> Can't help but feel the UK had incredible luck on their side here.

Some people might call it incredible luck, while others might say that it was a good decision made by world leading vaccine experts informed directly by the scientists who created the vaccine.

In fact, the BMJ said at the start of January:

> The trials of the Oxford-AstraZeneca vaccine did include different spacing between doses, finding that a longer gap (two to three months) led to a greater immune response, but the overall participant numbers were small. In the UK study 59% (1407 of 2377) of the participants who had two standard doses received the second dose between nine and 12 weeks after the first. In the Brazil study only 18.6% (384 of 2063) received a second dose between nine and 12 weeks after the first.3 The combined trial results, published in the Lancet,4 found that vaccine efficacy 14 days after a second dose was higher in the group that had more than six weeks between the two doses (65.4%) than in the group that had less than six weeks between doses (53.4%).

So there was knowledge/thoughts when the decision was made that an extended gap could change efficacy.

Besides, let’s give the UK’s biomedical community more credit than assuming it was a fluke anyway!

Depends what you mean by "little". At the start of the year, if not the end of 2020, there were studies showing the prevailing effectiveness with delays on the second shot so it was pretty clear where the trend was.

And then, merely hours ago, they decided because of the Indian variant they'd instead change the recommendation from 12 weeks to 8. So, at least in my opinion, it's a bit of a random walk down statistics street.

I know our govt can be swines but we still have a pretty amazing scientific / medical community here.

Not much positive to say about the handling of covid but when it comes to vaccine plans they've really done brilliantly.

Probably because it's scientists, doctors and the NHS that have handled it and not the government.

You’re correct, no evidence at the time JCVI (joint committee for vaccination and immunisation) made the call. However the decision was made on best interests [1] from a public health perspective. Delaying to 12 weeks allowed absolute numbers of people to be immunised once and build up some immunity versus absolute numbers of people vaccinated twice and having higher number of vulnerable populations without any immunity. Of course, this wasn’t taking into the people who had had COVID-19 and had a level of immunity to the virus from exposure.

[1] https://www.gov.uk/government/news/statement-from-the-uk-chi...

> You’re correct, no evidence at the time JCVI (joint committee for vaccination and immunisation) made the call.

This isn't true, the JCVI did have evidence. In fact their statement showing reasons behind the call said:

"There is evidence that a longer interval between the first and second doses promotes a stronger immune response with the AstraZeneca vaccine."

https://www.gov.uk/government/publications/prioritising-the-...

(Statement first released on 31st of December 2021, only available via google archive https://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&c...)

Delaying the 2nd dose to 12 weeks was always most likely going to elicit a better response, this is customary for vaccines. It would have been much more supposing scientifically if this much shorter timeline did better. The UK's approach was never much of a gamble.

I think luck is the true national skill of the UK. We are a nation of gamblers and risk-takers, and often that tends to lead us down paths that make no or little sense, but _sometimes_ we get really, really lucky.