I've cheered up a bit on vaccine supply. The data is consistent with a pretty-much-OK trajectory in the coming months. (It's also consistent with disaster, but let's be happy.)

Also, people asked for sources/reasoning on some stuff I've posted already. So, some notes (1/10)

Historicals first. We can tell how much total vaccine stock has been fed into in the system. It's allocated to regions by population and the Scottish government tell us their share every Tuesday. https://www.gov.scot/publications/coronavirus-covid-19-daily-data-for-scotland/ (2/10)

The UK dashboards give total first and second doses given each day, and we can split these by manufacturer by using the weekly updated Yellow Card reports (with the Internet Archive to source historicals).

These numbers then constrain second dose schedules in the future. (3/10)

The Scottish government also made public their expected delivery schedule out to end of May. It was quickly taken down, but The Internet Remembers.

Cross-referencing the above sources shows that this supply schedule has been remarkably accurate until the end of March. (4/10)

Putting all these together you get a picture of our national stockpile by manufacturer and how it's evolved over time.

So for example, we can tell that we stopped using Pfizer stocks for first doses at the end of Feb, and started piling them up in warehouses instead. (5/10)

Now the outlook.

Status: Pfizer's fine. We need 6m for second doses, we have 5m in warehouses already, and 1m doses are being delivered each week. Even if we impose a rule that we need all the second doses in storage, we could (and should) restart 1st doses of 500k/week soon.

AZ is not so clear. The Scottish supply schedule had a big delivery from India that did not appear this week (as previously reported), but worse, there was zero domestic supply in its place. AZ had previously stated that they could produce 2m per week domestically.
(6/10)

There's a stockpile of AZ, but it'll be eaten up in a couple of weeks by scheduled second doses alone.

So, why have I become more cheerful? Mainly because two separate people have told me that their vaccination centres are cleared to administer AZ first doses. (7/10)

There's simply no way anyone would let that happen unless there was strong confidence that supplies of AZ were quickly going to be renewed.

So, let's be optimistic, and say we have >1.8m per week of (lumpy) domestic AZ supply.

Add reports of 2m Moderna by end of May, and...

Here's one example of a profile for April onwards.

It all fits. You get a pretty barren April in terms of first doses, but they get better in May and really start to ramp back in June. (9/10)

There are variations. If you're not sure of Novavax/J&J, you need to hold back ~3m Pfizer & Moderna doses from May & June to supply under-30s.

But pictures like this hit government targets, are solidly OK in terms of roll-out, and fit within the supply information we have.

Thank you for many interesting and generous comments. Three popular themes

1) Do J&J/Novavax/other change things?
2) I'm 43 years old, healthy and a Libra. With this outlook, when do I get vaccinated?
3) You mentioned disaster? What does disaster look like? We're so here for it

1) Yes, new vaccines change things. But probably only June onwards. I have not included them in the outlook because they have not been approved.

If they are, they come in particularly useful for providing an AZ alternative for under-30s, and putting the July target beyond doubt

I would caution that J&J seem to be having supply problems in the US, and the EMA has quietly opened an investigation into a similar blood-clotting issue to the AZ vaccine. Given they are a similar design, this may hint that J&J will not be suitable as an AZ-alternative.

2) When's my jab? Given the profile, it's fairly straightforward to work out when people of a particular age might be called for first doses.

There's a bunch of assumptions in this, all of which will be wrong, so this is probably a bad idea ...

But, here we go: earliest opening dates *if* the the age-groups continue to be called in strict order, *if* the uptake continues etc ...

Your most likely date to get a jab will be in the mid-point of the period between the earliest date to open and that of the next age-group.

3) OK, if you really want this ... the current data is *also* consistent with a looming crunch.

If the current disruption to AZ supply does not get fixed, or if ongoing supplies (likely domestic UK only) turn out to be much less than the 2m that AZ stated, then we have a problem

Timing and quantity both matter.

"Similar" and "Better" are versus the schedule shown earlier in the thread, and relate to the number of new first doses available.

"Bad" means further reductions of first doses in April/May down to only using Pfizer and Moderna (500 - 600k / wk)

"V. bad" means "bad" plus having to break the 12 week limit for some AZ 2nd doses.

The only good thing about this scenario is that real-world data suggests that AZ's 1st dose protection keeps building up to, and perhaps past 12 weeks. Unlike Pfizer's which starts to deteriorate

I had discounted this scenario, because there are still AZ first doses being planned for next week - and this would be daft if there was an AZ supply crunch. You'd want to eke out your stock for seconds.

But articles like this one make me nervous. https://www.gponline.com/first-dose-covid-19-vaccine-supply-gp-sites-stop-completely-fortnight/article/1712405

We will get another indication on Tuesday when the Scottish Daily Report updates to show their latest stocks - if there's no new AZ, this will be obvious.

So, if anyone wants to join me in hitting "refresh" on Scotland's Daily report page, I'll be there at 2pm on Tuesday.

There many other ways of going wrong (and of overperforming). But this AZ-crunch seems the most likely, given the numbers we have.

Needless to say, if anything like it occurs then the doses profile above, the dates for getting a jab and so on are all for the birds.

But I'm sticking with the optimistic outlook for the time being - it's in keeping with Cabinet Office long-term projections, with actions on the ground and with (most) of the noises from government [ends].