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My pharmacy nerd brain that just read the pfeizer covid vaccine monograph is tingling. Clinical stuff side, the actual dosage form, preparation and storage are really interesting, from a "how do we get the most people vaccinated puzzle" point of view
First, it's mRNA, which is super cool! Also it's in lipid Nano particles, a really good way to distribute this mRNA within the body. It must be given IM, the lipid droplets containing the mRNA will be specially formulated for muscle tissue drug delivery
It comes frozen between -80 and -60 degrees Celsius in special thermal containers packed with dry ice and must be stored at this temperature long term. That's an issue for nation wide distribution I'm glad Canada is doing test runs as we speak
A cool thing in the monograph, if you don't have a mega freezer available, you can keep topping up the thermal containers with dry ice. This will keep the vaccine at a recommended temperature. We can creatively use this to increase access to the vaccine
The vaccine will thaw within a couple hours in the fridge, and then is stable for 120 hours. That is enough time to grab a small supply of vaccine, properly package it for travel at fridge temp and get to a remote spot to do injections. We can be creative with this
One word of caution here, the vaccine must not be shaken, or especially while thawed the lipid nanoparticles could be damaged. Careful packaging is a must
Once the vaccine is diluted for use it is stable for 6 hours, in the fridge protected from light and UV. NACI asks we do whatever we can not to waste doses, so if we have given 4 doses out of a vial and the next appointment is a no show then we grab whoever we can by priority
Each vial once prepared will have 5 x 0.3 ml doses. Must be diluted with sterile sodium chloride 0.9% for injection, nothing else. The wrong salt balance in the diluant will destroy the freeze dried particles.
The vaccine doesn't ship with diluant! That's a big thing to keep in mind when you are planning your vaccination clinics. Be prepared!
On the line of not wasting doses, to prepare the vial we add 1.8 mL of diluant, which will result in probably 2-2.3 mL of suspension. Now, each dose is 0.3 mL of the resulting suspension. Overfill is always a thing with injection vials, makes them easier to work with...
But, a careful person could theoretically get an extra dose out of some of these vials occasionally. The manufacturer will recommend not to, but the stuff left in the vial will be the same as the stuff in people's arms. As a cost cutting/dose stretching measure it's possible
I think Canada may fall down pfeizers list for follow up deliveries if we start getting extra doses out of vials though. Playing with 
