Table of ContentsView AllTable of ContentsWho PrEP Is ForPrEP MedicationsReal-World EfficacyMultiple Sex Partners
Table of ContentsView All
View All
Table of Contents
Who PrEP Is For
PrEP Medications
Real-World Efficacy
Multiple Sex Partners
Pre-exposure prophylaxis (PrEP)medications Truvada and Descovy are taken daily to preventhuman immunodeficiency virus (HIV)inHIV-negativepeople who are considered at high risk for infection.
Justin Sullivan / Getty Images News / Getty Images
This article will explore exactly who PrEP is intended for, each PrEP medication, and factors that may support or reduce their effectiveness.
Anyone can get HIV. Your sex, age, sexual orientation, race, and ethnicity do not independently factor into your risk.
PrEP is for those considered to be at ahighrisk of HIV.
Reasons that put you at high risk include:
The Need for Condoms on PrEP, the HIV Prevention Pill
Both are prescription combination medications taken in a once-daily tablet:
Recap
If your doctor determines you are at high risk, Truvada or Descovy may be recommended.
Real-World Efficacy of PrEP
Some studies among high-risk gay men have reported no infections among those fully adhered to therapy.Among gay men considered the highest level of risk, the use of PrEP was associated with an estimated 86% protective benefit over counterparts who don’t use PrEP.
These results are promising but may not translate to real-world scenarios where numerous factors, including behaviors or rare strains of the virus, may reduce the efficacy of PrEP on an individual level.
The main factors that can significantly reduce the efficacy of PrEP include:
It takes longer to establish an adequate level of protective enzymes in vaginal tissues than in anal and rectal tissue.
PrEP-Resistant HIV
It was widely reported in 2016 that a man taking the HIV prevention drug Truvada contracted the virus despite being fully adherent to the once-daily drug regimen.
The news raised serious concerns among some as to how effective the strategy actually is at ensuring that an HIV-negative person remains uninfected.
In their report, investigators with the Maple Leaf Medical Clinic (MLMC) in Canada confirmed that a 43-year-old gay man had tested positive for HIV while on Truvada. A review of both pharmacy records and the person’s blood tests that measure drug concentrations showed that drug was taken as prescribed.
Genetic testing eventually revealed that the man had acquired a rare mutated strain of HIV that was resistant to the two individual drug agents that comprise Truvada. This effectively cancelled out the drug’s protective benefit.
A 2019 study in the journalDrugslooked at drug resistance found four additional case reports of people acquiring HIV while taking PrEP consistently. Three of those four people also had strains of HIV that were resistant to both drug agents.
In one case, researchers found the person had wild-type HIV, which means there were no HIV-resistant mutations of any sort. (Most people are initially infected with wild-type HIV, or HIV in its natural state.)
PrEP-resistant HIV is still considered rare. For example, in 2018, University of Washington researchers did thousands of genetic sequence tests. They estimated that between 0.4% and 0.6% of the 6,798 people living with HIV in Kings County, which includes Seattle, had both a detectibleviral load(HIV found in blood) and a strain of HIV resistant to tenofovir and emtricitabine.
Among people who became infected despite taking tenofovir-containing anti-retroviral regimens, studies suggest tenofovir resistance runs anywhere from 20% (in Europe) to 57% (in Africa), according to a 2016 report from the TenoRes Study Group.In cases like this, the emtricitabine component in PrEP may not be enough to prevent infection.
It’s possible that the effectiveness of PrEP in some populations may be far lower than in others, but more research is needed.
RecapPrEP reaches maximum effectiveness after seven days for anal sex and 21 days for vaginal sex or injection-drug use. Skipping doses or not using additional protective measures until you reach these points makes PrEP much less effective.There are rare strains of HIV that are resistant to PrEP, though this is rare.
PrEP reaches maximum effectiveness after seven days for anal sex and 21 days for vaginal sex or injection-drug use. Skipping doses or not using additional protective measures until you reach these points makes PrEP much less effective.There are rare strains of HIV that are resistant to PrEP, though this is rare.
PrEP reaches maximum effectiveness after seven days for anal sex and 21 days for vaginal sex or injection-drug use. Skipping doses or not using additional protective measures until you reach these points makes PrEP much less effective.
There are rare strains of HIV that are resistant to PrEP, though this is rare.
PrEP and Multiple Sex Partners
While inconsistent condom use and multiple sex partners, for instance, are known to increase the risk of HIV infection, they might not reduce the effectiveness of PrEP in high-risk individuals.
However, this is not proven and more research is needed.
The case of the person who contracted a wild-type HIV while on PrEP was part of a European PrEP study. The man took the medication as prescribed, which was confirmed through blood tests.
He reported over 90 sex partners and over 100 acts of condomless anal sex during the 12-week trial. While on PrEP, the man was diagnosed twice with rectalgonorrheaand once with rectal chlamydia.
If so, these still-unidentified factors may place others at risk. Until researchers know more, safer sex practices, such as using condoms, should be adhered to if only to provide an additional layer of protection.
This added protection is particularly important if you don’t know whether or not your partners were tested for HIV, or if they have HIV but you’re unsure if they’re being treated with medication.
HIV drugs can reduce viral load, which is the amount of HIV in their blood. A high viral load increases the likelihood of spreading HIV.
In addition, PrEP does not protect you against other types of sexually transmitted infections.
RecapPrEP still cannot be considered a “magic bullet” that somehow negates the benefits of other forms of protection, such as condoms. It is important that you continue to practice safer sex while taking PrEP.
PrEP still cannot be considered a “magic bullet” that somehow negates the benefits of other forms of protection, such as condoms. It is important that you continue to practice safer sex while taking PrEP.
Summary
There are rare strains of HIV virus with mutations that make it resistant to PrEP. There may be other factors that also lower effectiveness. Additional protective measures, such as using condoms, can support PrEP and reduce risk of HIV.
What Is PEP for HIV?
12 SourcesVerywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read oureditorial processto learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.HIV.gov.Pre-exposure prophylaxis.HIV.gov.Who is at risk for HIV?Centers for Disease Control and Prevention.Preventing HIV with PrEP.Buchbinder SP.Maximizing the benefits of HIV preexposure prophylaxis.Top Antivir Med. 2018;25(4):138-142.McCormack S, Dunn DT, et al.Pre-exposure prophylaxis to prevent the acquisition of HIV-1 infection (PROUD): effectiveness results from the pilot phase of a pragmatic open-label randomised trial.Lancet. 2016;387(10013):53-60. doi:10.1016/S0140-6736(15)00056-2Knox DC, Anderson PL, Harrigan PR, Tan DHS.Multidrug-resistant hiv-1 infection despite preexposure prophylaxis.N Engl J Med. 2017;376(5):501-502. doi:10.1056/NEJMc1611639Gibas KM, van den Berg P, Powell VE, Krakower DS.Drug resistance during HIV pre-exposure prophylaxis.Drugs. 2019;79(6):609-619. doi:10.1007/s40265-019-01108-x25th Conference on Retroviruses and Opportunistic Infections.A public health approach to viremic individuals with PrEP-resistant virus.The TenoRes Study Group.Global epidemiology of drug resistance after failure of WHO recommended first-line regimens for adult HIV-1 infection: a multicentre retrospective cohort study.Lancet Infect Dis.2016;16(5):565-575. doi:10.1016/S1473-3099(15)00536-8Centers for Disease Control and Prevention.Effectiveness of prevention strategies to reduce the risk of acquiring or transmitting HIV.Hoornenborg E, Prins M, Achterbergh RCA, et al.Acquisition of wild-type HIV-1 infection in a patient on pre-exposure prophylaxis with high intracellular concentrations of tenofovir diphosphate: a case report.The Lancet HIV. 2017;4(11):e522-e528. doi:10.1016/S2352-3018(17)30132-7Centers for Disease Control and Prevention.How HIV spreads.
12 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read oureditorial processto learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.HIV.gov.Pre-exposure prophylaxis.HIV.gov.Who is at risk for HIV?Centers for Disease Control and Prevention.Preventing HIV with PrEP.Buchbinder SP.Maximizing the benefits of HIV preexposure prophylaxis.Top Antivir Med. 2018;25(4):138-142.McCormack S, Dunn DT, et al.Pre-exposure prophylaxis to prevent the acquisition of HIV-1 infection (PROUD): effectiveness results from the pilot phase of a pragmatic open-label randomised trial.Lancet. 2016;387(10013):53-60. doi:10.1016/S0140-6736(15)00056-2Knox DC, Anderson PL, Harrigan PR, Tan DHS.Multidrug-resistant hiv-1 infection despite preexposure prophylaxis.N Engl J Med. 2017;376(5):501-502. doi:10.1056/NEJMc1611639Gibas KM, van den Berg P, Powell VE, Krakower DS.Drug resistance during HIV pre-exposure prophylaxis.Drugs. 2019;79(6):609-619. doi:10.1007/s40265-019-01108-x25th Conference on Retroviruses and Opportunistic Infections.A public health approach to viremic individuals with PrEP-resistant virus.The TenoRes Study Group.Global epidemiology of drug resistance after failure of WHO recommended first-line regimens for adult HIV-1 infection: a multicentre retrospective cohort study.Lancet Infect Dis.2016;16(5):565-575. doi:10.1016/S1473-3099(15)00536-8Centers for Disease Control and Prevention.Effectiveness of prevention strategies to reduce the risk of acquiring or transmitting HIV.Hoornenborg E, Prins M, Achterbergh RCA, et al.Acquisition of wild-type HIV-1 infection in a patient on pre-exposure prophylaxis with high intracellular concentrations of tenofovir diphosphate: a case report.The Lancet HIV. 2017;4(11):e522-e528. doi:10.1016/S2352-3018(17)30132-7Centers for Disease Control and Prevention.How HIV spreads.
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read oureditorial processto learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
HIV.gov.Pre-exposure prophylaxis.HIV.gov.Who is at risk for HIV?Centers for Disease Control and Prevention.Preventing HIV with PrEP.Buchbinder SP.Maximizing the benefits of HIV preexposure prophylaxis.Top Antivir Med. 2018;25(4):138-142.McCormack S, Dunn DT, et al.Pre-exposure prophylaxis to prevent the acquisition of HIV-1 infection (PROUD): effectiveness results from the pilot phase of a pragmatic open-label randomised trial.Lancet. 2016;387(10013):53-60. doi:10.1016/S0140-6736(15)00056-2Knox DC, Anderson PL, Harrigan PR, Tan DHS.Multidrug-resistant hiv-1 infection despite preexposure prophylaxis.N Engl J Med. 2017;376(5):501-502. doi:10.1056/NEJMc1611639Gibas KM, van den Berg P, Powell VE, Krakower DS.Drug resistance during HIV pre-exposure prophylaxis.Drugs. 2019;79(6):609-619. doi:10.1007/s40265-019-01108-x25th Conference on Retroviruses and Opportunistic Infections.A public health approach to viremic individuals with PrEP-resistant virus.The TenoRes Study Group.Global epidemiology of drug resistance after failure of WHO recommended first-line regimens for adult HIV-1 infection: a multicentre retrospective cohort study.Lancet Infect Dis.2016;16(5):565-575. doi:10.1016/S1473-3099(15)00536-8Centers for Disease Control and Prevention.Effectiveness of prevention strategies to reduce the risk of acquiring or transmitting HIV.Hoornenborg E, Prins M, Achterbergh RCA, et al.Acquisition of wild-type HIV-1 infection in a patient on pre-exposure prophylaxis with high intracellular concentrations of tenofovir diphosphate: a case report.The Lancet HIV. 2017;4(11):e522-e528. doi:10.1016/S2352-3018(17)30132-7Centers for Disease Control and Prevention.How HIV spreads.
HIV.gov.Pre-exposure prophylaxis.
HIV.gov.Who is at risk for HIV?
Centers for Disease Control and Prevention.Preventing HIV with PrEP.
Buchbinder SP.Maximizing the benefits of HIV preexposure prophylaxis.Top Antivir Med. 2018;25(4):138-142.
McCormack S, Dunn DT, et al.Pre-exposure prophylaxis to prevent the acquisition of HIV-1 infection (PROUD): effectiveness results from the pilot phase of a pragmatic open-label randomised trial.Lancet. 2016;387(10013):53-60. doi:10.1016/S0140-6736(15)00056-2
Knox DC, Anderson PL, Harrigan PR, Tan DHS.Multidrug-resistant hiv-1 infection despite preexposure prophylaxis.N Engl J Med. 2017;376(5):501-502. doi:10.1056/NEJMc1611639
Gibas KM, van den Berg P, Powell VE, Krakower DS.Drug resistance during HIV pre-exposure prophylaxis.Drugs. 2019;79(6):609-619. doi:10.1007/s40265-019-01108-x
25th Conference on Retroviruses and Opportunistic Infections.A public health approach to viremic individuals with PrEP-resistant virus.
The TenoRes Study Group.Global epidemiology of drug resistance after failure of WHO recommended first-line regimens for adult HIV-1 infection: a multicentre retrospective cohort study.Lancet Infect Dis.2016;16(5):565-575. doi:10.1016/S1473-3099(15)00536-8
Centers for Disease Control and Prevention.Effectiveness of prevention strategies to reduce the risk of acquiring or transmitting HIV.
Hoornenborg E, Prins M, Achterbergh RCA, et al.Acquisition of wild-type HIV-1 infection in a patient on pre-exposure prophylaxis with high intracellular concentrations of tenofovir diphosphate: a case report.The Lancet HIV. 2017;4(11):e522-e528. doi:10.1016/S2352-3018(17)30132-7
Centers for Disease Control and Prevention.How HIV spreads.
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