Plasma is in blood, but it’s not the same as blood. It’s mostly water, but many labs use it to create therapy meds for some types of cancers and other autoimmune diseases. There’s stuff in plasma that helps fight disease. Basically they take it out of your blood then return your red blood cells to you. You won’t need the cookies and juice unless you had a reaction that worried them.

In the U.S., people don’t get paid for blood donation, but they do get paid for plasma donation.