Thread by @fascinatorfun

Late yesterday PHE released a new chart regarding vaccine efficacy.

Welcome that it displayed data separately for Pfizer and AZ and fir Alpha and Delta variants

However the outcomes are markedly different from the table c3 weeks ago and markedly different from the Scottish data

This is the chart and the link.

khub.net/web/phe-nation…

It is a pre print so there pay be changes.

Also not much in the way of supporting data (with wide confidence intervals

They suggest similar second dose efficacy AGAINST HOSPITALISATION Pfizer (96%) to AZ (92%)

In fact marginally better 2nd dose performance against delta than Alpha.

But we know nothing of the respective cohorts or numbers involved, age groups and timescales and it seems prudent to wait for that.

The Scottish study was published in the Lancet and looks at both infections and hospitalisations re both vaccines.

Still v good performance against hospitalisations, but double the risk of hospitalisations in DELTA than ALPHA.

thelancet.com/journals/lance…

📌1 April to 6 June 2021 :19,543 community cases & 377 hospitalisations where a specific variant of COVID-19 was confirmed.

📌Of these totals, 7,723 cases & 134 hospitalisations = Delta variant. People with underlying conditions were more at risk of being hospitalised

📌. Overall, a strong vaccine effect did not clearly manifest until at least 28 days after the first vaccine dose (HR 0·32, 95% CI 0·22–0·46; appendix p 3).

📌 Among S gene-negative cases (ALPHA VARIANT), the effect of vaccination (at least 28 days after first or second dose) was to reduce the risk of hospital admission (HR 0·28, 95% CI 0·18–0·43) compared to unvaccinated. 👏

📌The hazard ratio for risk of hospital admission for S gene-positive cases (ALPHA) was 0·38 (95% CI 0·24–0·58), with an interaction test p value of 0·19, suggesting that there was no evidence of a differential vaccine effect on hospital admissions among those first testing +ve

When it comes to protection against infection (which, in turn, is likely to have knock on consequences for TRANSMISSION and R rate)

📌at least 14 days after the second dose, BNT162b2 (Pfizer–BioNTech vaccine) offered very good protection: 92% (95% CI 90–93) S gene-negative (ALPHA), 79% (75–82) S gene-positive. (DELTA)

So good VE re INFECTIVENESS from Pfizer, but lower for DELTA than ALPHA

📌 Protection associated with ChAdOx1 nCoV-19 (Oxford–AstraZeneca vaccine) was, however, substantial but reduced: 73% (95% CI 66–78) for S gene-negative cases (ALPHA) versus 60% (53–66) for those S gene-positive (DELTA)

So substantial but lower VE re INFECTIVITY re AZ than Pfizer and re DELTA v ALPHA .

It may be a question of timing, needing larger numbers and details of cohorts involved. Anecdotally DELTA is bringing in a younger cohort to hospitals so more complete data would be welcome

ArgH? SGene Positive is DELTA not Alpha.

So sorry

So, returning to the PHE chart that landed late yesterday.

The confidence intervals are pretty wide (insufficient numbers / ? Cohorts?) and the landing point for VE hospitalisation does not seem to be in the centre of the CI point

More information/ data might help elucidate

I have not commented on the VE re infections as I would@like to know the raw numbers involved.

The other reason I think it would be wise to wait for more granular data is that this Crick Institute study looks at Pfizer v DELTA and it suggested a similar reduction in neutralising Abs as BETA ( 🇿🇦 ) and also waning esp in older cohort after 3m

https://twitter.com/davidlvbauer/status/1400580669244428289

And this study

https://twitter.com/longdeserttrain/status/1404748055379910656?s=21

We may end up seeing some strong T and B cell responses but that is not the subject of the current data output.