Thread by @WilsonKM2

I've got a few minutes while dinner is still cooking before I start work again.

Let's talk about vaccine distribution.

I post some version of this graph every day. Solid line is doses distributed to the province, dashed are doses administered. Shade is the difference. Easy.

Here's Ontario for comparison.

From this one graph, you can get a quick sense of how much a province *can* vaccinate and how quickly it *is* vaccinating given that constraint.

But there's bunch of information trapped in that shaded area. (Argh! Trapped data!)

The two SARS-CoV-2 vaccines currently in circulation are Pfizer/BioNTech and Moderna.

They are both 2-dose mRNA vaccines. You get one dose and then the 2nd a set number of weeks later. After ~10 days you're at 95% lower risk of developing symptoms (hurray!).

Early on, the most common plan in Canada was for provinces to administer the first dose and then hold the 2nd in reserve to make sure that it was available when needed.

Sounds great. Except there's a pandemic and we're currently playing an exciting game of "how quickly can we get people vaccinated?"

Is there another way to approach this? Yes. We could give people their first dose and then not hold the 2nd in reserve. Give the 2nd dose to someone else as their 1st dose, and rely on the next delivery on the factory to get the 2nd dose.

What if the delivery doesn't come!?! The risk isn't zero, but I like to think of it in context.

Here in NS, to vaccinate everyone we need 2 million doses. So far: 2.720 done.

If we can't find another 2,720 doses, we have bigger problems than not being able to find 2,720 doses.

And pretty much instantly, that's what all the provinces started doing: cbc.ca/news/canada/to…

And I *thought* that included Nova Scotia: cbc.ca/news/canada/mo…

But based on a recent media release, I'm not sure! novascotia.ca/news/release/?…

They give a pretty detailed breakdown of each of the vaccines (doses received and used), so we can update the original chart:

Blue are Pfizer doses administered and Moderna doses already earmarked for use. Reds are doses for each* in reserve. Grey is doses not allocated.

*Technically I don't know if Moderna doses are being held in reserve, they don't say that explicitly in the release.

But the point I'm trying to make is that the answer to "Can we go any faster" depends.

If we hold doses in reserve: No. We've mostly expended our supply. We can't go any faster than we receive doses

If we don't hold them in reserve: Yes. We can go faster. We are less than half way through our supply.

Here's a great modeling study by @AshTuite, @zhulin0406, @DFisman, and @SalomonJA demonstrating the benefits of this approach (open access): acpjournals.org/doi/10.7326/m2…

@AshTuite @zhulin0406 @DFisman @SalomonJA I'm not sure which strategy NS is using (mixed messages), but I hope it's not holding up the process with excess caution.

That's a lot of red-shaded doses to sit in a freezer for three weeks.

Oh, back to work!

I have to put the surveillance study online.