Some people with HIV pose virtually no risk of infecting their sexual partners. That claim, extraordinary as it sounds, is from a group of four highly respected HIV experts in Switzerland. As you can imagine, it's caused a lot of talk in the medical world. And here to fill us in is Day to Day's medical expert Dr. Sydney Spiesel. And Syd is at the Yale Medical School. He's also a pediatrician. And he writes for the online magazine Slate.

Hi, Syd.

Dr. SYDNEY SPIESEL (Pediatrician, medical contributor, Hi, Madeleine.

BRAND: Who are these HIV patients that the researchers say are not contagious?

Dr. SPIESEL: Well, they're patients who are receiving these new treatments -these highly effective antiretroviral treatments. And they have no HIV virus detectable in their blood for at least six months. And that's critical. All of these patients, the treatment has been continued for a long time. They've been monitored very closely. So no detectable virus for at least six months. They're on continuing treatment under close supervision of their treating physician. And they have no additional sexually transmitted infections, because that changes the risk of transmission a little bit.

BRAND: So how did these researchers conduct this research? What's the evidence for their claim?

Dr. SPIESEL: Well, they looked at older papers and the literature, and they looked at several things. First of all, they looked at papers which tracked HIV discordant couples - that is couples in which one member of the couple was HIV positive, the other one was negative - on highly active antiretroviral therapy. And in those groups, which had no measurable virus in their blood - where the level had dropped so low it was undetectable - there was no transmission.

They looked for evidence of the virus in genital secretions, and again it declined towards zero and un-measurable levels on these patients, who had been very actively and carefully treated.

BRAND: So is the idea then that these people who are showing no signs in their blood of the infection can just go out and have sex freely?

Dr. SPIESEL: If these conditions are met, then the risk of transmission of a couple where a condom isn't used, for example, is less than one in hundred thousand. That number is very low. It's very rare. But nobody could argue that it's zero. The question is: what do you do with very low probabilities.

BRAND: Well, Syd, I imagine there is a lot of objection to these findings, a lot of controversy to it.

Dr. SPIESEL: There certainly is. First of all, it goes contrary to what we've been teaching for many years, which is that HIV-positive people should absolutely use protection all the time. The one recommendation of this Swiss commission is not agreed with by many important other authorities, like World Health Organization and the American Center for Disease Control.

I think the worry is that, first of all, the Swiss analysis might not be correct or the claim at least hasn't been proven. That people won't understand the Swiss position. And people who are not following their strict criteria will think, well, it's really okay to have unprotected sex. So that increases the risk.

And the other possibility, of course, is that in much of the world - and certainly in the developing world - it's hard to have a system in which people are monitored so carefully, are getting these incredibly expensive but very hard quality drugs.

BRAND: So take away message being…

Dr. SPIESEL: Well, the take away message - the CDC and the World Health Organization recommendations are to absolutely continue to use condoms.

We don't know what's going to happen. My own guess is that there's likely to be a kind of experiment in nature. Some HIV-positive people, like everybody else, are likely to be sort of, under certain circumstances, overtaken by passion, by impulse, by impatience and are going to have unprotected sex. And, you know, the whole thing still makes me very nervous - the idea of unprotected sex of people who are HIV-positive. But time may answer that question even more fully than it's presently answered.

BRAND: Thank you, Syd.

Dr. SPIESEL: Thank you.

BRAND: That's Dr. Sydney Spiesel. He teaches at the Yale Medical School. And you can read his Medical Examiner column at

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