PrEP’s effectiveness at preventing HIV infection is directly linked to how adherent someone is. Only a handful of PrEP users demonstrated to be taking PrEP daily as prescribed have ever been infected with HIV (and most of those cases were likely due to a very rare scenario wherein the strain of HIV they were infected with was resistant to the medications present in PrEP).
However, the more doses an individual misses, the less benefit PrEP provides. For example, in the iPrEX OLE trial there was a significant decrease in HIV risk reduction amongst those who only took 2-3 pills per week when compared to those who took four or more pills per week. The effectiveness decreased even further for those who took less than 2 pills per week.
Fortunately, demonstration projects and real-word PrEP data have demonstrated a high level of adherence by those committed to taking PrEP. Additionally, specialized health clinics with a large number of patients taking PrEP have reported no HIV infections amongst their PrEP patients despite a reasonably high rate of other STIs, reaffirming both the effectiveness of PrEP as an HIV prevention tool and the likely high rate of adherence demonstrated by those taking PrEP.
If an individual faces challenges adhering to their medication, a healthcare provider should help them identify strategies which can make adherence easier for them. Conversely, if taking a pill once a day is still a challenge for someone you might want to look at the following options:
- Choosing another HIV prevention option: If someone is relying on PrEP as their main source of HIV prevention but are not taking it as prescribed, it is unlikely to be effective and could actually provide them with a false sense of security – making them feel protected when they’re not. If someone can’t demonstrate sufficient adherence to PrEP, other HIV prevention options should be discussed with them.
- Intermittent PrEP Use: Some research has demonstrated that PrEP can also be effective at preventing HIV infection when taken intermittently or “on-demand.” Although some individuals are choosing to take PrEP this way, current guidelines still support the daily use of PrEP, recognizing that more research may be required to fully understand the various nuances of intermittent PrEP use. That said, intermittent PrEP use might make sense for someone who is having difficulty taking PrEP daily or whose lifestyle might be better suited to intermittent PrEP use. The Canadian PrEP/nPEP Guidelines speak to intermittent PrEP use here.
Ongoing Monitoring & Follow-Up
While on PrEP, individuals should be engaged in ongoing discussion relating to their overall sexual health, inclusive of risk-reduction counselling, adherence support, and support or referrals related to existing psychosocial or syndemic conditions. This comprehensive, ongoing support is important for a few reasons:
- To ensure a patient is receiving sufficient support related to any underlying issues that might affect their vulnerability to HIV and STIs (and the effective implementation of related prevention interventions)
- To ensure they have sufficient information to prevent STI infection (as PrEP only protects against HIV)
- To determine if they require additional support related to medication adherence
- To determine if PrEP remains a suitable HIV prevention option for them.
In addition to this, individuals should be screened at varying points while on PrEP (30 days after they start, every three months, and yearly) to make sure they remain HIV-negative, are diagnosed and treated for STIs, and that the medication isn’t having any unintended impacts on their health. Renewal of prescription is often contingent on individuals completing required screenings.
Although some providers familiar with HIV and PrEP might choose to make some independent adjustments, the screening schedule recommended by the Canadian PrEP/nPEP Guidelines is as follows:
There might come a time when someone determines that PrEP isn’t right for them anymore. Before the person stops PrEP they should be counseled on the following:
- PrEP isn’t always easy to access. If it initially took the individual a while to obtain a prescription and subsequent coverage, if they stop and then decide to go back on PrEP in the future, they might have to repeat some or all of that process again.
- Will the circumstances related to stopping PrEP remain static for a while or could they change in a month or two, leading the person to decide to start PrEP again? If things are prone to fast change, the person should be encouraged to wait a while before stopping PrEP.
- The Canadian PrEP/nPEP Guidelines recommend that an individual on PrEP continue to take PrEP for up to 28 days after their last potential exposure to HIV.
PrEP isn’t for everybody. Some people aren’t great candidates for PrEP to begin with. Some people might only benefit from PrEP for a short period of their life, stopping when circumstances change. And others would likely benefit from PrEP for a longer period – perhaps for their entire life.
There’s nothing wrong with an individual reviewing their sexual health practices and determining that what worked for them a month or a year ago concerning HIV prevention is no longer the best option for them now. What is key is that they make this decision within the context of a comprehensive sexual health discussion with a provider they trust. And if an individual does decide to stop PrEP, they should be engaged in discussion about what other HIV prevention options they can use in PrEP’s absence.