Pre-Exposure Chemoprophylaxis (PREP) as an HIV Prevention Strategy

Recommendations for reducing the risk of viral transmission during fertility treatment with the use of autologous gametes: a committee opinion

Sexually transmitted infections are of major concern to reproductive specialists. Heading the list are human immunodeficiency virus types 1 and 2 and hepatitis B and C viruses. These pathogens, which may cause incurable chronic infections, can be transmitted through assisted reproductive technologies and from infected mothers to the fetus or newborn. This document replaces the document of the same name, last published in 2020.

Recommendations for reducing the risk of viral transmission during fertility treatment with the use of autologous gametes: a committee opinion

Sexually transmitted infections are of major concern to reproductive specialists. Heading the list are human immunodeficiency virus types 1 and 2 and hepatitis B and C viruses. These pathogens, which may cause incurable chronic infections, can be transmitted through assisted reproductive technologies and from infected mothers to the fetus or newborn. This document replaces the document of the same name last published in 2013 (Fertil Steril 2013;99:340-6).

Achieving 90-90-90 Human Immunodeficiency Virus (HIV) Targets Will Not Be Enough to Achieve the HIV Incidence Reduction Target in Australia

Background

We estimated the human immunodeficiency virus (HIV) incidence reduction in Australia that would correspond to achieving the United Nations Program on HIV and AIDS (UNAIDS) 90-90-90 targets by 2020 and extended targets of 95-95-95 by 2030. This was done in combination with various scale-ups of HIV testing, primary prevention, and preexposure prophylaxis (PrEP) among high-risk men who have sex with men (MSM). These projections were evaluated against the target of achieving a 90% reduction in HIV incidence by 2030 compared with 2010 levels.

Methods

A mathematical model.

Results

Achieving 90-90-90 by 2020 was estimated to reduce incidence by 10% from 2010 levels. Achieving 95-95-95 by 2030 was estimated to reduce incidence by 17% from 2010 levels, with the first "95" being achievable by testing low- and high-risk MSM 2 and 4 times per year, respectively. This was improved to a 34% reduction by including a 5-year scale-up of PrEP to 30% coverage among high-risk MSM and to 45% by also increasing MSM condom use from 42% to 60%. However, even with 95-95-95, 2 and 4 tests per year for low- and high-risk MSM, 100% high-risk MSM PrEP coverage, and 100% MSM condom use, only an 80% reduction in incidence was possible by 2030.

Conclusions

Many countries, particularly those with low HIV prevalence, will struggle to achieve a 90% reduction in HIV incidence by 2030, even if UNAIDS targets are met. Most will require substantially higher levels of prevention coverage and higher testing frequencies to reach this target.

Pre-exposure prophylaxis: a useful tool to prevent human immunodeficiency virus infection?

The aim of preventive measures against human immunodeficiency virus (HIV) is to reduce the incidence of HIV infection in the general population and in high-risk groups, such as men having sex with men (MSM), and to reduce the risk that a given individual will contract or spread the virus. Male and female condoms, post-exposure prophylaxis and circumcision are preventive methods currently recognized or promoted worldwide. Although modest success has been reported in a phase-III vaccine trial, other methods are being evaluated, such as vaginal and rectal microbicides, and pre-exposure prophylaxis (PrEP). Herein, we discuss results from prevention trials, especially those focusing on PrEP and particularly on recent results from 'on-demand' PrEP regimens. The efficacy of PrEP (rates of 0%-86%) is strongly correlated with adherence and plasma concentrations of antiretrovirals. Adverse events are rare. Selection of emtricitabine-resistant strains is mainly reported in individuals with an undiagnosed HIV infection using PrEP. PrEP is now strongly recommended in WHO prevention programmes for individuals at substantial risk for HIV with a view to controlling this epidemic by 2030.

PrEP: A case study

PURPOSE

The purpose of this case study is to present information and raise awareness about the provision of pre-exposure prophylaxis (PrEP) to those individuals who are at risk for HIV infection.

DATA SOURCES

PubMed, CINAHL, government websites, press releases, and the author's clinical experiences.

CONCLUSIONS

PrEP is the latest tool available for HIV prevention that has been approved by the FDA. It involves taking the HIV medication TDF/FTC on a daily basis. Documented side effects are minimal but renal monitoring is recommended because of possible kidney damage. PrEP may provide as much as 90% protection against HIV infection, but this is dependent upon patient compliance.

IMPLICATIONS FOR PRACTICE

Nurse practitioners are in an ideal position to be the gatekeepers for information and access to PrEP. However, this requires that they engage in thorough risk assessments with their patients. This includes both a comprehensive sexual history and drug use history. The case study demonstrates the importance of intervention in and recognition of high-risk stigmatized populations such as transgender individuals and that prompt action may prevent future HIV infections.

Configuring the users of new HIV-prevention technologies: the case of HIV pre-exposure prophylaxis

HIV pre-exposure prophylaxis (PrEP) is a prevention technology that involves prescribing antiretroviral drugs to HIV-negative people to protect them from infection. This paper considers how the development of the technology has necessitated the parallel configuration of its users, and how this process has affected the perception and uptake of the technology. In designing a technology, potential users are typically defined, enabled and constrained, partly to create a target population (or market) for the technology, but also to reassure people that it can be used safely and effectively. This process may or may not be helpful for the uptake and use of the technology. Published research on PrEP indicates that while the technology was under trial, the primary focus was on the 'at-risk' subject in need of PrEP, with little or no consideration of the other qualities necessary for successful use. Post-trial accounts of PrEP have begun to outline desirable qualities of successful PrEP use, such as caution, compliance and being organised. It appears that the PrEP user was only partially configured during the technology's development, and the initial focus on risk has done little to counter fears of the technology, which may partially account for its slow uptake.

Knowledge of pre-exposure prophylaxis (PrEP) for HIV prevention among men who have sex with men in Denver, Colorado

As part of the National HIV Behavioral Surveillance System among men who have sex with men (MSM) in Denver, Colorado, we assessed knowledge of pre-exposure prophylaxis (PrEP); willingness to use PrEP; and potential changes in risk behaviors among HIV-negative participants reporting sexual activity with a male partner in the preceding 12 months. We examined knowledge of PrEP before (2008) and after (2011) results of the iPrEx trial were available. Of the 425 participants in the 2008 sample, 91 (21 %) were aware of PrEP compared to 131 (28 %) of the 461 participants in the 2011 sample (adjusted prevalence ratio: 1.43, 95 % confidence interval: 1.18, 1.72). Despite the increase in 2011, few MSM in Denver were aware of PrEP. Educating high-risk MSM about the potential utility of PrEP as an adjunct to other effective prevention methods is needed when considering the addition of PrEP to the HIV prevention arsenal.

Evaluation of PD 404,182 as an anti-HIV and anti-herpes simplex virus microbicide

PD 404,182 (PD) is a synthetic compound that was found to compromise HIV integrity via interaction with a nonenvelope protein viral structural component (A. M. Chamoun et al., Antimicrob. Agents Chemother. 56:672-681, 2012). The present study evaluates the potential of PD as an anti-HIV microbicide and establishes PD's virucidal activity toward another pathogen, herpes simplex virus (HSV). We show that the anti-HIV-1 50% inhibitory concentration (IC50) of PD, when diluted in seminal plasma, is ∼1 μM, similar to the IC50 determined in cell culture growth medium, and that PD retains full anti-HIV-1 activity after incubation in cervical fluid at 37°C for at least 24 h. In addition, PD is nontoxic toward vaginal commensal Lactobacillus species (50% cytotoxic concentration [CC50], >300 μM), freshly activated human peripheral blood mononuclear cells (CC50, ∼200 μM), and primary CD4(+) T cells, macrophages, and dendritic cells (CC50, >300 μM). PD also exhibited high stability in pH-adjusted Dulbecco's phosphate-buffered saline with little to no activity loss after 8 weeks at pH 4 and 42°C, indicating suitability for formulation for transportation and storage in developing countries. Finally, for the first time, we show that PD inactivates herpes simplex virus 1 (HSV-1) and HSV-2 at submicromolar concentrations. Due to the prevalence of HSV infection, the ability of PD to inactivate HSV may provide an additional incentive for use as a microbicide. The ability of PD to inactivate both HIV-1 and HSV, combined with its low toxicity and high stability, warrants additional studies for the evaluation of PD's microbicidal candidacy in animals and humans.

Novel intravaginal nanomedicine for the targeted delivery of saquinavir to CD4+ immune cells

The goal of this study was to develop and characterize an intravaginal nanomedicine for the active targeted delivery of saquinavir (SQV) to CD4(+) immune cells as a potential strategy to prevent or reduce HIV infection. The nanomedicine was formulated into a vaginal gel to provide ease in self-administration and to enhance retention within the vaginal tract. SQV-encapsulated nanoparticles (SQV-NPs) were prepared from poly(lactic-co-glycolic acid) (PLGA) and conjugated to antihuman anti-CD4 antibody. Antibody-conjugated SQV-NPs (Ab-SQV-NPs) had an encapsulation efficiency (EE%) of 74.4% + 3.7% and an antibody conjugation efficiency (ACE%) of 80.95% + 1.10%. Over 50% of total loaded SQV was released from NPs over 3 days. NPs were rapidly taken up by Sup-T1 cells, with more than a twofold increase in the intracellular levels of SQV when delivered by Ab-SQV-NPs in comparison to controls 1 hour post-treatment. No cytotoxicity was observed when vaginal epithelial cells were treated for 24 hours with drug-free Ab-NPs (1,000 μg/mL), 1% HEC placebo gel (200 mg/mL), or 1% HEC gel loaded with drug-free Ab-NPs (5 mg NPs/g gel, 200 mg/mL of gel mixture). Overall, we described an intravaginal nanomedicine that is nontoxic and can specifically deliver SQV into CD4(+) immune cells. This platform may demonstrate potential utility in its application as postexposure prophylaxis for the treatment or reduction of HIV infection, but further studies are required.

The promise of pre-exposure prophylaxis with antiretroviral drugs to prevent HIV transmission: a review

PURPOSE OF REVIEW

Public health experts are wrestling with how to translate recent scientific findings from pre-exposure prophylaxis (PrEP) effectiveness trials into real-world programmes. This review summarizes clinical trial findings on oral and topical PrEP, discusses how decision-makers can evaluate the place of PrEP within combination prevention and highlights anticipated developments that could be important in future HIV-prevention strategies.

RECENT FINDINGS

PrEP taken daily as oral tablets to create systemic protection has been found to be effective in the Pre-Exposure Prophylaxis Initiative (iPrEx), Partners' PrEP and TDF2 trials, but not in Fem-PrEP or the Vaginal and Oral Interventions to Control the Epidemic (VOICE) tenofovir arm. Tenofovir gel for topical protection was effective in CAPRISA 004 when used peri-coitally but not in VOICE with daily use. These findings underscore the importance of adherence to achieve adequate drug levels and the potential additive role of PrEP within combination prevention. Pivotal phase III trials are underway of the dapivirine ring, whereas phase I trials of injectable formulations show promise.

SUMMARY

Antiretroviral-based HIV-prevention programmes should be tailored to those most likely to be adherent, providing them with state-of-the-art counselling and support to achieve high adherence during the time period of use. Long-acting products, if found well tolerated and effective, could be ideal for overcoming adherence challenges.

Antiretroviral pre-exposure prophylaxis (PrEP) for preventing HIV in high-risk individuals

BACKGROUND

More than 30 years into the global HIV/AIDS epidemic, infection rates remain alarmingly high, with over 2.7 million people becoming infected every year. There is a need for HIV prevention strategies that are more effective. Oral antiretroviral pre-exposure prophylaxis (PrEP) in high-risk individuals may be a reliable tool in preventing the transmission of HIV.

OBJECTIVES

To evaluate the effects of oral antiretroviral chemoprophylaxis in preventing HIV infection in HIV-uninfected high-risk individuals.

SEARCH METHODS

We revised the search strategy from the previous version of the review and conducted an updated search of MEDLINE, the Cochrane Central Register of Controlled Trials and EMBASE in April 2012. We also searched the WHO International Clinical Trials Registry Platform and ClinicalTrials.gov for ongoing trials.

SELECTION CRITERIA

Randomised controlled trials that evaluated the effects of any antiretroviral agent or combination of antiretroviral agents in preventing HIV infection in high-risk individuals

DATA COLLECTION AND ANALYSIS

Data concerning outcomes, details of the interventions, and other study characteristics were extracted by two independent authors using a standardized data extraction form. Relative risk with a 95% confidence interval (CI) was used as the measure of effect.

MAIN RESULTS

We identified 12 randomised controlled trials that meet the criteria for the review. Six were ongoing trials, four had been completed and two had been terminated early. Six studies with a total of 9849 participants provided data for this review. The trials evaluated the following: daily oral tenofovir disoproxil fumarate (TDF) plus emtricitabine (FTC) versus placebo; TDF versus placebo and daily TDF-FTC versus intermittent TDF-FTC. One of the trials had three study arms: TDF, TDF-FTC and placebo arm. The studies were carried out amongst different risk groups, including HIV-uninfected men who have sex with men, serodiscordant couples and other high risk men and women.Overall results from the four trials that compared TDF-FTC versus placebo showed a reduction in the risk of acquiring HIV infection (RR 0.51; 95% CI 0.30 to 0.86; 8918 participants). Similarly, the overall results of the studies that compared TDF only versus placebo showed a significant reduction in the risk of acquiring HIV infection (RR 0.38; 95% CI 0.23 to 0.63, 4027 participants). There were no significant differences in the risk of adverse events across all the studies that reported on adverse events. Also, adherence and sexual behaviours were similar in both the intervention and control groups.

AUTHORS' CONCLUSIONS

Finding from this review suggests that pre-exposure prophylaxis with TDF alone or TDF-FTC reduces the risk of acquiring HIV in high-risk individuals including people in serodiscordant relationships, men who have sex with men and other high risk men and women.

Acceptability of pre-exposure prophylaxis as an HIV prevention strategy: barriers and facilitators to pre-exposure prophylaxis uptake among at-risk Peruvian populations

This study examined pre-exposure prophylaxis (PrEP) acceptability among female sex workers, male-to-female transgendered persons and men who have sex with men in Lima, Peru. Focus groups explored social issues associated with PrEP acceptability and conjoint analysis assessed preferences among eight hypothetical PrEP scenarios with varying attribute profiles and their relative impact on acceptability. Conjoint analysis revealed that PrEP acceptability ranged from 19.8 to 82.5 out of a possible score of 100 across the eight hypothetical PrEP scenarios. Out-of-pocket cost had the greatest impact on PrEP acceptability (25.2, P < 0.001), followed by efficacy (21.4, P < 0.001) and potential side-effects (14.7, P < 0.001). Focus group data supported these findings, and also revealed that potential sexual risk disinhibition, stigma and discrimination associated with PrEP use, and mistrust of health-care professionals were also concerns. These issues will require careful attention when planning for PrEP roll-out.

Socioecological influences on community involvement in HIV vaccine research

OBJECTIVE

This study investigated socioecological factors influencing HIV vaccine research participation among communities living in geographic areas with high HIV prevalence and high poverty rates.

METHODS

We surveyed a sample of 453 adults ≤18 years from areas of high poverty and high HIV prevalence in metro Atlanta and differentiated the effects of individual-, social/organizational-, and community-level characteristics on participation in HIV vaccine research via multilevel modeling techniques that incorporated questionnaire, program, and census data.

RESULTS

Models that adjusted for both individual-level covariates (such as race, gender, attitudes, and beliefs concerning HIV research), social/organizational- and community-level factors such as local HIV prevalence rates, revealed that the extent of HIV prevention-related programs and services in census tracts contributed to individuals' likelihood of participation in an HIV vaccine study. Additionally, neighborhood-based organizations offering HIV medical and treatment programs, support groups, and services (e.g., food, shelter, and clothing) encourage greater HIV vaccine research participation.

CONCLUSIONS

The findings support the hypothesis that community-level factors facilitate participation in HIV vaccine research independent of both individual- and social/organizational-level factors.

Oral preexposure anti-HIV prophylaxis for high-risk U.S. populations: current considerations in light of new findings

This article reviews the status of current research evaluating oral preexposure prophylaxis (PrEP) for prevention of HIV infection in high-risk populations. In animal model studies, the use of antiretrovirals has been shown to be effective in preventing HIV acquisition. Early-phase PrEP studies have established safety in humans. Currently, more than 20,000 men and women will soon be enrolled in studies of oral or topical chemoprophylaxis, testing a variety of drug delivery methods including tenofovir disoproxil fumarate (TDF) gel applied vaginally or rectally, as well as oral PrEP using TDF by itself or coformulated with emtricitabine (FTC). The largest global PrEP trial in men who have sex with men (MSM), known as iPrEx has demonstrated that oral chemoprophylaxis can decrease HIV incidence in this population. Although TDF/FTC PrEP was generally well tolerated, side effects such as nausea, as well as mild and reversible renal abnormalities were increased among the men who received active medication, suggesting that PrEP users will need ongoing PrEP clinical monitoring. The prophylactic benefits of TDF/FTC were substantially attenuated by nonadherence, indicating that effective PrEP implementation programs will need to focus on this behavioral variable, in addition to safer sex counseling. This article considers biological, policy, and practical implications of large-scale oral PrEP implementation.

Vaginal microbicide gel for delivery of IQP-0528, a pyrimidinedione analog with a dual mechanism of action against HIV-1

Pyrimidinediones, a novel class of compounds, have previously been shown to possess antiviral activity at nanomolar concentrations. One member of this class of compounds, IQP-0528, was selected as the lead molecule for formulation development owing to its stability at physiologically relevant conditions, wide therapeutic window, and antiviral activity in the nanomolar range. Here, we report the development of two vaginal gels--3.0% hydroxyethyl cellulose (HEC) formulation and a 0.65% Carbopol formulation--for the sustained delivery of IQP-0528. Stability studies under accelerated conditions confirmed the chemical stability of IQP-0528 and mechanical stability of the gel formulation for 3 months. In vitro release studies revealed that diffusion-controlled release of IQP-0528 occurred over 6 h, with an initial lag time of approximately 1 h. Based on the drug release profile, the 3.0% HEC gel was selected as the lead formulation for safety and activity evaluations. The in vitro and ex vivo safety evaluations showed no significant loss in cell viability or significant inflammatory response after treatment with a 3.0% HEC gel containing 0.25% IQP-0528. In an in vitro HIV-1 entry inhibition assay, the lead formulation showed an 50% effective concentration of 0.14 μg/ml for gel in culture media, which corresponds to ∼0.001 μM IQP-0528. The antiviral activity was further confirmed by using polarized cervical explants, in which the formulation showed complete protection against HIV infection. In summary, these results are encouraging and warrant further evaluation of IQP-0528 gel formulations in in vivo models, as well as the development of alternative formulations for the delivery of IQP-0528 as a microbicide.

An extended model of reasoned action to understand the influence of individual- and network-level factors on African Americans' participation in HIV vaccine research

In the United States, the number and proportion of HIV/AIDS cases among black/African Americans continue to highlight the need for new biomedical prevention interventions, including an HIV vaccine, microbicide, or new antiretroviral (ARV) prevention strategies such as pre-exposure prophylaxis (PrEP) to complement existing condom usage, harm reduction methods, and behavioral change strategies to stem the HIV epidemic. Although black/African Americans are disproportionately impacted by HIV/AIDS, their participation in HIV clinical research continues to have unique challenges. We theorize that interaction among multilevel factors creates ideal alignment for minority participation in HIV clinical studies. Thus, we initially set out to test an extended model of reasoned action with 362 participants to understand the interplay of sociopsychological and network-level considerations influencing minority participation in HIV prevention research efforts. In this study, we linked the intrapersonal dimensions of attitudes, beliefs, and normative concerns to community-level components, appraisal of involvement with the clinical research organization, an entity which operates within a networked structure of community partner agencies, and identification with coalition advocacy aims. Various participatory outcomes were explored including involvement in future HIV vaccine community functions, participation in community promotion of HIV vaccine research, and community mobilization. Three-stage least squares estimates indicated similar findings across three models. Significant effects demonstrate the importance of positive attitudes toward HIV vaccine research, favorable health research beliefs, perceived social support for participation, HIV/AIDS issue engagement, and perceived relevance of the clinical research site's mission and values. Identification of these nuanced pathway effects provides implications for tailored community program development.

Sex frequency and sex planning among men who have sex with men in Bangkok, Thailand: implications for pre- and post-exposure prophylaxis against HIV infection

Background

Daily HIV antiretroviral pre-exposure prophylaxis (PrEP) is being evaluated in clinical trials among men who have sex with men (MSM). However, daily PrEP may not be congruent with sexual exposure profiles of MSM. Here, we investigate sex frequency and sex planning to identify and inform appropriate PrEP strategies for MSM.

Methods

We evaluated sex frequency and sex planning in a cohort of HIV-negative MSM in Bangkok, Thailand. Chi-squared test was used to compare reports of sex on different weekdays; logistic regression was used to identify predictors of sex frequency and sex planning.

Results

Of 823 MSM (with a mean age of 28.3 years), 86% reported having sex on two days per week or less, and 65% reported their last sex to have been planned. Sex on the weekend (~30%) was more often reported than sex on weekdays (~23%). In multivariate analysis, use of alcohol, erectile dysfunction drugs, group sex, sex with a foreigner, buying and selling sex, and a history of HIV testing were associated with having sex on three days or more per week. Being aged 22 to 29 years, not identifying as homosexual, having receptive anal intercourse, and not engaging in group sex were associated with unplanned sex.

Conclusions

Intermittently dosed PrEP (as opposed to daily) may be a feasible HIV prevention strategy and should be considered for evaluation in clinical trials. Risk factors for sex frequency and sex planning may help to identify those in need for daily PrEP and those who may not be able to take a timely pre-exposure dose.

Development of topical microbicides to prevent the sexual transmission of HIV

Women comprise almost 50% of the population of people living with HIV and the majority of these women contracted the virus through sexual transmission in monogamous relationships in the developing world. In these environments, where women are not empowered to protect themselves through the negotiation of condom use, effective means of preventing HIV transmission are urgently needed. In the absence of an approved and effective vaccine, microbicides have become the strategy of choice to provide women with the ability to prevent HIV transmission from their infected partners. Topical microbicides are agents specifically developed and formulated for use in either the vaginal or rectal environment that prevent infection by sexually transmitted infectious organisms, including pathogenic viruses, bacteria and fungi. Although a microbicidal product will have many of the same properties as other anti-infective agents and would be similarly developed through human clinical trials, microbicide development bears its own challenges related to formulation and delivery and the unique environment in which the product must act, as well as the requirement to develop a product that is acceptable to the user. Herein, perspectives based on preclinical and clinical microbicide development experience, which have led to an evolving microbicide development algorithm, will be discussed. This article forms part of a special issue of Antiviral Research marking the 25th anniversary of anti-retroviral drug discovery and development, Vol 85, issue 1, 2010.

The past, present, and future of HIV prevention: integrating behavioral, biomedical, and structural intervention strategies for the next generation of HIV prevention

In the past 25 years, the field of HIV prevention research has been transformed repeatedly. Today, effective HIV prevention requires a combination of behavioral, biomedical, and structural intervention strategies. Risk of transmitting or acquiring HIV is reduced by consistent male- and female-condom use, reductions in concurrent and/or sequential sexual and needle-sharing partners, male circumcision, and treatment with antiretroviral medications. At least 144 behavioral prevention programs have been found effective in reducing HIV transmission acts; however, scale up of these programs has not occurred outside of the United States. A series of recent failures of HIV-prevention efficacy trials for biomedical innovations such as HIV vaccines, treating herpes simplex 2 and other sexually transmitted infections, and diaphragm and microbicide barriers highlights the need for behavioral strategies to accompany biomedical strategies. This challenges prevention researchers to reconceptualize how cost-effective, useful, realistic, and sustainable prevention programs will be designed, delivered, tested, and diffused. The next generation of HIV prevention science must draw from the successes of existing evidence-based interventions and the expertise of the market sector to integrate preventive innovations and behaviors into everyday routines.

HIV preexposure prophylaxis in the United States: impact on lifetime infection risk, clinical outcomes, and cost-effectiveness

BACKGROUND

The combination of tenofovir and emtricitabine shows promise as HIV preexposure prophylaxis (PrEP). We sought to forecast clinical, epidemiologic, and economic outcomes of PrEP, taking into account uncertainties regarding efficacy, the risks of developing drug resistance and toxicity, behavioral disinhibition, and drug costs.

METHODS

We adapted a computer simulation of HIV acquisition, detection, and care to model PrEP among men who have sex with men and are at high risk of HIV infection (i.e., 1.6% mean annual incidence of HIV infection) in the United States. Base-case assumptions included 50% PrEP efficacy and monthly tenofovir-emtricitabine costs of $753. We used sensitivity analyses to examine the stability of results and to identify critical input parameters.

RESULTS

In a cohort with a mean age of 34 years, PrEP reduced lifetime HIV infection risk from 44% to 25% and increased mean life expectancy from 39.9 to 40.7 years (21.7 to 22.2 discounted quality-adjusted life-years). Discounted mean lifetime treatment costs increased from $81,100 to $232,700 per person, indicating an incremental cost-effectiveness ratio of $298,000 per quality-adjusted life-year gained. Markedly larger reductions in lifetime infection risk (from 44% to 6%) were observed with the assumption of greater (90%) PrEP efficacy. More-favorable incremental cost-effectiveness ratios were obtained by targeting younger populations with a higher incidence of infection and by improvements in the efficacy and cost of PrEP.

CONCLUSIONS

PrEP could substantially reduce the incidence of HIV transmission in populations at high risk of HIV infection in the United States. Although it is unlikely to confer sufficient benefits to justify the current costs of tenofovir-emtricitabine, price reductions and/or increases in efficacy could make PrEP a cost-effective option in younger populations or populations at higher risk of infection. Given recent disappointments in HIV infection prevention and vaccine development, additional study of PrEP-based HIV prevention is warranted.

Antiretroviral pre-exposure prophylaxis (PrEP) for preventing HIV in high-risk individuals

BACKGROUND

Twenty-five years into the global HIV/AIDS epidemic, infection rates remain alarmingly high, with over 4 million people becoming infected every year. There is a need for HIV prevention strategies that are more effective. Oral antiretroviral pre-exposure prophylaxis (PrEP) in high-risk individuals may be a reliable tool in preventing the transmission of HIV.

OBJECTIVES

To evaluate the risk reduction and side effects of antiretroviral chemoprophylaxis in preventing HIV infection in high-risk individuals

SEARCH STRATEGY

We conducted electronic searches of MEDLINE (1980 through June 2008); the Cochrane Central Register of Controlled Trials (March 2008); EMBASE (June 2008); and AIDSearch (June 2008). We also searched the WHO International Clinical Trials Registry Platform in June 2008 for ongoing or prospective trials.

SELECTION CRITERIA

Randomized controlled trials that evaluated the effects of any antiretroviral agent in preventing HIV infection in high-risk individuals

DATA COLLECTION AND ANALYSIS

Data concerning outcomes, details of the interventions, and other study characteristics were extracted by two independent authors using a standardized data extraction form. The information gathered from each included trial were location of the trial, date, publication status, demographics of participants (e.g. age, gender, risk behaviour), exposure modality, type of antiretroviral drug used, duration of drug use, and outcomes. Relative risk with a 95% confidence interval (CI) was used as the measure of effect. Only one trial met our inclusion criteria, so we did not perform a meta-analysis.

MAIN RESULTS

One randomised controlled trial met the criteria for the review, although it was not completed as planned. The trial did not have the statistical power to answer questions about the efficacy of antiretroviral PrEP for HIV prevention in the assessed risk group.

AUTHORS' CONCLUSIONS

Presently there is no reliable evidence to support the use of any antiretroviral agent for HIV chemoprophylaxis.The value of chemoprophylaxis for HIV prevention cannot be assessed on the basis of the included trial. The result was not statistically significant and, moreover, the trial was not completed as planned; therefore, the use of antiretroviral agents for HIV chemoprophylaxis cannot be recommended at present. To assess the value of antiretroviral agents for HIV chemoprophylaxis, we advocate well-conducted trials with the statistical power to answer questions about PrEP efficacy and safety in various populations and risk groups. These trials also should evaluate other important issues of concern, such as drug safety, adherence, drug resistance, and the effect of PrEP on risk behaviour.

Guidelines for reducing the risk of viral transmission during fertility treatment

These guidelines provide strategies, based on scientific principles and clinical experience, for reducing the risk of virus transmission in couples seeking treatment for infertility.

The impact of pre-exposure prophylaxis (PrEP) on HIV epidemics in Africa and India: a simulation study

BACKGROUND

Pre-exposure prophylaxis (PrEP) is a promising new HIV prevention method, especially for women. An urgent demand for implementation of PrEP is expected at the moment efficacy has been demonstrated in clinical trials. We explored the long-term impact of PrEP on HIV transmission in different HIV epidemics.

METHODOLOGY/PRINCIPAL FINDINGS

We used a mathematical model that distinguishes the general population, sex workers and their clients. PrEP scenarios varying in effectiveness, coverage and target group were modeled in the epidemiological settings of Botswana, Nyanza Province in Kenya, and Southern India. We also studied the effect of condom addition or condom substitution during PrEP use. Main outcome was number of HIV infections averted over ten years of PrEP use. PrEP strategies with high effectiveness and high coverage can have a substantial impact in African settings. In Southern India, by contrast, the number of averted HIV infections in different PrEP scenarios would be much lower. The impact of PrEP may be strongly diminished or even reversed by behavioral disinhibition, especially in scenarios with low coverage and low effectiveness. However, additional condom use during low coverage and low effective PrEP doubled the amount of averted HIV infections.

CONCLUSIONS/SIGNIFICANCE

The public health impact of PrEP can be substantial. However, this impact may be diminished, or even reversed, by changes in risk behavior. Implementation of PrEP strategies should therefore come on top of current condom campaigns, not as a substitution.

Guidelines for reducing the risk of viral transmission during fertility treatment

These guidelines provide strategies, based on scientific principles and clinical experience, for reducing the risk of virus transmission in couples seeking treatment for infertility.

Use of tenofovir disoproxil fumarate and emtricitabine combination in HIV-infected patients

With the continuing spread of HIV infection, particularly in developing countries, cost-effective treatment for its management is a high priority. Truvada (Gilead Sciences) is a single combination pill of the nucleotide reverse transcriptase inhibitors tenofovir disoproxil fumarate and emtricitabine, which is used once daily. It is anticipated to be a clinically potent combination that is free of short-term irritating toxicity. The drug has recently been licensed but there are currently little clinical efficacy data regarding its use. The limited published data have indicated that emtricitabine and lamivudine have equivalent potency, and randomised controlled trials have produced evidence of the efficacy of lamivudine combined with tenofovir disoproxil fumarate in a regimen containing either the non-nucleoside reverse transcriptase inhibitor efavirenz or a protease inhibitor lopinavir/ritonavir. In these trials, long-term durability data are available for < or = 96 weeks.