Issue:  Vol. 48 / No. 7 / 15 February 2018

Second PrEP failure reported at HIV prevention confab


Dr. Howard Grossman. Photo: Roger Pebody
Print this Page
Send to a Friend
Share on Facebook
Share on Twitter
Share on MySpace!

A second case of HIV infection with resistant virus while on PrEP was reported this week at the HIV Research for Prevention, or HIVR4P, conference in Chicago. But experts stressed that infection while on PrEP is very rare and it remains a highly effective HIV prevention strategy.

The recently infected man was taking daily Truvada as directed and had protective drug levels in his hair and dried blood samples. However, he became infected with an HIV strain that had developed resistance to multiple antiretrovirals, including those in the Truvada combination pill (tenofovir and emtricitabine).

"Fortunately these resistant viruses are rare," said Dr. Howard Grossman from the Cleveland Clinic in West Palm Beach, Florida, who described the case at an HIVR4P press briefing October 18. He estimated that about 100,000 people in the U.S. have taken PrEP.

Grossman said that the man had repeatedly tested HIV-negative before starting PrEP in January. But when tested again in May, he showed evidence of being infected, although commonly used tests gave mixed results.

The man had an HIV-positive male partner on antiretroviral therapy with undetectable viral load, which is known to reduce the risk of transmission to near zero. But genetic testing showed that the newly infected man's virus was not related to that of his partner. The couple said they'd had threesomes with other men on two occasions, which is thought to be the source of the infection. The newly infected man said he had only had insertive sex during these encounters.

"It is a myth that tops don't get HIV," Grossman said.

Grossman explained that the standard HIV testing algorithm did not pick up the new infection. After seeing confusing results, he sent blood samples to other experts for specialty testing and further analysis, including Dr. Robert Grant from the UCSF Gladstone Institutes. But Grossman acknowledged that community clinics and primary care providers might not have access to these resources.

The newly infected man added two other classes of antiretrovirals to Truvada to build an effective combination regimen, and he was able to reach and maintain an undetectable viral load.


PrEP still highly effective

Researchers and advocates at the conference emphasized that the risk of HIV infection while taking PrEP consistently is very low.

The international iPrEx trial showed that daily Truvada reduced the risk of HIV infection by 92 percent among gay and bisexual men with blood drug levels indicating regular use. In an open-label extension of iPrEx and in several PrEP demonstration projects, none of the men who took Truvada at least four times a week became infected.

Only one other well-documented case of PrEP failure due to drug resistant virus has been reported to date.

At the Conference on Retroviruses and Opportunistic Infections in February, Dr. David Knox from the Maple Leaf Medical Clinic in Toronto reported that a gay man who had been on Truvada PrEP for two years became infected with a strain of HIV that was resistant to both emtricitabine and tenofovir.

"Becoming infected with a virus like this one with so much resistance is rare," Dr. Albert Liu from the San Francisco Department of Public Health told the Bay Area Reporter at the time. "While it's important to know that these cases can happen, PrEP is still a very powerful tool that can help prevent new infections in our community."

Based on the latest report, experts do not suggest changing messages about PrEP.

"I will continue to say that using PrEP is protective against getting HIV and there are no guarantees," Grant told Damon Jacobs, who runs the popular PrEP Facts Facebook page, in a report for "Infection during PrEP use is rare. If infection occurs, it can be treated. In the absence of PrEP, HIV infection is much more common."


Follow The Bay Area Reporter
facebook logo
facebook logo
Newsletter logo
Newsletter logo
ISSUU logo