Pietro Vernazza, MD, on The Scientific Underpinnings of U=U

In 2008, the Swiss Federal Commission on AIDS related issues published the “Swiss Statement,” suggesting that there was strong evidence to support that there is no risk of sexually transmitting HIV when an individual is virally suppressed and on antiretroviral therapy.

Eleven years later, at the Annual Conference on Retroviruses and Opportunistic Infections (CROI 2019), Pietro Vernazza, MD, chief of the infectious disease division at Kantonsspital St. Gallen, in Switzerland, gave a presentation on the scientific underpinnings of Undetectable equals Untransmittable (U=U).

Following the symposia, Dr. Vernazza sat down with Contagion® to discuss the presentation and the concept of U=U.

Contagion®: What should clinicians know about U=U? Are there any misconceptions?

Dr. Vernazza: So, at today's meeting it was very clear that all the evidence that we have is really so solid that somebody who is on a well-conducted therapy will not transmit the virus. So there really are not any questions anymore and because once you have very well conducted treatment there's no risk that you can infect somebody.

Importantly for physicians, if they talk to their patients about U=U or not being infectious, it's important that physicians also clearly demonstrate with their nonverbal communication and also in words that there's no risk, [the patient] does not have to be afraid. Once you have very good treatment that results in suppressed viral load, you're fine it's okay, and it will remain so.

Contagion®: Can you summarize your presentation on the scientific underpinnings of U=U?

Dr. Vernazza: So, in that presentation, I, of course, as a first author of the Swiss Statement, I had to start with a Swiss Statement and discuss what the evidence was that we had in the past when we issued the Swiss Statement, and the evidence was we did not see a single case of transmission from somebody who was on treatment.

Now, this evidence has continued, 11 years later we still do not have a single case of transmission and that is very strong evidence, because now if somebody would see somebody who has transmitted the virus while on treatment this case would have been published — because everybody would like to falsify the Swiss Statement, but it wasn't possible.

And then I summarized all the evidence from prospective studies and if you take all this together, all the prospective studies 052, PARTNERS, OPPOSITES ATTRACT, all these studies found zero risk. And of course, you never know could we be wrong, but when you take everything together we have not detected it. The small risk always remains, but it's so small it's far below 1 in 1000 partner years so that is risk that is far below our normal daily risk. So, you can safely say that there is no risk.

Contagion®: What are some areas of U=U that need to be further explored?

Dr. Vernazza: First, physicians have to understand the that this is really true, and it has changed and we have to believe it, we have to communicate it to our patients to tell them ‘there is no risk, you can be safe about it’ and in that in our communication it's also important that we communicate this clear, not ‘you know maybe,’ — it’s clear there's no risk.

And then I think the next step is that we have to make clear that people outside of this field of people affected by HIV, and physicians, everybody should know other physicians but all the general population needs to know that things have changed and there is no reason why you should be afraid that a person who is HIV positive and on treatment [can transmit the virus], there's no risk. And, that I think is important that finally stigma in the field of HIV and AIDS can be reduced and stigma is still the remaining epidemic.