Spotlight Center on HIV Prevention Today


HIV Undetectable Does Equal Uninfectious: The Swiss Statement and the Vindication of Pietro Vernazza

October 7, 2016

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Continued Hesitance

But just because 052 and PARTNER have validated Vernazza's 2008 statement doesn't mean resistance to the undetectable equals uninfectious concept has evaporated.

When asked whether they would sign on to the Swiss Statement if it were released today, only Hillier and Jared Baeten, principal investigator of the Partners PrEP trial, said unequivocally that they would. Lundgren said he would, but only with the caveat that we still need more information about treatment's impact on transmission via anal sex -- which the final results PARTNER will address.

Cohen would sign on, too, he said, now that we have the data from HPTN 052 and other studies. But scientists still need to understand why the virus continues to shed into the genital tract, even when people are on antiretroviral therapy, he said -- something that he said could both affect the risk of transmitting the virus and provide information leading to a cure.

"As long as you stay virally suppressed, it's durable prevention," Cohen said. "But if you stop being virally suppressed, transmission becomes possible again. So we don't believe we've achieved some sustained prevention in the absence of antiretroviral treatment."


And you could stop being virally suppressed for reasons that have nothing to do with whether you take your meds every day, said Kalichman, who works primarily on adherence myths and treatment beliefs (such as the belief that antiretrovirals cure HIV rather than suppressing the virus as long as you continue to take them).

"The big ringer in this is genital tract inflammation," he said. "That's why, for example, in Vernazza's research that the Swiss Statement was based on, the people in those studies, the men, were tested for STIs and clinically cleared for STIs every three months or something. That's also true on 052."

To him, the message isn't that treatment makes one uninfectious, but that treatment along with regular viral load tests showing an undetectable viral load and excellent sexual health care every three to six months makes one uninfectious. It's a system of care, not a magic pill.

"If you just assume that if you're adherent, then you have an undetectable viral load in your genital tract, you're wrong," he said.

Maybe that's why some public health policy people are still hesitant to endorse the Swiss Statement. Take Eugene McCray, M.D., director of the CDC's Department HIV/AIDS Prevention. He said in an email to that we've come a long way since the Swiss Statement. But he wasn't willing to go so far as to say that undetectable equals uninfectious.

"HIV treatment is a powerful prevention tool," he said, "but [it] alone is not sufficient to stop HIV transmission."

That hesitance may be showing up in medical publishing, too. Soon after Lundgren and the PARTNER team presented their data on condomless sex, suppressive antiretroviral therapy and HIV transmission at CROI in early 2014, they submitted the data to medical journals. Several passed. Finally, the Journal of the American Medical Association (JAMA) published the paper in April 2016.

That's 30 months from presentation to publication and 14 months for JAMA to review and publish the article.

It's a lag time that Lundgren said is "an unusually long time for an editorial process of a submission." And indeed, Kalichman, who edits the journal AIDS and Behavior, said that while every journal's process is different, 11 months was the longest it had taken his journal to review and publish.

And though Lundgren said he doesn't often think about the delay anymore, he added that "the long time from first presentation at CROI to eventual publication has created some degree of frustration within the wider scientific community, which didn't understand why the paper was still not published."

Vernazza, who was on the executive board of the PARTNER study and is listed as one of its co-authors, suspects that the same attitude that informed responses to the Swiss Statement continues to color responses to the hard data.

"It wasn't that the data was bad; it was because [journal editors] didn't like to show the evidence," said Vernazza. "It was unacceptable, this process -- which tells you there were other forces that tried to push this publication back. That's my assumption based on experience."

Howard Bauchner, editor of JAMA, did not respond to an email seeking comment.

A New Consensus

In July, not long after Cohen presented the final results of HPTN 052 at IAC, the advocacy group Prevention Access Campaign came out with this statement:

People living with HIV on [antiretroviral therapy] with an undetectable viral load in their blood have a negligible risk of sexual transmission of HIV. Depending on the drugs employed it may take as long as six months for the viral load to become undetectable. Continued and reliable HIV suppression requires selection of appropriate agents and excellent adherence to treatment. HIV viral suppression should be monitored to assure both personal health and public health benefits.

The statement includes a note that an undetectable viral load only prevents HIV transmission -- not the transmission of other STIs or pregnancy -- and that people "having sex with multiple partners or in a non-monogamous relationship ... might consider using condoms to prevent other STIs." It also includes a definition of the word negligible: "so small or unimportant as to not be worth considering; insignificant."

The signers of the new statement? Leading public health officials in New York City, Australia and Canada, but also Myron Cohen from UNC, Jens Lundgren at the University of Copenhagen and, of course, Pietro Vernazza, who is listed in PAC's press release as "author, Swiss Statement 2008, Update 2016."

Kalichman, in an email to, called it "Swiss Statement 2016."

They're not alone.

In September, the directors of all U.S. state-based HIV programs, under the auspices of the National Alliance of State and Territorial AIDS Directors, signed on to the statement, which places condomless sex with someone who has an undetectable viral load in the same negligible risk category as spitting.

Then, at the 2016 National Ryan White Conference on HIV Care and Treatment, no less than the head of the NIH, Carl Dieffenbach, Ph.D., echoed the statement, saying, "Once you begin therapy, with full virologic suppression, you are not capable of transmitting HIV to a sexual partner. ... With successful [antiretroviral therapy], that individual is not infectious."

Even Richard Wolitski, Ph.D., acting director of the Office of HIV/AIDS and Infectious Disease Policy at the U.S. Department of Health and Human Services has praised the new consensus statement.

And the NIH is sending another signal, too, about the role of condoms in the lives of people living with HIV and on suppressive antiretroviral therapy. NIAID's Fauci -- the same man who said in 2008 that the Swiss Statement concerned him -- told that, in retrospect and with the data from HPTN 052, the Swiss Statement "turned out to be rather accurate."

"My major statement to you is that the data we've accumulated from the time the Swiss Statement came out to today, now several years later," he said, "actually confirms and verifies that someone with an undetectable viral load on [antiretroviral therapy] has a very low chance of transmitting HIV to someone else."

When asked whether he would endorse the Swiss Statement, including that people could have sex without condoms if they meet Swiss Statement criteria, Fauci said now it's up to the person living with HIV and his or her partner.

"It depends on how much risk someone is willing to accept," he said. "If people are OK with a very, very low risk that's not zero, they can take that risk. There are also going to be people who recognize that, you know, it's possible to get a blip [of detectable viral load] once in a while and who want that very, very low risk to be as close to zero as possible. Then they can go the extra step and use a condom."

No Regrets

Vernazza stands by the release of the Swiss Statement. Maybe back then, he says, it would have been more accurate to say that we'd learned that people living with HIV and on stable HIV treatment with suppressed viral loads for more than six months "are very unlikely to transmit" HIV, rather than that they "cannot transmit" the virus. But he doesn't regret the controversy -- or starting the discussion. And this year, when the Prevention Access Campaign created a consensus statement saying that the risk of HIV transmission from those described in the Swiss Statement is actually negligible to non-existent, Vernazza came on as one of the first endorsers.

"Perhaps," he said, "the issue would never have gained this importance if I'd phrased it less provocatively."

Heather Boerner is a health care journalist based in San Francisco and author of Positively Negative: Love, Pregnancy and Science's Surprising Victory Over HIV.

Copyright © 2016 Remedy Health Media, LLC. All rights reserved.
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