The business of blood plasma collection
The first step in the manufacture of Factor VIII / Factor IX concentrate products begins with collecting Plasma Donations (Plasma is the liquid part of blood that remains once the red cells and cellular components have been removed) and the companies that produced Factor would need lots of them.
In the United States and some other countries that Britain imported products from the donors were paid cash for their donation (See Newspaper Ads here). It had long been understood that paying a person for their donation was a bad idea, a payment presented a clear and strong motive for a donor to lie about their health status, particularly IV drug abusers.
Plasma collectors would often set-up their collection centres in poor "skid-row" locations where profits could be maximised, preying upon those who were more likely to carry viral infections such as IV Drug Abusers and Prostitutes. Pay-for-Plasma operations were even setup in Prisons where higher viral-risk activity, such as homosexuality and needle sharing was common place.