VACCINE DATA USER GUIDE
Some notes here on how to use/read the data we post and gather from states + the CDC, and how we've chosen to present it. Treat this as a bit of a reader's guide for how to use the analysis, what it means and what it doesn't: http://bloomberg.com/graphics/covid-vaccine-tracker-global-distribution

2/ A few general things:
* Read column headers and labels closely
* Read our footnotes on maps + tables -- we tend to explain things there
* Pay attention to WHERE data is coming, and be aware it has limitations

3/ Our work/posting schedule:

We update daily around 6pm. Sometimes there's lots of data and it takes longer! Other times we get a big dump of international data and update earlier, or in the morning + then the afternoon.

If we're adding new features, it can be (lots) later.

4/ I'll update this thread as we add or change stuff, which will happen. And I'll not it in our daily updates when something changes. We are working on adding a blog so that this can live on the page itself, instead of on Twitter.

Okay! On to the details!

5/ Our map has two toggles: Vaccinations as a % of population, and share of SHIPPED doses used (more on that later, since it's in the table as well). The mouse-overs also show the NUMBER of doses administered in a state.

6/ We count DOSES. A dose means a shot in an arm, non-specific to whether it's a first dose or a second dose. Why do we count this? Because it's what states and the CDC report most consistently across jurisdictions.

7/ Some but not all states break out people who have gotten a first dose vs a second dose (aka vaccine series completion). We don't know yet if CDC will report these data. We're collecting them behind the scenes with the hope of adding it if the quality is good.

8/ We also count doses used per state as a percentage of what they've been SHIPPED. Our "shipped" number comes from CDC, and is updated regularly. It's pulled from CDC's VTrckS system, and the data comes from here: https://covid.cdc.gov/covid-data-tracker/#vaccinations

9/ We have STOPPED using Operation Warp Speed allocations, which are the amount of vaccine AVAILABLE to states, but not yet ordered or shipped. But we're still tracking the OWS allocations.

10/ SHIPPED means just that -- it's marked by CDC as having been ordered and sent. It could still be on a FedEx or UPS truck. It could be lost. It could have gone bad. It does NOT reflect actual inventory, but we think it's the best thing we have for now across all states/terrs.

11/ Some states report doses distributed. This sometimes matches CDC's "shipped" number, and sometimes not. But state definitions of this number aren't very consistent, only some report it, and some report it but don't update it.

12/ You can find those numbers here and mouse-over or sort them. It's our way of letting you see how fast states are using the vaccine they've ordered. It's very interesting now and will be for a while. Later, other stuff may be more important.

13a/ Because doses can be in transit or get wasted, this number is not perfect. The best number would be doses vs inventory. But we don't have that consistently. The ratio of administered/shipped will get more useful as the denominator grows

13b/ ....bigger denominator of doses shipped = smaller % that are in transit = more accurate number of how states are doing using what they've ordered.

14/ So where do we get our "doses administered" data? That's from a mix of CDC and state numbers.

15/ Many (most?) states now have vaccine dashboards. Some report via Twitter. Some email us. Some give updates at press conferences. We try and grab it all.

16/ CDC also has its dashboard, pulled from state vaccination tracking systems called IISs (and a web of other IT systems following vaccinations).

17/ We pick the BIGGER of those two numbers, assuming we trust it. We don't use numbers when they're something like, "by tomorrow we'll have vaccinated X people" or when we think it's a press conference and somebody might be rounding up.

18/ ALL of these data lag. The vaccination sites are given 72 hours to log vaccinations (you want people giving shots, not doing paperwork).

19/ CDC has said their current lag right now is about 50 hours. Some states are better than others. So know that when you see these numbers, there's an average of about two days of vaccinations that HAVEN'T been counted yet or posted by us or CDC.

20/ EVERYONE is working on trying to improve lag. CDC, states, etc. They want this data as close to real time as they can. It will also matter a lot less as the days and weeks go on and the denominator gets bigger. (Two days of lag matter a lot less spread over 100 days of data.)

21/ Some brief notes on our INTERNATIONAL data:

We have reporters around the world doing much the same as we're doing in the U.S. We get data from official sources and add it to our very, very big Google sheet. We update daily.

This data is less detailed than in the U.S. We mostly know number of doses given. Some countries give number of people vaccinated with both doses. Some do wonderful, clean presentation. Some put it up on Twitter.

21/ Expect it to evolve substantially, and along with it our presentation.

22/ There are some major caveats, though:

-China reports infrequently, and we don't know really how up to date the data is. So when we or others say this country or that is "ahead," it's based on our count, which is based on the data we have.

23/ We expect data reporting to get far, far more varied as more countries come on. Some will report great detail, every day. Others will report once a month. Others may only get reported by the WHO, six months from now. It's going to be a mixed bag.

24/ We stopped reporting "as of when" notations in the U.S. because with CDC and the state dashes, it's all typically within a day or two. Internationally we're still reporting it because it's way less consistent. That may change!

...That's it for now. I'll reply to any questions in thread, and post updates here as we have definitions/clarifications to add. Happy New Year!