"Patients are more vulnerable than the donors, because they are being transfused out of necessity, not choice," he says. And a transfusion-transmitted HIV infection would be a significant harm the patient would otherwise not have been exposed to.
The FDA's screening program has been largely successful. According to its Web site, it has helped eliminate nearly 90 percent of unsuitable donors.
Yet much of the screening relies on the honesty of those answering the questions. There remains a risk that donors will lie about their medical history, misunderstand the questions posed to them, or not remember using intravenous drugs.
The possibility that these donors may be carrying the HIV virus could be compared with the possibility that a gay man is carrying the virus.
"They are part of a similar higher-risk demographic group," says Blumberg, who adds that taking a donor history is of little to no protective value to transfusion recipients.
Donor histories are "notoriously unreliable and now much less useful in screening blood donors than we would like to think," he says.
No one denies that the FDA has made great strides in providing patients with adequate supplies of healthy blood.
Critics only hope that its policy of banning an entire demographic comes from sound evidence.
"We're just trying to make sure that these decisions are based on science," says Ginsberg, "and not preconceptions about gay and bisexual men."