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Why has the UK changed its vax regime to prioritising a single shot, going outside approved regimen for Pfizer (delay second shot) and commencing AZ, also with up to 12 week delay for second shot?
Here’s their thinking: https://www.cas.mhra.gov.uk/ViewandAcknowledgment/ViewAttachment.aspx?Attachment_id=103741
Here’s their thinking: https://www.cas.mhra.gov.uk/ViewandAcknowledgment/ViewAttachment.aspx?Attachment_id=103741
On Pfizer one shot gives coverage of circa 91% vs severe disease for short term. Publicly available data. I’d like to see the primary AZ data but the prelim data are reported as 70% in short term. Trials are not directly comparable for many reasons. But assume 70%
So you can cover x2 number of people for next 12 weeks at 91% coverage or 70% coverage vs 95 and 80% for Pf and AZ which a second shot. So the decision is made to go for x 2n people rather than increase 1n from 91-95 or 70-80
It’s unconventional to go outside licence at such scale and to postpone so many promised second shots in the vulnerable but equipoise- vax supplies are limited and ICU beds in London are a huge concern. It’s a war cabinet call as much as conventional regulatory medicine
If the vax arrive in time to deliver second shot at 12 weeks (understood to be outer reach of timing of second vax) this looks like a plausible strategy, not without risks, that other countries will certainly have to consider, at least to bridge to April.
I’m glad not to have to make these calls and wish those involved in making these difficult choices in all counties well
