So for 20 plus years my mother worked for a blood bank. It wasn’t the Red Cross but it was a volunteer donation whole blood place not a plasma donation place. At the same time she was working there, I was a teenager and deeply into a bunch of vampire RPGs and larping. I did a couple of my science fair projects with the people in her lab. While doing that, we talked extensively about how it would work to get blood out of this place without tripping any regulatory stuff for the lab or in general being detected by the staff.
While I assume that some of the laboratory technology has improved over the years, if you are in an environment where drinking from blood bags is sufficient for the vampires to survive, this presumes a couple of things:
One, blood does not have to be fresh from the human in order to be nutritious for the vampire
Two, the anticoagulation and other processes and chemicals inherent to the blood bags are not harmful to vampires
Three, the spinning down and splitting of blood into its component parts does not strip the blood of its nutrition, and in general bags of whole red blood cells are probably sufficient. There could be an argument that you also need to steal the platelets and plasma, but in any case a donation of whole blood is a sufficient meal for a vampire one way or another.
Four, given that we don’t see vampires checking the date on these blood bags, and especially in the RPGs you can steal whatever you want right out of the refrigerator and it doesn’t matter, we can presume that the blood continues to be good for the vampire as long as it is also good for transfusion into a human.
Given these presumptions, there are reasonably ethical ways to get your blood from a volunteer donation blood bank.
There are a number of ways that units can be spoiled right out of the gate. If you don’t donate enough blood, if it’s a bad stick or you just clot too fast, your blood bags can be too light (we measure blood by weight when you are drawing it) to qualify for human transfusion. Combining multiple of these bags that would otherwise be thrown away into a single unit could be a meal for a vampire without taking any blood out of the system that is intended for medical use.
Expired blood is dated well within the margin of error for the blood actually going bad in any real sense of the word. Obviously you want to make sure that anything set for human transfusion will be 100% ready 100% of the time. For a unit that expires in 30 days, it will likely be sort of past the sell-by date but still edible and likely still consumable by vampires. While many of those expired units are autoclaved, packaged, and sent off to pharmaceutical research facilities for use in testing and the like, there are other ways for those companies to get that blood, so pulling from the pipeline just after expiration date would almost certainly be an ethical thing to do and not harm anyone. This was the place in the process where the tracking of the blood goes from specifically tracking the serial number on each individual unit to simply counting the total number of units in a box. If you had someone on the inside who could fudge a few numbers for you and make sure the QC folks didn’t triple check your work, you could sneak blood out this way without causing any alarm.
Lots of people bag their own blood and do directed donations. Sometimes they want it for specific Medical procedures, sometimes they want it just in case, like if they have a particularly rare blood type and want to make sure if they’re ever in an accident they have a perfect match for their own blood. This blood is often kept Frozen and with a much longer expiration date than your average unit. If you had some individuals who you trusted to regularly donate blood for you specifically, you could likely get away with that and create a fake private Clinic that would purchase those specific directed donation units which were never in the main stream of blood donation. You could also pay someone on the inside to let you know when someone with banked blood has died, and you could get a bunch of Frozen blood in one go.
If you’ve ever got questions about blood donation, the transfusion pipeline, blood typing, or anything else similar, feel free to drop me a line.