The attack at the Pulse nightclub in Orlando this month horrified the world, but it was a particularly profound blow for the LGBT community.

Afterward, when calls for blood donations came roaring in, hundreds and hundreds of people lined up to give what they could. But for gay and bisexual men, this call was like salt in a fresh wound: During their community’s hour of need, their contributions were unwelcome.

According to the Food and Drug Administration, any man who has had sex with another man within the past 12 months is forbidden from donating blood.

Do these recommendations have the science to back them up? Or are they based on historical biases?

Until last December, men who have had sex with other men -- or MSM, as they are often designated -- and women who have slept with such men were forbidden from donating their blood at all.

The policy began with the AIDS epidemic in the 1980s. At the time, the virus was a strange and terrible medical mystery. In its early stages it even went by a different name: “GRID,” short for gay-related immune deficiency.

Thousands of people contracted the virus through blood transfusions and medication created from donated blood and plasma during this period of ignorance.

We now know much more about the virus – arguably enough to keep our blood supply safe – but our attitudes and practices don’t really reflect today's reality.

Testing is better. Immunoassays that screen for antibodies are the most common types of tests used to detect HIV infection. They can be done in as little as 30 minutes for an initial diagnosis, which can be confirmed with follow-up tests. They are “generally very accurate,” according to

There are also tests that can detect the virus in as little as three weeks after first exposure.

Prevention is also better. In 2012, the FDA approved an HIV prevention tool for those at “very high risk” called pre-exposure prophylaxis, or PrEP. It’s a combination of two HIV medicines, tenofovir and emtricitabine, which is taken daily to prevent those who are HIV-negative from contracting the virus. The pharmaceutical cocktail is now sold under the name Truvada and is widely available.

One study published earlier this year found that these drugs could lower one’s risk of infection by 86 percent. The Centers for Disease Control and Prevention cites studies that indicate up to a 90 percent reduction in risk. When used in conjunction with condoms, that risk drops even lower.

Treatment is better, too. A diagnosis of HIV is not the death sentence it was once considered to be.

Antiretroviral therapy (ART) uses a combination of drugs to fight the virus. There are currently six “drug classes” that fight the virus in different ways, which can be used in combination based on an individual patient’s needs. ART certainly isn’t perfect. It can’t cure HIV or AIDS — nothing can at this point — but it can help treat those infected and reduce the risk of partner-to-partner transmission.

So if testing, prevention and treatment are worlds better than where they were, why did it take so many years for the FDA to lift the lifetime ban? And why is the current deferral period still so long?

Mark Skinner, a past president of the World Federation of Hemophilia, believes it’s too risky to ease up any further. Until we have better screening tactics, he says, we need to be overly cautious.

“We acknowledge that it is a discriminatory policy,” Skinner said, "but discrimination in and of itself, while bad and should be minimized, is not wrong if it's in the interest of protecting the public health.”

Skinner, who has hemophilia, contracted HIV through medical treatment in the peak of the AIDS epidemic. He cites the prevalence of the virus in the MSM population compared to the heterosexual population as justification for the ban: It’s simply more common in MSM than it is in other demographics, and cutting them from the donor pool cuts down on risk.

The latest CDC data (which, it should be noted, was collected before the boom of PrEP) says that of the 44,073 estimated new cases diagnosed in 2014, around 67 percent could be attributed to “male-to-male sexual contact” alone. Another 1,217 cases involved men who had sex with men and also used intravenous drugs, where the exact mode of transmission couldn’t be certain. In contrast, just under 24 percent of those new cases came from “heterosexual contact.”

So it isn’t wrong to say that sexually active gay and bisexual men are more likely to be HIV positive. But if we looked more closely — at individual behavior — the FDA could throw away a discriminatory policy while making the blood supply even safer.

Right now, the pre-screening for blood donations includes a number of questions that Skinner says aren’t sufficient to guarantee healthy blood, particularly when it comes to sexual activity. So why not up the ante?

But Skinner worries that the types of questions that would be necessary could alienate the “Midwest soccer mom or NASCAR dad — somebody who comes from a red state.” Questions like how many sexual partners do you have, when were you last tested for sexually transmitted diseases, when did you last have sex without a condom, have you ever engaged in anal sex without a condom, and so on.

“[They’re] not used to having a discussion or being asked those kinds of personal questions,” he said. “Do we raise the possibility that we might actually scare off donors if we're going to be asking questions that they consider inappropriate?”

“You just need to understand the full 360 impact,” he added.

But the assumption that sexually active gay and bisexual men, by definition, participate in riskier behaviors than the rest of the population is misguided.

In fact, if blood donors were asked more probing questions about their sexual practices, then the argument against allowing gay and bisexual men to give blood would quickly fall apart.

Monogamous gay men would emerge as less risky donors than careless straight college students. A Midwestern mom who’d never been tested for HIV in her life might be riskier than a bisexual man holding recent test results in his hand. A NASCAR dad who refused to give screeners a run-down of his recent sexual partners might raise more red flags than a young man on PrEP.

Indeed, for David Stacy — the Human Rights Campaign’s government affairs director — it comes down to actual behavior, not sexual identity. Italy uses this kind of behavioral screening and hasn’t seen an increase in bloodborne pathogens because of it.

“If you're a gay or bisexual man who is having unprotected sex and they ask you these questions,” Stacy said. “And you say ‘well, yes that's what I'm doing,’ it would make sense for them to say ‘well, we're not going to take your blood because of this behavior, not because of your status.’ ”

Skinner says he would support a behavior-based approach if the science can back it up with certainty. The Human Rights Campaign just wants the FDA to “take a fresh look at this” and make new recommendations on science. Everyone wants to keep the blood supply healthy and safe.

The guidelines currently in place may try to ensure that safety, but they don’t seem to be able to fully separate scientific fact from flawed assumptions and prejudices of the past.