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Comment by corin_ | Hacker News Reader

HIV doesn't show up immediately (possibly other STDs are the same, not sure off the top of my head), if I remember correctly most people will test positive within 3 months of being infected.

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This is correct. Why isn't the question "Have you had unprotected sex in the last 3 months? Can we give you a blood test today?"

This seems a lot more sane than "There's this group that we used to consider high risk for HIV. We're not willing to scientifically test for it. Are you a part of this group?"

They would do the test on your blood regardless (they do it on all blood).

Regarding the 3 months: the UK only just changed it from a lifetime ban for MSM to 12 months - they feel that 12 is safer, many people have argued that this is still over the top. I'm not a doctor, and I'm not well enough informed to tell you who is right on this. Countries that do have a lifetime ban certainly need their policies updated.

Regarding unprotected: the argument is that even protected sex isn't 100% safe. I don't have any stats to argue for either side here, and I don't have an opinion for that reason.

So, it's not entirely a case of "we can't be bothered to test", but at the same time many countries have out of date policies. And even those, like the UK, with better ones, there are still some people who argue they are too strict against MSM, and others who argue that any less strict would be too dangerous.

The policy still doesn't add up. They really should just ask anyone if they've had unsafe sex outside of a monogamous and std tested relationship in 3/12 months.

I could very well have had sex with 100 women in the past 3 months (as a man) and been unsafe with all of them. Yet, they don't seem to be the least bit worried about that scenario.

While I support allowing homosexuals to donate, I don't think your comparison is fair.

Having 100 random sexual encounters with randomly sampled women leaves you approximately a 50% chance of having unprotected sex with someone who has HIV. Not to mention, HIV may not even be transmitted even if you have an encounter.

On the other hand, after 100 random homosexual MSM encounters, your chances of having had unprotected sex with someone carrying HIV is 99.99997344%.

MSM puts you at a much higher risk for HIV. That's fact.

Please, provide citations for your figures.

The standard HIV test people do (ELISA) tests for the antibodies produced against HIV, not the HIV strain itself.

Donated blood is tested with PCR, which detects the HIV RNA. PCR test detects HIV in as quick as a couple of weeks.

However, because of the added cost (and time cost) of running PCR tests, donated blood samples are pooled before being tested. If the test runs positive, samples are tested individually.

Ah very good then. Well since the CDC now says that blacks and women are the most at-risk for HIV, we should probably change the rules with the times then, right?

What's that? It now sound horribly offensive, erroneous, and bad policy? Well sorry about that! Gotta be consistent you know.

You're wrong on the facts part, as of this month the CDC still states "men who have sex with men (MSM) of all races and ethnicities remain the population most severely affected by HIV", with their estimated stats being that 2% of the US population are MSM, and they accounted for 61% of new HIV infections in 2009. MSM accounted for 49% of HIV infections in 2008. (Those years are most recent available data.) For more details check out their PDF at http://www.cdc.gov/hiv/resources/factsheets/PDF/us.pdf

(I'm not black or a woman, but am gay - for my own selfish sake I'd love what you said to be true.)

Good point. Very few people seem to be aware of the actual statistics on this subject, and not terribly interested in debating it further once once someone links to actual data which is quite frankly unequivocal. A bit ironic considering how self proclaimed enlightened people tend to look down their nose at the "uninformed" masses who think HIV is a "gay disease".

I have no issue with gay people at all, and on an absolute numbers basis, infection rates are not terribly high within that overall community. I just find it immensely interesting how people's normal thought processes (even those who are normally extremely logical and data oriented) are fundamentally altered when the subject of discussion is race, gender, sexuality, or culture.

Thanks for pointing it out.

I'm also aware of the statistics - roughly split between gays and heterosexuals. I think the problem lies more with the epistemological side of things. As the marrow registry, how do you know whether or not someone is gay? How do you know whether someone is HIV positive? Only one of these questions actually matters for donors, and only one of them is scientifically testable.

I'd agree with people who are okay with profiling if there wasn't a reliable test for HIV, or if there weren't enough resources to test for it, but I haven't found any evidence for either of those potential claims.

To hell with screening, if I was on death's door courtesy of leukemia I'd rather accept a transplant from someone I know is HIV positive. My logic: given the state of anti-retrovirals, being HIV positive sounds downright cushy compared to dying of leukemia.

I'm pretty sure you could get that operation, but not on health insurance of any kind.

yes, that's the report that went out yesterday. The context of the discussion was "at-risk" in the spirit of "have it but don't know it" or "don't know what to do about it"; not in the spirit of "have it". You can go over to the early release of the data here: http://www.cdc.gov/mmwr/preview/mmwrhtml/mm60e1129a1.htm?s_c... ... the people that get the least counseling, don't think they are at risk, etc, are those two groups.

They are the ones that are most likely to have it and not know it or treat it and are also the ones to face the largest stigma in dealing with the issue.

That's the context; it was the time window after infection but before high confidence of the results in the mouth swab test, which is the standard method used in such circumstances (and also the cheapest).

Anyway, that is what I meant by it, and that's the report I was referring to when I said CDC. I didn't mean to say that gay people don't get it.

The prevalence rate for MSM (about 20,000 / 100,000)[1] is much higher than for black women (1,122 per 100,000)[2] or black men (2,388 per 100,000), though you are correct that all three groups have very high concentrations of HIV positive persons.

[1]http://healthland.time.com/2010/09/26/study-20-of-homosexual... [2]http://www.cdc.gov/hiv/topics/surveillance/resources/factshe...

Well the STD test was only going to be able to rule-out donors who are positive at the time of sign-up anyhow. After submitting to the test and giving their sample, everyone becomes potentially infected until you test them again.

I suppose the idea is not to waste time and resources on ineligible donors, and it seems as though they've made the decision that profiling based on sexual orientation is the best balance between wasting time and resources tracking patients who are ineligible or will likely become ineligible and missing out on potential matches.

I just can't believe that an inclusive and scientific approach - don't profile, test at sign-up, test again at match - wouldn't yield more matches (and more positive goodwill, obviously). Then again I haven't seen the data...

Because testing can show the blood to be clean even for someone who does have HIV, and blood/marrow aren't (I believe / assume) things you can just stick in a fridge for a couple of years and then test again.

From wikipedia: "The vast majority of people (97%) have detectable antibodies by three months after HIV infection; a six-month window is extremely rare with modern antibody testing."

So if the transfer can work with a 3 month delay (I'm not sure if it can, just assuming), and the HIV test comes back clean, you're going to have a 97% chance of a true-negative, 3% chance of false-negative.

At that point, comparing it to the odds that the "eliglble" donor is lying about their sexual activities or is simply HIV positive and heterosexual, the ban on letting gays register seems draconian, and a scientific test-based approach seems better all around.

Especially when you consider that if no donor is found, the patient could die anyway. So if the only donor is gay, test them, and then notify the patient of the 3% chance of contracting HIV from a false-negative patient versus the 100% odds of dying from Leukemia, and see what decision they make.

http://en.wikipedia.org/wiki/HIV_test#cite_note-7

It isn't a 3% chance of a false negative, the 97% figure is conditioned on actually having HIV. The actual chance of a false negative is far lower, since most people don't have HIV at all.

Good point. You could also realistically eliminate those who know they are infected from the potential false-negative category, which would give you an initial pool of 240,000[1] potential infected who don't know they're infected. Among them there is a 3% chance of non-response within 3 months to antibody testing, for a total of 7,200 false-negative potential candidates out there among 309,000,000 total Americans. Then consider the 1 in 20,000 odds [2] of being a match, and you end up with a false-negative match rate of 0.00117 per million people (according to wolfram alpha [3]).

I probably screwed something up, but in any case you are definitely right that the false-negative odds are very low among all potential applicants. Really makes the argument against seem foolish.

1) http://www.cbsnews.com/8301-504763_162-57333212-10391704/cdc...

2) http://www.organtransplants.org/understanding/marrow/

3) http://www.wolframalpha.com/input/?i=%28%281%2F20000%29++*+%...

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