With advancements in HIV treatment, many people living with HIV can achieve an undetectable viral load. This leads to the very important concept of “Undetectable = Untransmittable”, or U=U, meaning that people living with HIV who achieve and maintain an undetectable viral load have effectively no risk of sexually transmitting HIV to their partners.
This has led many people to wonder – if my partner is living with HIV but has an undetectable viral load, do I still need to take pre-exposure prophylaxis (PrEP) to prevent getting HIV?
What does it mean to have an undetectable viral load?
When someone is living with HIV and takes antiretroviral therapy (ART) as prescribed, the medications work to reduce the amount of virus in their blood, also known as their viral load. With effective treatment, viral load can become very low – so low that tests are unable to detect it. This is called being “undetectable”.
To be considered undetectable, a person’s viral load must be below 200 copies/mL. When maintained over time, this low level greatly prevents the virus from being transmitted to others. Having an undetectable viral load for at least 6 months is the goal for people living with HIV.
HIV is not transmittable if your partner is undetectable
U=U stands for “Undetectable = Untransmittable”. This means that when people living with HIV take their ART as prescribed and maintain an undetectable viral load, they have effectively no risk of passing HIV on to their sexual partners.
This concept has been proven through major scientific studies like HPTN 052 and PARTNER. These studies enrolled thousands of couples where one partner was living with HIV and the other was not, and they tracked the number of new HIV infections that occurred when condoms were not used. The studies found no cases of HIV transmission between partners when the HIV-positive partner had an undetectable viral load.
Based on this evidence, the U.S. Centers for Disease Control and Prevention (CDC) has stated that people living with HIV who maintain an undetectable viral load have “effectively no risk” of sexually transmitting HIV. U=U is now a widely endorsed concept in the HIV prevention field.
Why consider taking PrEP if your partner is undetectable?
Even though the evidence clearly shows that HIV is not transmittable when viral load is undetectable, some people in this situation still consider taking PrEP as an extra precaution. There are a few reasons why:
Wanting added peace of mind
For some people, the U=U concept can be difficult to fully trust, especially if there are any concerns about their partner’s consistency in taking ART or getting regular viral load testing. Taking PrEP can provide added peace of mind.
Concerns that viral load could become detectable
While the goal is for viral load to stay undetectable, things happen in life that could cause it to become detectable again. For example, difficulty getting refills of ART or insurance coverage, side effects that make it hard to take the medications consistently, or other illnesses that inhibit how the ART works. If viral load becomes detectable again, PrEP provides protection.
Window period after starting ART
When someone first starts taking ART, it takes a little time – usually several months – for viral load to drop down to undetectable levels. During this time, known as the window period, viral load is dropping but can still be detectable, meaning some transmission risk exists. Taking PrEP helps close this gap.
PrEP for other relationships
Some people in a relationship with an HIV-positive partner who is undetectable are also not in a mutually monogamous relationship. They may have other partners whose HIV status they do not know. Taking PrEP can help protect against HIV transmission from outside partners.
Why PrEP may not be necessary if partner is undetectable
On the other hand, there are also good reasons why taking PrEP may not provide much additional benefit if your partner living with HIV has an undetectable viral load:
PrEP doesn’t offer more HIV protection
With U=U, your partner already has effectively no risk of transmitting HIV to you through sex as long as their viral load stays undetectable. PrEP does not offer any additional HIV protection in this situation.
Lowers medication side effects
PrEP medication Truvada can sometimes cause side effects like nausea, fatigue, and kidney issues. Not taking unnecessary medication can avoid these side effects.
Reduces costs
PrEP medications, lab tests, and provider visits cost money, even with insurance. If you are at effectively no risk from your partner, avoiding these costs may make sense.
Keeps clinics from getting overloaded
In some areas, PrEP clinics have long waitlists and limited capacity. Not taking resources from overburdened clinics when unneeded allows for those slots to go to others at higher risk.
Examining the evidence on PrEP need if partner is undetectable
Research studies provide some data on how necessary PrEP is when a partner’s viral load is suppressed:
CDC modeling study
A 2015 CDC modeling study found that people in relationships with an undetectable partner gain little additional HIV protection benefit from PrEP. However, they estimated that PrEP could prevent about 10% more HIV infections in this situation.
PARTNER2 study
This study on HIV transmission risk published in 2019 included 783 couples who reported condomless sex when the HIV-positive partner had an undetectable load. 15 new HIV infections occurred, but none were linked to the HIV-positive partner, indicating infections were acquired from outside partners. This underscores that PrEP could offer added protection against other partners.
Opposites Attract study
This 2017 study followed nearly 400 gay couples where one partner was HIV-positive and one was HIV-negative. When the HIV-positive partner was virally suppressed, no HIV infections occurred over 5 years. Only 2 HIV infections happened overall in couples who always used PrEP, showing minimal added protection.
Considering your situation and risk tolerance
The choice of whether to take PrEP or not can be a very personal decision that depends on your specific situation. Here are some questions to think through:
Is your partner consistently taking ART and undetectable?
If your partner is new to ART or has trouble sticking to their medication regimen, PrEP could provide protection during periods when viral load is not fully suppressed.
Are you in a mutually monogamous relationship?
If either you or your partner has other sexual partners, PrEP can prevent HIV acquisition from a partner outside the relationship whose status is unknown.
Are you trying to conceive with your partner?
PrEP could offer added reassurance when trying to get pregnant, since a marginal increase in risk may be more concerning.
How risk tolerant are you?
Your tolerance for risk, feelings about medications, and desired level of HIV reassurance can all play a role. There is no right or wrong level of acceptable risk – this is a decision only you can make.
What are your PrEP access barriers?
Issues like insurance coverage, clinic wait times, and frequency of medical visits may impact if taking PrEP is feasible for your situation.
Ways to reduce need for PrEP while maintaining peace of mind
If you decide PrEP is not necessary but still want added reassurance, there are some options to gain confidence without medication:
Ask your partner to sign an HIV care agreement
This outlines your partner’s commitment to stay in HIV care and maintain an undetectable viral load. It can include agreements around ART adherence, doctor visits, and open communication. This builds trust and accountability.
Have your partner get viral load testing every 3 months
CDC recommends people with HIV get viral load testing every 3-6 months. Testing every 3 months rather than 6 can identify any viral changes sooner.
Consider using condoms
Condoms provide added physical protection and can reassure if viral load has an unexpected increase. Many couples use condoms some of the time but not every time.
Ask your partner’s HIV provider questions
Connecting with your partner’s HIV doctor allows you to ask questions and build confidence in their treatment plan and viral suppression. Consider signing consent forms so their doctor can speak with you.
Get involved in your local HIV community
Connecting with advocates working in HIV prevention and U=U education locally can help build knowledge and trust in the evidence behind undetectable viral loads.
The final decision around PrEP is up to you
There are good arguments both for and against taking PrEP when your partner living with HIV has achieved an undetectable viral load. The right choice comes down to your unique situation and feelings.
If you feel uncertainty, have an open discussion with your partner about your concerns and options. Speaking to an HIV medical or prevention provider for guidance can also help. Educating yourself about the latest research around U=U helps make an informed decision.
Ultimately, assessing your personal risk tolerance and feelings around medication can lead you to the PrEP choice that provides the most peace of mind. Being empowered to make the decision that’s right for you is what’s most important when evaluating your HIV prevention options.
The takeaway on PrEP when your partner has undetectable HIV
When someone living with HIV takes ART as prescribed and maintains an undetectable viral load, they cannot transmit HIV through sex. However, some people in this situation choose to take PrEP for added peace of mind.
The decision about whether to take PrEP depends on factors like relationship dynamics, sexual practices, risk tolerance, and personal feelings about medication. Speaking to your partner and your healthcare provider can help inform the choice right for you.
People in relationships with undetectable partners gain substantial HIV protection from ART alone. While adding PrEP provides limited additional benefit, some may decide this extra reassurance is right for their situation. Being empowered to make the decision that meets your prevention needs and helps you feel fully safe in your relationship is the most important outcome.
| Reasons Some May Want PrEP with an Undetectable Partner | Reasons PrEP May Not Be Necessary with an Undetectable Partner |
|---|---|
| Desire added peace of mind around transmission risk | PrEP doesn’t offer more HIV protection if partner stays undetectable |
| Concern viral load could become detectable again | Avoid side effects from unnecessary medication |
| Protection during ART start window period | Reduce costs of PrEP medications, tests and doctor visits |
| PrEP to prevent HIV from other partners | Save scarce PrEP resources for those at higher risk |
Conclusion
While HIV is not transmittable when viral load is durably suppressed, some people may want extra reassurance from PrEP. Consider your personal situation, risk tolerance, relationship practices, and feelings about medication when deciding if PrEP is right for you with an undetectable partner. Empower yourself to choose the HIV prevention approach that meets your needs.