to result in hospitalisation for those unvaccinated, based on early data.

Asked about how infectious the new variant was, he told BBC Radio 4’s Today programme: “There’s some uncertainty around that, depending on assumptions and how you analyse the data. Between about 30 and maybe even up to 100 per cent more transmissible.” he said.

The Delta variant, first identified in India, has now become the dominant variant across most the UK. Although vaccination provides a good deal of protection, Professor Ferguson said that the Delta variant partially escapes vaccine immunity and may cause more severe disease.

That being said, he added that most hospitalisations associated with any coronavirus variant were among people who were unvaccinated.

“It’s clear that the vaccines are still having a substantial effect,” he said. Adding: “If you haven’t been vaccinated … there appears to be at least a two-fold increased risk of hospitalisation,” referring to data from Pubic Health England and Public Health Scotland.

When asked about variant that originated in Nepal, Dr Ferguson said that it was essentially the Delta variant with an important additional mutation — K417N. He said that it had also been associated with the Beta variant, which was first seen in South Africa, and that it too may compromise vaccine effectiveness.

He added: “We really don’t have data on this. It is a variant of interest at the moment in the UK and of some concern but data is still being collected.”

When considering the lifting of full restrictions on 21 June, Dr Ferguson said: “I think the data is pointing this week in a more negative direction than it was last week,” adding that the Delta variant has been doubling across the UK every nine days.

He said that more data was needed to have a clear picture of the full impact of the lifting of the last round of restrictions on 17 May, and that he expected cases linked to the Delta variant to accelerate even more.

He added : “We haven’t yet been able to pin down how it translate translates into hospitalisations. We’re seeing an hospitalisations in the north west, and a couple of other areas, but it’s too early to say, and that’s critical because we do expect vaccines to give a high level of protection still, but exactly how high its critical what size third wave we might see.”

On Mr Ferguson’s comments of the Delta variant being more transmissible, Robert Jenrick, the communities secretary, told BBC Radio 4’s Today programme: “It’s certainly true the India variant is more transmissible that it is growing, it is likely to become the dominant variant in the UK and these are all sources of caution. 

“But we’ll have to review all the data in the round before we make a final decision. There’s nothing today that would lead us to believe that we can’t move forward with the 21 June re-opening, but I think you can hear from the tone and the decisions we’re making in other respects, we’re applying an added degree of caution in the days ahead”.

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