The Need for Condoms on the HIV Prevention Pill

HIV pre-exposure prophylaxis (PrEP) is a powerful prevention tool. A daily dose of Truvada can reduce the risk of getting HIV by as much as 92%. However, the use of condoms and avoiding high-risk behaviors is still important for men who have sex with men (MSM), serodiscordant couples (one partner has HIV and the other doesn't), and anyone who is at a high enough HIV risk to warrant using PrEP.

Understanding PrEP, Condoms, and Sexual Behavior

Studies have found that preference for condomless sex is a motivating factor that leads couples and individuals to choose PrEP as their primary form of protection.

At least one-third of MSM infections occur within a committed relationship. Even when both partners are HIV-negative, high rates of condomless anal sex, both within and outside the relationship (90% and 34%, respectively), account for high rates of infection.

Other factors contribute to a couple's decision or to an individual's decision to replace condoms with PrEP (as opposed to using them in tandem).

These can include:

• Reduction of HIV-related anxiety
• Perceived control over one’s sexual health
• The desire to have children

But does PrEP necessarily encourage condomless sex? Most research suggests that it doesn’t. In fact, whether within or outside a relationship, sexual behaviors, including sexual risk-taking, were not seen to change significantly in most people who chose to use PrEP.

Instead, PrEP appeared to reinforce risk reduction behaviors in those who recognized themselves to be at high risk. This was particularly true for mixed-status couples, who are more likely to use multiple tools (including condoms and HIV treatment as prevention) to prevent transmitting HIV to the uninfected partner.

PrEP Was Not Created Equal

However, younger people taking PrEP tend to have a low treatment adherence rate and tend to also increase behaviors that could lead to HIV exposure while taking PrEP. Furthermore, high rates of syphilis, gonorrhea, and chlamydia add to the likelihood of HIV, and can potentially negate the benefits of PrEP.

A 2016 study from the Adolescent Medicines Trial Network (ATN) for HIV/AIDS Interventions reported that 90% of MSM aged 18-22 engaged in condomless anal sex while on PrEP, and that the incidence increased the more adherent a person was to therapy. (Adherence was qualified by higher blood concentration of Truvada.)

More concerningly, the rate of drug adherence was seen to decline rapidly in this group—from a high of 56% at week four to only 36% by week 48—during which time the rate of sexually transmitted infections (22%) remained unchanged. Whether risk behaviors would reverse in line with decreasing adherence rates remains unclear.

The Effect of PrEP on Women

Gender also plays a role in the efficacy of PrEP. This treatment has been considered a potential means of self-protection for women who are sexually disempowered, but the impact on prevention is not well documented.

Early research showed that rates of treatment failure were far higher among women on PrEP than they were among men, and that inconsistent dosing played a role. A 2014 study from the University of North Carolina (UNC) suggested that another factor making PrEP less effective in women is the lower concentrations of the drug in vulnerable cervical and vaginal tissues.

The UNC researchers found that the absorption and distribution of Truvada within these cells fell well below those of anal and rectal tissues. Even with uninterrupted daily adherence, only 75% of women were able to have the same level of protection as MSM.

The disparity strongly supports the use of PrEP as a complementary, rather than an alternative tool for HIV prevention in women.

PrEP Failures in Men Who Have Sex With Men

PrEP has never been endorsed as a stand-alone strategy, even among MSM. Other means of protection are often recommended, especially among high-risk individuals—those who engage in group sex, rough sex, or injecting drug use.

One reason is that drug-resistant HIV strains that don't respond to tenofovir and emtricitabine (the two drug agents contained in Truvada) have been identified.

As recently as 2016, epidemiological research from the Centers for Disease Control and Prevention (CDC) concluded the resistance to tenofovir—the primary drug in Truvada—was already pegged at around 20% in North America and Europe and could be as high as 50% in Africa. The authors of the study said that there are several important limitations of their research and suggest that estimates of the prevalence of tenofovir resistance might not be representative in certain high-burden regions. Furthermore, they only included patients with documented treatment failure, and thus were unable to assess overall rates of tenofovir resistance in patients starting first-line treatment.

While there is far less data on global emtricitabine resistance, several animal studies have shown that resistance to tenofovir alone is enough to cause a breakthrough in infections, even with daily adherence to PrEP. 

What This Tells Us

From the public health perspective, the message remains clear: PrEP is recommended as part of a comprehensive HIV prevention strategy, which includes the use of condoms and a reduction in risk behaviors.

Moreover, PrEP is not intended for everyone, but rather for those considered to be at high risk. When used, PrEP should always be taken daily, without interruption, and with regular testing to confirm HIV status and to avoid side effects.

If your partner is HIV-positive, it’s important that you know whether they are being treated for it. More importantly, you need to know whether they have an undetectable viral load.

Most public health officials believe that people who have HIV who are virally suppressed cannot transmit the virus. It is, therefore, reasonable to suggest that when an HIV positive partner uses HIV therapy, and the HIV negative partner uses PrEP, this may provide ample protection against HIV in the absence of condoms—but only if the virus is fully suppressed and if daily adherence to PrEP is assured.

However, it has not been confirmed that complete viral suppression means that there is a 0% chance of getting infected. Only complete sexual abstinence can guarantee that.

To fully self-protect, you need to consider your vulnerability to infection, as well as the infectivity of your sexual partner. If your partner’s status is unknown (and you’re unable or unwilling to discuss this with them), then you should take every precaution to avoid infection, including the use of condoms.