Thread by @john_actuary

The latest PHE surveillance report on Delta is now out. A flash summary on some key points.

The analysis of cases/admissions/deaths now helpfully includes an age split at 50. Of 109 deaths over 50, 38 were unvaccinated (a third), yet represent ~5% of that population.

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Nevertheless 50 who died had received both jabs. Remember though that no vaccine is 100% effective, and the risk factors are many times higher in the fully vac'd group because of the priority ordering.

This recent note explains in more detail.

https://twitter.com/john_actuary/status/1406571683947991041

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In the last couple of weeks for which data is available, there seems to have been a big increase in the proportion of cases via hospitality, consistent with the reopening of indoor venues in mid May. Education setting fell with half terms.

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You can see here how the growth in Delta has been predominately in the under 30s groups, whom are only now going through the first stage of the vaccination programme. Even allowing for lower population numbers, there's much less prevalence at older ages.
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There's been a slight increase in the estimate of first dose effectiveness against symptomatic disease, but it's still only 35%. Against two doses it stays around 80%, but that's still twice the level of escape as for Alpha.

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In contrast, against hospitalisation there's no evidence (given the CIs) that it is any more or less effective than against Alpha, and after 2 doses is 96%.

So having that 2nd dose reduces vaccine escape from 20% to 4%, an 80% reduction is risk. You know it makes sense!

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The secondary attack rate comparison with Alpha has fallen this week to 35% (from 42%) as the estimate is refined with more data. That's more encouraging news. The absolute figure has fallen too from 11.4% to 10.7%.

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Thanks as always to the terrific team at PHE for producing this huge volume of data like clockwork each week, and for continuing to enhance the information in it.
assets.publishing.service.gov.uk/government/upl…
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Note also this interesting thread from @JamesWard73 regarding the inter-relationship between SAR for household and non-household contacts.

https://twitter.com/JamesWard73/status/1408362431710126080