No new HIV infections seen among Kaiser PrEP users

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No new HIV infections have occurred among more than 500 users of the Kaiser Permanente healthcare provider system in San Francisco in members using pre-exposure prophylaxis – better known as PrEP.

However, condom use appears to be declining among a subset of gay men, according to a small survey presented at a December 1 forum commemorating World AIDS Day.

"PrEP is provided for the purpose of preventing HIV infections, and we're seeing that hold true," said Bradley Hare, Kaiser's San Francisco director of HIV care and prevention.


sexually transmitted diseases (STDs)

Although HIV can be sexually transmitted, the term is most often used to refer to chlamydia, gonorrhoea, syphilis, herpes, scabies, trichomonas vaginalis, etc.

control group

A group of participants in a trial who receive standard treatment, or no treatment at all, rather than the experimental treatment which is being tested. Also known as a control arm.

Food and Drug Administration (FDA)

Regulatory agency that evaluates and approves medicines and medical devices for safety and efficacy in the United States. The FDA regulates over-the-counter and prescription drugs, including generic drugs. The European Medicines Agency performs a similar role in the European Union.


A sexually transmitted infection caused by the bacterium Treponema pallidum. Transmission can occur by direct contact with a syphilis sore during vaginal, anal, or oral sex. Sores may be found around the penis, vagina, or anus, or in the rectum, on the lips, or in the mouth, but syphilis is often asymptomatic. It can spread from an infected mother to her unborn baby.


Chlamydia is a common sexually transmitted infection, caused by bacteria called Chlamydia trachomatis. Women can get chlamydia in the cervix, rectum, or throat. Men can get chlamydia in the urethra (inside the penis), rectum, or throat. Chlamydia is treated with antibiotics.

Hare described preliminary findings from a survey of Kaiser members who started taking Gilead Sciences' Truvada (tenofovir/emtricitabine) combination pill to prevent HIV.

The US Food and Drug Administration (FDA) approved Truvada for PrEP in July 2012, and this past May, the US Centers for Disease Control and Prevention (CDC) recommended that people at substantial risk for HIV infection should consider PrEP, basing its recommendations on findings from the iPrEx trial and others.

The Kaiser survey was only recently initiated and so far has received responses from approximately 90 members – less than 20% of PrEP recipients – mostly men who have sex with men. The survey is intended to help Kaiser providers learn more about their patients taking PrEP in an effort to provide better clinical care, Hare said.

Such preliminary results presented at an informal forum normally would not be major news. But the AIDS Healthcare Foundation – which has waged a media campaign against PrEP – issued a press release on December 8 calling attention to an article in the San Francisco Business Times highlighting one number from Hare's presentation: 45% of survey respondents reported using condoms less often since they started PrEP.

"This Kaiser study confirms the fears of organizations like AHF that have expressed caution and skepticism about the wisdom of the community’s wholesale embrace – as well as the CDC’s recommendation – of the widespread scale up of PrEP," stated AHF president Michael Weinstein.

"This study should serve as a warning and may one day be seen as the canary in the coal mine of unintended – but predictable – consequences of a poorly thought out public health strategy." 

Explaining the survey findings in more detail, Hare said that among the 90 people who chose to answer the survey – a group that may not be representative of Kaiser's PrEP users overall – half said their condom use had remained the same, 45% said it had decreased, and 5% said it had increased since they went on PrEP.

Hare emphasised that they do not have baseline data about how often respondents used condoms before starting PrEP, and there is no control group of men not using PrEP for comparison. However, the fact that the men chose to go on PrEP suggests they likely were already having sex without condoms at least some of the time.

"We don’t know if we took [condom use] from 100% to zero, or from 50% to 40%," Hare said. "With the extra protection provided by PrEP, some may have decided to forego condoms" – including people in monogamous relationships with HIV-positive partners, he suggested.

The survey did ask about changes in the number of sexual partners, and found that this did not increase. "It's not the case that people are having a lot of unprotected sex with a lot of new partners" after starting PrEP, Hare said.

PrEP clinical trials generally have not seen evidence of so-called "risk compensation" – engaging in more risky behaviour or reducing use of other prevention methods. But anecdotal reports in the gay community suggest that many men find dispensing with condoms to be one of the major benefits of PrEP.

The important question concerning HIV is not so much whether they are using condoms less, but whether they are protected from HIV better or worse than they were before they started PrEP. But as Weinstein noted, PrEP critics fear that a reduction in condom use could lead to a rise in other sexually transmitted diseases (STDs).

"We are seeing a high numbers of STDs in people on PrEP," Hare acknowledged, but again he stressed that there is no control group of people not taking PrEP to use for comparison.

These STDs include the "usual suspects" syphilis, gonorrhoea, and chlamydia, he said, but Kaiser providers have also seen two cases of acute hepatitis C in HIV-negative gay men who were not injection drug users. Sexually transmitted hepatitis C has been reported among HIV-positive men over the past decade and a half, but it has been thought to be rare among HIV-negative men.

While concern about STDs is well founded, the goal of PrEP is to prevent HIV, Hare emphasised.

"We've seen zero cases of HIV among more than 500 guys on PrEP," he said. "Behaviour and STDs are important things to watch to be able to prescribe it responsibly, but PrEP is prescribed to prevent HIV, and it's working."

How many are on PrEP?

Another number from Hare's presentation stands out. The total number of people receiving PrEP at Kaiser is now just over 500. When Kaiser physician Jonathan Volk gave an overview of PrEP users at a San Francisco Department of Public Health community forum this past September, the number stood at just over 300 through July 2014, indicating a rapid rise in recent months.

However, Volk and Hare noted that about one-third of people who are referred to the programme decide not to start PrEP for a variety of reasons, including cost and concern about side-effects – a worry generally not supported by evidence from clinical trials, but often cited as a concern in qualitative studies: it was the most common reason participants in iPrEx gave for not wishing to continue into the open-label extension (iPrEx OLE) of the study.

Speaking at a San Francisco Board of Supervisors hearing in September, iPrEx principal investigator Robert Grant estimated that approximately 800 people in San Francisco were using PrEP, and that Kaiser is the largest PrEP programme in the US.

Nationwide, a Gilead analysis of prescription data from 55% of US pharmacies, presented at the HIV Drug Therapy conference last month in Glasgow, found that a total of 3253 people had been prescribed PrEP since January 2012 – including 880 prescriptions during the last quarter of 2013 and the first quarter of 2014 alone. These totals do not include people accessing PrEP through Medicaid, clinical trials, or demonstration projects.

Hare expects that the surge in interest in PrEP at Kaiser is likely to continue. "By the time we talk again, it will probably be 600 people," he predicted.