Germans less interested in moving fast and breaking things than Brits in my experience. Especially outside of Berlin.

Labour market and taxation are more flexible over here than on the continent. Also London was/is basically the financial capital of Europe, and the easiest destination for young talent for cultural reasons (it's easier for developers to learn English to a passable level than German, French, or less popular languages, when most of the ecosystem is built in and around English).

This said, Berlin started later than London but, from what I hear, got much hotter in the last 5/10 years, so there might be some rebalancing in progress.

I think it's related to risk-aversion of investors in EU. While spitting out millions of dollars anything with a slight chance of success is common in the US (and to some degree in UK apparently), EU investors are much more conservative in their spending, which affects the valuation of these companies.

I can see in that list some that have HQ in London, but their origins and main teams are still in other countries. This is mostly due to investor's requirements to relocate.

Other countries (e.g. Spain and Germany) have a lot more bureaucracy and fees around starting a company.

Here's a helper question: have you seen Bayer producing a Covid vaccine?

Nope, they're happy producing aspirin. Less risk.

Merck is currently testing two vaccine candidates (Sanofi is too actually). They started development later and took more time but when all will be said and done, I fully expect them to have shipped more vaccines than Moderna and Pfizer: mRNA-based vaccines have never been produced at scale and the logistic involved seems rather complexe.

Merck and Sanofi are developing vaccines based on existing vectors. They can reach true mass production as soon as they get approved. It's the same thing for Johnson and Johnson actually. AstraZeneca has what I would call a true headstart however.

... Of the major vaccines currently, Moderna was developed in the US, Pfizer/BioNTech in Germany (BioNTech, which developed it, is German), Oxford/AstraZeneca in the UK.

BioNTech produced it but Pfizer financed it. And the Oxford one is in the UK where all the "unicorns" come from.

Well, Bayer doesn't produce vaccines.

But yes, there is risk avoidance in the German market (but the language barriers kinda make some startups look "invisible" outside of their non-English speaking countries)