Dominic Cummings (who is a keen LW reader and agrees with Zvi's most cynical takes about the nature of government) is likely a major factor, although he was gone at the time the first doses first issue arose, the overall success of the UK's vaccine procurement can be credited to the vaccine taskforce which was an ad-hoc organization set up to be exempt from much of the usual rules, partly due to his influence and that of Patrick Vallance, the UK's chief scientific advisor - that way of thinking may well have leaked into other decisions about vaccine prioritization, and Vallance certainly was involved with the first doses first decision. See this from Cummings' blog:
This is why there was no serious vaccine plan — i.e spending billions on concurrent (rather than the normal sequential) creation/manufacturing/distribution etc — until after the switch to Plan B. I spoke to Vallance on 15 March about a ‘Manhattan Project’ for vaccines out of Hancock’s grip but it was delayed by the chaotic shift from Plan A to lockdown then the PM’s near-death. In April Vallance, the Cabinet Secretary and I told the PM to create the Vaccine Taskforce, sideline Hancock, and shift commercial support from DHSC to BEIS. He agreed, this happened, the Chancellor supplied the cash. On 10 May I told officials that the VTF needed a) a much bigger budget, b) a completely different approach to DHSC’s, which had been mired in the usual processes, so it could develop concurrent plans, and c) that Bingham needed the authority to make financial decisions herself without clearance from Hancock.
(I see the success of the UK vaccine taskforce and its ability to have a somewhat appropriate sense of the costs and benefits involved and the enormous value of vaccinations, to be a good example of how it's institution design that is the key issue which most needs fixing. Have an efficient, streamlined taskforce, and you can still get things done in government.)
Other differences that may be relevant: this UK Government arguably has much more slack than the US under Biden or Trump. The UK's system gives very broad powers to the executive as long as they have a majority in parliament, this government is relatively popular due to the perception that it followed through on getting Brexit done, and we were in the middle of an emergency when that delay decision was authorized. Also, vaccine hesitancy is significantly lower in the UK than the US, and therefore fear of vaccine hesitancy by policymakers (which seemed to be driving the CDCs intransigence) is also significantly lower.
On December 30, 2020 Boris Johnson gave a speech in which he announced that the UK would follow a COVID-19 vaccination dosing schedule with a twelve week gap between first and second doses, instead of the 3 weeks that is standard in the US (and the rest of the world? [edit: Orual reports that Canada also used a dosing schedule that prioritized first doses]).
Verbatim:
As near as I can tell, this is a straightforwardly good policy in terms of public health, because it increases society's total heard resistance to the virus faster. But it also entails deviating somewhat from the specific conditions of the trials in which the vaccines were tested. If it turns out to be a bad idea somehow, you can't fall back on saying that this plan was standard practice, and you couldn't have done any better." So in some sense, it's a risk.
I would really like to know what causal factors were upstream of this decision. Why did this happen in the UK, but not in the US or elsewhere?
Are there specific individuals, in the limelight or behind the scenes that pushed for this outcome? Is the difference that, in the UK, someone was in the right place at the right time?
Is this a cultural thing? Does the UK government feel more comfortable choosing policies that make analytic sense, but which don't have the social stamp of approval of "The Science"?
And if it is cultural, what is the difference? Do UK politicians reason from physical models of the virus more than US politicians? Does the UK government expect that if they're attacked for a decision like this, that voters (or someone else?) will back them up, while that's not the expectation in the US? Does the UK government feel like it has credibility, and therefore can make strong, reasoned, recommendations, while the US feels like it doesn't have the slack to do that? [1]
Insofar as Britain was marginally more sane, on a societal level, than the rest of the world, it seems important to find out what made the difference.
Some additional relevant information:
Wikipedia says that there was some push-back against this decision by the British Medical Association, and Brittan's Chief Medical Officers published an open letter defending the decision.
That open letter is here.
It briefly expresses a simple argument for prioritizing first doses, of the sort that I and most Less Wrong readers would make. (There is a limited amount of vaccine; most of the immunizing effect comes from the first dose; it is more beneficial to public health for a marginal person go from 0% immunized to ~75% immunized than to have one go from ~75% to ~90%; therefore, given the tradeoffs, it makes sense to focus on first doses for the time being.)
This letter seems notable to me for being basically lucid and sensible, in contrast to much of what the CDC, for instance, has said this year.
[1] - In this post Zvi quotes Dr. Fauci (from here), saying that the US switching to first doses first would hurt credibility, because it would entail sending mixed messages:
(Note that the quoted article was published in March, more than two months after the UK announced their dosing schedule. Switching in March does seem more confusing than using a 12 week schedule from the get go.)