Thread by @Dereklowe

(1/8) The UK authorities are now trying to spread out the two doses of the Pfizer/BioNTech vaccine as well, in order to get more people the first shot now. A similar situation to what I wrote about yesterday: blogs.sciencemag.org/pipeline/archi…

I see why they’re proposing this, of course. The UK is in bad shape, with the new coronavirus variant spreading quickly. And we have evidence that the first shot really does seem to be immunogenic. BUT. . . (2/8)

. . . There are important things we don’t know. How long does immunity last if you’ve only had one shot? How well does the second booster shot work if the gap between them is longer? (3/8)

These concerns might work out OK. But they might not. We simply *do not know*, and human immunology is very much capable of dealing us either high cards or low ones here. It’s a gamble. No other word for it. (4/8)

That’s why Pfizer is telling the UK authorities that the vaccine has not been approved for use in this way. These ideas have never been put to the test, so the vaccine’s developers are unable to stand behind it under these conditions. (5/8)

The UK government is thus running a real-time experiment on its population in the hopes that the benefits of a first dose of its available vaccines (AZ/Oxford, Pfizer/BioNTech) will outweigh the risks of then messing with the dosing schedule. (6/8)

The horrible part is that there’s a good case to be made that running this big experiment (and taking on the risk of lowering the overall effect of the two-dose schedule) is still the right decision. Things are bad. (7/8)

But don’t pretend it’s not an experiment, or that we know what the outcome will be. This is a desperation move, and it’s a terrible thing that such a strategy has made it to the top of the list. I hope it works. (8/8)