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Since I see a lot of questions this evening about Pfizer's vaccine vials having more vaccine than expected, let's talk quickly about a word you might not have heard before:
Overfill.
Some tweets to follow in the thread below.
Overfill.
Some tweets to follow in the thread below.
First, for context, you should go read this exclusive that my colleague @owermohle broke today.
(And go follow her! She's awesome!) https://www.politico.com/news/2020/12/16/pfizer-vaccine-extra-doses-447117
(And go follow her! She's awesome!) https://www.politico.com/news/2020/12/16/pfizer-vaccine-extra-doses-447117
Ok, now: Let's say a manufacturer makes a vial of an injectable medicine.
That medicine is administered in some amount. Let's say 0.3 mL (the amount of Pfizer's vaccine).
If you had a vial for a single person, the vial would contain 0.3 mL... right?
Probably not, actually.
That medicine is administered in some amount. Let's say 0.3 mL (the amount of Pfizer's vaccine).
If you had a vial for a single person, the vial would contain 0.3 mL... right?
Probably not, actually.
Manufacturers slightly typically "Overfill" a vial to account for two main factors:
1.) That it's difficult to get every single speck of medicine out of a vial; and
2.) Sometimes the medicine might get spilled, etc.
1.) That it's difficult to get every single speck of medicine out of a vial; and
2.) Sometimes the medicine might get spilled, etc.
This can be a bigger deal when you have a multi-dose vial, which might need to accommodate a person withdrawing too much of a product as well.
So if you had a vial intended for, say, 5 people, you might have a lot of overfill.
CDC info: https://www.cdc.gov/injectionsafety/providers/provider_faqs_multivials.html
So if you had a vial intended for, say, 5 people, you might have a lot of overfill.
CDC info: https://www.cdc.gov/injectionsafety/providers/provider_faqs_multivials.html
And the cumulative amount of that overfill might even add up to an entire additional dose if you were careful about withdrawing individual doses in exact amounts.
Now, it's worth noting that this isn't a new concept to FDA.
The FDA even has a guidance document specifically on overfill.
(Read it here: https://www.fda.gov/regulatory-information/search-fda-guidance-documents/allowable-excess-volume-and-labeled-vial-fill-size-injectable-drug-and-biological-products)
A few highlights:
The FDA even has a guidance document specifically on overfill.
(Read it here: https://www.fda.gov/regulatory-information/search-fda-guidance-documents/allowable-excess-volume-and-labeled-vial-fill-size-injectable-drug-and-biological-products)
A few highlights:
There are a few things to watch out when dealing with overfill. The biggest is undoubtedly contamination.
The more frequently you go back to a vial (over time), the greater the risk of bacterial contamination.
From FDA's guidance:
The more frequently you go back to a vial (over time), the greater the risk of bacterial contamination.
From FDA's guidance:
I can't actually find any reference to overfill in the FDA's documents or decision memorandum, but Pfizer told Sarah Owermohle that the amount varies. (Less clear: By how much).
So, yeah. Overfill.
Another word you probably didn't think you would need to know about in 2020, but now...
Another word you probably didn't think you would need to know about in 2020, but now...
