HIV sexual risk behavior over 36 months of follow-up in the world's first HIV vaccine efficacy trial

Evolving the gay, bisexual and other men who have sex with men time-based deferral to sexual risk screening for all donors: The contribution of Canadian research programmes

BACKGROUND AND OBJECTIVES

In Canada, the time deferral for gay, bisexual and other men who have sex with men (gbMSM) to donate blood has gradually decreased. In September 2022, this deferral was replaced with sexual behaviour-based screening for all donors. We investigate how data from targeted research programmes addressed knowledge gaps to support this change.

MATERIALS AND METHODS

We conducted a scoping review describing the Canadian literature available before the research programmes relating to (1) behavioural indicators of HIV risk and (2) attitudes to blood donation among gbMSM, current donors and the general population. We summarize the targeted research programmes, their outputs and impact to date.

RESULTS

For question 1, five projects met inclusion criteria. For question 2, three articles met inclusion criteria. Knowledge gaps identified were insufficient evidence of HIV incidence in gbMSM who met other donor eligibility criteria and scant data on opinions and views of blood donation and screening criteria for sexual risk behaviours. The research programmes funded 19 projects at 11 different research sites involving over 100 individual researchers/collaborators resulting in 19 peer-reviewed publications to date. Leveraging existing gbMSM cohorts yielded relevant HIV incidence data to inform safety modelling studies. Findings indicated that sexual behaviour-based screening was acceptable to gbMSM and donors, and donor discomfort around specific questions could be mitigated with clear explanations.

CONCLUSION

Targeted research programmes filled critical knowledge gaps and informed a change to gender-neutral, sexual behaviour-based screening for all donors. Findings supported successful implementation of these changes with research-informed staff training.

Assessment of risk compensation following use of the dapivirine vaginal ring in southwestern Uganda

OBJECTIVES

Participation in HIV prevention trials could trigger risk compensation among participants. We evaluated potential risk compensation following use of a vaginal ring microbicide by women in a phase III trial in southwestern Uganda.

METHODS

We used markers of sexual risk behaviour documented on standardised questionnaires, tested for STIs at baseline and quarterly for 2 years. Risk compensation was defined as a significant increase (trend p<0.05) in the proportion of women reporting risky sexual behaviour or a diagnosed STI between baseline and end of follow-up.

RESULTS

Between September 2013 and December 2016, 197 women (active arm: n=132 and placebo: n=65) were enrolled at the Masaka site. There were decreases in all markers of sexual risk behaviour with statistically significant decreases in only the proportion of women reporting ≥2 sexual partners, p=0.026 and those diagnosed with Trichomonas vaginalis p<0.001 and or Neisseria gonorrhoeae p<0.001 CONCLUSIONS: No evidence of risk compensation was observed in this trial.

TRIAL REGISTRATION NUMBER

NCT01539226.

HIV Care Engagement Among Trans Women of Color in San Francisco Bay Area Demonstration Projects: Findings from the Brandy Martell Project and TransAccess

In the San Francisco Bay Area (SFBA), trans women of color are disproportionately affected by HIV and have poor HIV care outcomes. The Brandy Martell Project and TransAccess were two demonstration projects aimed at increasing HIV care engagement and retention among trans women of color in the SFBA. Both projects took place in clinics with a long history of providing trans health care and social services. Both also relied on peer navigation to address systems barriers and promote HIV care linkage and engagement. Our analysis was to identify associations between intervention exposure and primary HIV care visits, ART prescription, and retention in HIV care. Using GEE, we estimated the association between intervention exposure measures (receipt of intervention, intervention dose, intervention provider, and peer dose) and any primary HIV care visit or ART prescription over the 12-month period. Overall, the Brandy Martell Project and TransAccess interventions had significantly positive associations with HIV care outcomes measured. Peer navigation also had a significantly positive association with HIV care outcomes. These interventions demonstrate promise for engaging and retaining trans women of color in HIV care, and call for future investment in this highly underserved community.

Sexual Behaviours and Practices before and after Phase I/II HIV Vaccine Trial: A Qualitative Study among Volunteers in Dar es Salaam Tanzania

There is limited information about sexual behavior among volunteers who participated in phase I/II human immunodeficiency virus (HIV) vaccine trial. This article describes the sexual behavior, practices before, and after participation in phase I/II HIV vaccine trial in Dar es Salaam, Tanzania. We conducted a qualitative descriptive study involving volunteers who participated in the phase I/II vaccine trial between 2007 and 2010. Purposeful sampling was used to recruit potential informants. Twenty-four in-depth interviews were conducted. The audio-recorded interviews were transcribed verbatim and analyzed using a thematic content analysis approach. The findings revealed that before participation in the HIV vaccine trial, informants were engaging in unprotected multiple sexual relationships. After the completion of the HIV vaccine trial, informants reported strengthened marital relationships, increased understanding of safer sexual practices, and HIV testing. However, the informants reported challenges regarding vaccine-induced seropositivity that adversely affected their sexual and marital relationships. Some informants re-engaged in risky sexual practices because they perceived the experimental vaccine was protective. The informants suggested having continued interventions within the community to enhance safer sexual practices. Participation in phase I/II HIV vaccine trials may positively and negatively influence changes in volunteers' sexual behaviors and practices. The trial interventions appear to improve compliance with safer sexual practices. However, the reported vaccine-induced seropositivity and the perception that experimental vaccines are protective need further appropriate interventions.

Sexual behaviour, changes in sexual behaviour and associated factors among women at high risk of HIV participating in feasibility studies for prevention trials in Tanzania

INTRODUCTION

Risk reduction towards safer behaviour is promoted after enrolment in HIV prevention trials. We evaluated sexual behaviour, changes in sexual behaviour and factors associated with risky behaviour after one-year of follow-up among women enrolled in HIV prevention trials in Northern Tanzania.

METHODS

Self-reported information from 1378 HIV-negative women aged 18-44 enrolled in microbicide and vaccine feasibility studies between 2008-2010,was used to assess changes in behaviour during a 12-month follow-up period. Logistic regression with random intercepts was used to estimate odds ratios for trends in each behaviour over time. A behavioural risk score was derived from coefficients of three behavioural variables in a Poisson regression model for HIV incidence and thereafter, dichotomized to risky vs less-risky behaviour. Logistic regression was then used to identify factors associated with risky behaviour at 12 months.

RESULTS

At baseline, 22% reported multiple partners, 28% were involved in transactional sex and only 22% consistently used condoms with non-regular partners. The proportion of women reporting multiple partners, transactional sex and high-risk sex practices reduced at each 3-monthly visit (33%, 43% and 47% reduction in odds per visit respectively, p for linear trend <0.001 for all), however, there was no evidence of a change in the proportion of women consistently using condoms with non-regular partners (p = 0.22). Having riskier behaviours at baseline, being younger than 16 years at sexual debut, having multiple partners, selling sex and excessive alcohol intake at baseline were strongly associated with increased odds of risky sexual behaviour after 12 months (p<0.005 for all).

CONCLUSION

An overall reduction in risky behaviours over time was observed in HIV prevention cohorts. Risk reduction counselling was associated with decreased risk behaviour but was insufficient to change behaviours of all those at highest risk. Biological HIV prevention interventions such as PrEP for individuals at highest risk, should complement risk reduction counselling so as to minimize HIV acquisition risk.

Evaluating the impact of policies recommending PrEP to subpopulations of men and transgender women who have sex with men based on demographic and behavioral risk factors

INTRODUCTION

Developing guidelines to inform the use of antiretroviral pre-exposure prophylaxis (PrEP) for HIV prevention in resource-limited settings must necessarily be informed by considering the resources and infrastructure needed for PrEP delivery. We describe an approach that identifies subpopulations of cisgender men who have sex with men (MSM) and transgender women (TGW) to prioritize for the rollout of PrEP in resource-limited settings.

METHODS

We use data from the iPrEx study, a multi-national phase III study of PrEP for HIV prevention in MSM/TGW, to build statistical models that identify subpopulations at high risk of HIV acquisition without PrEP, and with high expected PrEP benefit. We then evaluate empirically the population impact of policies recommending PrEP to these subpopulations, and contrast these with existing policies.

RESULTS

A policy recommending PrEP to a high risk subpopulation of MSM/TGW reporting condomless receptive anal intercourse over the last 3 months (estimated 3.3% 1-year HIV incidence) yields an estimated 1.95% absolute reduction in 1-year HIV incidence at the population level, and 3.83% reduction over 2 years. Importantly, such a policy requires rolling PrEP out to just 59.7% of MSM/TGW in the iPrEx population. We find that this policy is identical to that which prioritizes MSM/TGW with high expected PrEP benefit. It is estimated to achieve nearly the same reduction in HIV incidence as the PrEP guideline put forth by the US Centers for Disease Control, which relies on the measurement of more behavioral risk factors and which would recommend PrEP to a larger subset of the MSM/TGW population (86% vs. 60%).

CONCLUSIONS

These findings may be used to focus future mathematical modelling studies of PrEP in resource-limited settings on prioritizing PrEP for high-risk subpopulations of MSM/TGW. The statistical approach we took could be employed to develop PrEP policies for other at-risk populations and resource-limited settings.

Per-partner condom effectiveness against HIV for men who have sex with men

OBJECTIVE

Few studies have examined condom effectiveness for HIV prevention among MSM. We estimated condom effectiveness per partner in four cohorts of MSM during 1993-2003 (JumpStart, Vaccine Preparedness Study, VAX004 and Project Explore).

METHODS

We used logistic regression to estimate the increase in odds of new HIV infection per HIV-positive partner for condom-protected receptive anal intercourse (PRAI; partners with whom condoms were always used) and condomless (unprotected) receptive anal intercourse (URAI; partners with whom condoms were sometimes or never used). To estimate condom effectiveness for preventing HIV transmission, we applied the concept of excess odds, the odds ratio minus 1. The condom failure rate was estimated as the excess odds per PRAI partner divided by the excess odds per URAI partner. Condom effectiveness was then 1 minus the failure rate.

RESULTS

The excess odds of HIV infection per HIV-positive partner were 83% for URAI and 7% for PRAI. The resulting failure rate (9%) indicated per-partner condom effectiveness of 91% (95% confidence interval 69-101).

CONCLUSION

The increase in odds of new HIV infection per HIV-positive partner for receptive anal intercourse was reduced by 91% for each partner with whom condoms were always used.

HIV-Infected Young Men Demonstrate Appropriate Risk Perceptions and Beliefs about Safer Sexual Behaviors after Human Papillomavirus Vaccination

The aim of this study was to identify risk perceptions after human papillomavirus (HPV) vaccination among HIV-infected young men who have sex with men. On average, participants appropriately perceived themselves to be at lower than neutral risk for HPV (mean subscale score 4.2/10), at higher than neutral risk for other sexually transmitted infections (7.0/10), and that safer sexual behaviors were still important (8.5/10). Higher perceived risk of HPV was associated with African-American race (p = .03); higher perceived risk of other sexually transmitted infections with White race (p = .01) and higher knowledge about HPV (p = .001); and higher perceived need for safer sexual behaviors with consistent condom use (p = .02). The study provides reassuring data that HIV-infected young men who have sex with men generally have appropriate risk perceptions and believe that safer sexual behaviors after vaccination are still important. These findings mirror the results of studies in HIV-infected young women and HIV-uninfected adolescents.

Preexposure prophylaxis guidelines have low sensitivity for identifying seroconverters in a sample of young Black MSM in Chicago

BACKGROUND

Identification of clients at greatest risk of acquiring HIV is critical for preexposure prophylaxi (PrEP) implementation. Young black MSM (YBMSM) have high incidence of HIV. We examined published guidelines in identifying eligible PrEP candidates, including seroconverters, in a representative cohort of YBMSM.

METHODS

The uConnect cohort included YBMSM aged 16-29 years during PrEP roll-out in Chicago from 2013 and 2016. YBMSM with indications for PrEP were determined using Center for Disease Control and Prevention (CDC) guidelines, the HIV incidence risk index for MSM (HIRI-MSM) scoring tool, and Gilead recommendations with calculation of sensitivities, specificities, and area under the curve (AUC) for HIV seroconversion over 18 months. Incidence rate ratios (IRRs) using Poisson regression were modeled to compare individual and network factors associated with seroconversion.

RESULTS

In the study cohort, 300 HIV uninfected YBMSM contributed 390.4 person-years of follow-up [mean age (SD), 22.3 years (3.07)]. HIV incidence was 8.5 cases per 100 person-years (95% confidence interval, 6.0-11.9). One network factor was associated with seroconversion: having partners more than 10 years older (IRR = 4.4, 95% confidence interval, 1.6-11.8). Overall, 49% of the cohort had an indication for PrEP using CDC guidelines; 72% using HIRI-MSM, and 86% using Gilead recommendations. HIV seroconverters (n = 33) were identified as PrEP eligible prior to seroconversion with sensitivities/AUCs for CDC (52%/0.51), HIRI-MSM (85%/0.57), and Gilead guidelines (94%/0.54).

CONCLUSION

Low sensitivity of CDC guidelines and limited AUC of HIRI-MSM and Gilead screening tools are of concern for PrEP implementation among most at risk populations such as YBMSM. Consideration of demographics, local epidemiology, and network factors may better guide identification of clients who could benefit most from PrEP.

Evaluation of Sexual Risk Behavior Among Study Participants in the TDF2 PrEP Study Among Heterosexual Adults in Botswana

OBJECTIVE

Among participants of a clinical trial to test the efficacy of tenofovir/emtricitabine in protecting heterosexual men and women living in Botswana from HIV infection, the aim was to determine (1) if sexual risk behavior, specifically condomless sex acts and number of sex partners, changed over time, (2) factors associated with condomless sex acts and number of sex partners, and (3) the effect of participant treatment arm perception on risk behavior to address the possibility of risk compensation.

METHODS

A longitudinal modeling of rates of risk behaviors was used to determine if the rate of condomless sex acts (#acts/person) and rate of sex partners (#partners/person) changed over time and which factors were associated with behavior change.

RESULTS

One thousand two hundred participants were analyzed over 1 year. There was a 25% decrease in the rate of sex partners among participants sexually active in the last 30 days. The rate of reported condomless sex acts was greater for males [rate ratio (RR) = 1.34; confidence interval (CI): 1.07 to 1.67] and participants whose sexual debut in years was ≤15 years of age (RR = 1.65; CI: 1.14 to 2.38) and 16-17 (RR = 1.68; CI: 1.22 to 2.31) compared with those ≥20 years. Rate of reported sex partners was greater for males (RR = 3.67; CI: 2.86 to 4.71) and participants whose age at sexual debut in years was ≤15 (RR = 2.92; CI: 2.01 to 4.22) and 16-17 (RR = 2.34; CI: 1.69 to 3.24) compared with those ≥20. There was no effect of participant treatment arm perception on risk behavior.

CONCLUSIONS

Our study of preexposure prophylaxis to prevent HIV infection found no evidence of risk compensation which may have been due to participants' motivations to reduce their risk behaviors and risk-reduction counseling.

Exploring evidence for behavioral risk compensation among participants in an HIV vaccine clinical trial

BACKGROUND

HIV vaccine trial participants may engage in behavioral risk compensation due to a false sense of protection. We conducted an ancillary study of an HIV Vaccine Trials Network (HVTN) vaccine efficacy trial to explore risk compensation among trial participants compared to persons who were willing to participate but ineligible based on previous exposure to the Ad5 virus (Ad5+) across three timepoints.

METHODS

Participants were drawn from the Atlanta, GA site of the HVTN 505 vaccine trial. From 2011-2013, all persons who met prescreening criteria for the clinical trial and presented for Ad5 antibody testing were invited to participate in the ancillary study. Data were collected from vaccine trial participants (n=51) and Ad5+ participants (n=60) via online surveys across three timepoints: baseline, T2 (after trial participants received 2/4 injections) and T3 (after trial participants received 4/4 injections). Data analyses assessed demographic, psychosocial, and behavioral differences at baseline and changes at each timepoint.

RESULTS

At baseline, Ad5+ participants were less likely to have some college education (p=0.024) or health insurance (p=0.008), and were more likely to want to participate in the vaccine trial "to feel safer having unprotected sex" (p=0.005). Among vaccine trial participants, unprotected anal sex with a casual partner (p=0.05), HIV transmission worry (p=0.033), and perceived chance of getting HIV (p=0.027), decreased across timepoints.

CONCLUSIONS

Study findings suggest that persons with previous exposure to Ad5 may be systematically different from their Ad5-negative peers. Unprotected anal sex with a casual partner significantly decreased among HIV vaccine trial participants, as did HIV worry and perceived chance of getting HIV. Findings did not support evidence of risk compensation among HIV vaccine trial participants compared to Ad5+ participants.

Potential Behavioural and Psychological Contributions to Ethical HIV Vaccine Trials in South Africa

The development of an HIV vaccine is one of the best hopes for the future of the HIV pandemic. HIV vaccine trials involve multiple disciplines and professions, including psychologists and other behavioural scientists. One of the most important aspects of HIV vaccine trials, like all clinical trials, is their ethical conduct. This article argues that many of the ethical issues in HIV vaccine trials have strong behavioural (including psychological) components and implications. The article goes on to examine three complex ethical issues, namely informed consent, harm monitoring, and adolescent participation, to illustrate the contribution that psychologists have to make to these ethical issues. First, it is argued that informed consent (IC), which is an essential ethical prerequisite for trials, relies on certain behavioural components as, for example, in determining how understanding can best be assessed. Also, behavioural research can add to the controversial debate about whether IC could be viewed as a culture-bound phenomenon, or whether first-person consent should be done away with in certain cultural contexts. Second, the issue of harms from trial participation is examined. We argue that assessing and minimising social and behavioural harms for participants — an essential demonstration of ongoing respect for participants — can be usefully informed by behavioural science assessment techniques and counselling. Third, the article addresses the role behavioural science can play in the sensitive ethical issue of adolescent participation in HIV vaccine trials. We argue that psychology can inform the complex assessment of whether adolescents are able to make informed and voluntary decisions about their participation in trials. The article concludes that the contribution of psychology to the ethical conduct of HIV vaccine trials may be seen as a novel and unique contribution of psychology to health research.

Sexual Behaviors of US Women at Risk of HIV Acquisition: A Longitudinal Analysis of Findings from HPTN 064

We describe the sexual behaviors of women at elevated risk of HIV acquisition who reside in areas of high HIV prevalence and poverty in the US. Participants in HPTN 064, a prospective HIV incidence study, provided information about individual sexual behaviors and male sexual partners in the past 6 months at baseline, 6- and 12-months. Independent predictors of consistent or increased temporal patterns for three high-risk sexual behaviors were assessed separately: exchange sex, unprotected anal intercourse (UAI) and concurrent partnerships. The baseline prevalence of each behavior was >30 % among the 2,099 participants, 88 % reported partner(s) with >1 HIV risk characteristic and both individual and partner risk characteristics decreased over time. Less than high school education and food insecurity predicted consistent/increased engagement in exchange sex and UAI, and partner's concurrency predicted participant concurrency. Our results demonstrate how interpersonal and social factors may influence sustained high-risk behavior by individuals and suggest that further study of the economic issues related to HIV risk could inform future prevention interventions.

Regression to the mean and changes in risk behavior following study enrollment in a cohort of U.S. women at risk for HIV

PURPOSE

Reductions in risk behaviors are common following enrollment in human immunodeficiency virus (HIV) prevention studies. We develop methods to quantify the proportion of change in risk behaviors that can be attributed to regression to the mean versus study participation and other factors.

METHODS

A novel model that incorporates both regression to the mean and study participation effects is developed for binary measures. The model is used to estimate the proportion of change in the prevalence of "unprotected sex in the past 6 months" that can be attributed to study participation versus regression to the mean in a longitudinal cohort of women at risk for HIV infection who were recruited from ten U.S. communities with high rates of HIV and poverty. HIV risk behaviors were evaluated using audio computer-assisted self-interviews at baseline and every 6 months for up to 12 months.

RESULTS

The prevalence of "unprotected sex in the past 6 months" declined from 96% at baseline to 77% at 12 months. However, this change could be almost completely explained by regression to the mean.

CONCLUSIONS

Analyses that examine changes over time in cohorts selected for high- or low- risk behaviors should account for regression to the mean effects.

Effects of messaging about multiple biomedical and behavioral HIV prevention methods on intentions to use among US MSM: results of an experimental messaging study

Combining multiple biomedical and behavioral HIV prevention approaches is a priority for at-risk populations such as men who have sex with men (MSM), and it is essential to understand how receiving messages about multiple approaches impacts attitudes and intentions for their use. We examined whether receiving combinations of different HIV prevention messages produced differences in perceived benefits and costs of condom use, and in intentions to use condoms and biomedical prevention approaches. MSM (N = 803) were recruited online and were randomly assigned to view informational messages about one, two, or four of the following prevention options: pre-exposure prophylaxis (PrEP), non-occupational post-exposure prophylaxis (nPEP), rectal microbicides, and condoms. The number of HIV prevention messages did not produce differential attitudes and intentions regarding condoms, nor did it produce changes in attitudes towards unprotected sex. Receiving multiple messages was associated with greater intentions to use PrEP and nPEP, but not rectal microbicides.

Development of an HIV vaccine attitudes scale to predict HIV vaccine acceptability among vulnerable populations: L.A. VOICES

BACKGROUND

Decade-long delays in successful implementation of Hepatitis B vaccines and ongoing obstacles in HPV vaccine roll-out suggest the importance of an implementation science approach to prepare for the effective translation of future HIV vaccines from clinical trials into routine practice. The objective of this study was to test HIV vaccine attitude items to develop reliable scales and to examine their association with HIV vaccine acceptability.

METHODS

HIV vaccine attitude items were assessed as part of the L.A. VOICES survey, a large-scale study conducted among underserved residents of Los Angeles, to identify factors that may influence HIV vaccine acceptability. Participants (n=1225) were randomly selected from public STD clinics, needle exchange sites and Latino community clinics using three-stage, venue-based time space sampling.

RESULTS

Exploratory factor analysis across 20 items revealed four distinct factors - mistrust, HIV vaccine social concerns, risk compensation, and altruistic vaccination - with acceptable reliability coefficients for each subscale (Cronbach's α range 0.61-0.84). We found no significant differences in reliability by gender or by vaccine acceptability. Risk compensation (odds ratio (OR)=1.49; 95% CI=[1.18, 1.89]; p=0.001) and altruistic vaccination (OR=1.40; 95% CI=[1.14, 1.71]; p=0.001) were significantly and positively associated with HIV vaccine acceptability.

CONCLUSIONS

We identified four HIV vaccine attitude scales with sound internal reliability parameters. In the aftermath of the first candidate vaccine to demonstrate efficacy against HIV infection, these scales may be helpful in bridging expectable research-to-practice gaps in future HIV vaccine dissemination among populations at risk. As HIV vaccine trials progress in the United States and globally, these measures also may be useful as a tool to assess and facilitate effective responses to community concerns about HIV vaccine trials and to target interventions to support recruitment and mitigate risk compensation.

Will HIV vaccination reshape HIV risk behavior networks? A social network analysis of drug users' anticipated risk compensation

BACKGROUND

An HIV vaccine could substantially impact the epidemic. However, risk compensation (RC), or post-vaccination increase in risk behavior, could present a major challenge. The methodology used in previous studies of risk compensation has been almost exclusively individual-level in focus, and has not explored how increased risk behavior could affect the connectivity of risk networks. This study examined the impact of anticipated HIV vaccine-related RC on the structure of high-risk drug users' sexual and injection risk network.

METHODS

A sample of 433 rural drug users in the US provided data on their risk relationships (i.e., those involving recent unprotected sex and/or injection equipment sharing). Dyad-specific data were collected on likelihood of increasing/initiating risk behavior if they, their partner, or they and their partner received an HIV vaccine. Using these data and social network analysis, a "post-vaccination network" was constructed and compared to the current network on measures relevant to HIV transmission, including network size, cohesiveness (e.g., diameter, component structure, density), and centrality.

RESULTS

Participants reported 488 risk relationships. Few reported an intention to decrease condom use or increase equipment sharing (4% and 1%, respectively). RC intent was reported in 30 existing risk relationships and vaccination was anticipated to elicit the formation of five new relationships. RC resulted in a 5% increase in risk network size (n = 142 to n = 149) and a significant increase in network density. The initiation of risk relationships resulted in the connection of otherwise disconnected network components, with the largest doubling in size from five to ten.

CONCLUSIONS

This study demonstrates a new methodological approach to studying RC and reveals that behavior change following HIV vaccination could potentially impact risk network connectivity. These data will be valuable in parameterizing future network models that can determine if network-level change precipitated by RC would appreciably impact the vaccine's population-level effectiveness.

Accounting for perception, placebo and unmasking effects in estimating treatment effects in randomised clinical trials

There is a rich literature on the role of placebos in experimental design and evaluation of therapeutic agents or interventions. The importance of masking participants, investigators and evaluators to treatment assignment (treatment or placebo) has long been stressed as a key feature of a successful trial design. Nevertheless, there is considerable variability in the technical definition of the placebo effect and the impact of treatment assignments being unmasked. We suggest a formal concept of a 'perception effect' and define unmasking and placebo effects in the context of randomised trials. We employ modern tools from causal inference to derive semi-parametric estimators of such effects. The methods are illustrated on a motivating example from a recent pain trial where the occurrence of treatment-related side effects acts as a proxy for unmasking.

Experiences of social harm and changes in sexual practices among volunteers who had completed a phase I/II HIV vaccine trial employing HIV-1 DNA priming and HIV-1 MVA boosting in Dar es Salaam, Tanzania

Background

Volunteers in phase I/II HIV vaccine trials are assumed to be at low risk of acquiring HIV infection and are expected to have normal lives in the community. However, during participation in the trials, volunteers may encounter social harm and changes in their sexual behaviours. The current study aimed to study persistence of social harm and changes in sexual practices over time among phase I/II HIV vaccine immunogenicity (HIVIS03) trial volunteers in Dar es Salaam, Tanzania.

Methods and Results

A descriptive prospective cohort study was conducted among 33 out of 60 volunteers of HIVIS03 trial in Dar es Salaam, Tanzania, who had received three HIV-1 DNA injections boosted with two HIV-1 MVA doses. A structured interview was administered to collect data. Analysis was carried out using SPSS and McNemars’ chi-square (χ2) was used to test the association within-subjects. Participants reported experiencing negative comments from their colleagues about the trial; but such comments were less severe during the second follow up visits (χ2 = 8.72; P<0.001). Most of the comments were associated with discrimination (χ2 = 26.72; P<0.001), stigma (χ2 = 6.06; P<0.05), and mistrust towards the HIV vaccine trial (χ2 = 4.9; P<0.05). Having a regular sexual partner other than spouse or cohabitant declined over the two follow-up periods (χ2 = 4.45; P<0.05).

Conclusion

Participants in the phase I/II HIV vaccine trial were likely to face negative comments from relatives and colleagues after the end of the trial, but those comments decreased over time. In this study, the inherent sexual practice of having extra sexual partners other than spouse declined over time. Therefore, prolonged counselling and support appears important to minimize risky sexual behaviour among volunteers after participation in HIV Vaccine trials.

Men who have sex with men in Kisumu, Kenya: comfort in accessing health services and willingness to participate in HIV prevention studies

Men who have sex with men (MSM) are a crucial and marginalized at risk population for HIV in Africa but are poorly studied. Like other areas of Africa, homosexuality is illegal in Kenya. We assessed MSM comfort in accessing health services and willingness to participate in HIV prevention research in Kisumu, Kenya-an area of high HIV prevalence. We conducted a two-phase formative study with individual interviews (n = 15) and a structured survey (n = 51). Peer contact or snowball method (n = 43, 84.3%) was the primary recruitment strategy used to locate MSM. Exact logistic regression models were used for survey data analysis. Over 60% (32/51) of survey participants were not very comfortable seeking health services from a public hospital. Almost all MSM (49/51; 96.1%) reported willingness to be contacted to participate in future HIV research studies. Efforts to provide facilities that offer safe and confidential health services and health education for MSM is required. Continued community engagement with the MSM population in Kenya is needed to guide best practices for involving them in HIV prevention research.

No evidence of sexual risk compensation in the iPrEx trial of daily oral HIV preexposure prophylaxis

Objective

Preexposure prophylaxis (PrEP) with emtricitabine/tenofovir disoproxil fumarate (FTC/TDF) reduced HIV acquisition in the iPrEx trial among men who have sex with men and transgender women. Self-reported sexual risk behavior decreased overall, but may be affected by reporting bias. We evaluated potential risk compensation using biomarkers of sexual risk behavior.

Design and methods

Sexual practices were assessed at baseline and quarterly thereafter; perceived treatment assignment and PrEP efficacy beliefs were assessed at 12 weeks. Among participants with ≥1 follow-up behavioral assessment, sexual behavior, syphilis, and HIV infection were compared by perceived treatment assignment, actual treatment assignment, and perceived PrEP efficacy.

Results

Overall, acute HIV infection and syphilis decreased during follow-up. Compared with participants believing they were receiving placebo, participants believing they were receiving FTC/TDF reported more receptive anal intercourse partners prior to initiating drug (12.8 vs. 7.7, P = 0.04). Belief in receiving FTC/TDF was not associated with an increase in receptive anal intercourse with no condom (ncRAI) from baseline through follow-up (risk ratio [RR] 0.9, 95% confidence interval [CI]: 0.6–1.4; P = 0.75), nor with a decrease after stopping study drug (RR 0.8, 95% CI: 0.5–1.3; P = 0.46). In the placebo arm, there were trends toward lower HIV incidence among participants believing they were receiving FTC/TDF (incidence rate ratio [IRR] 0.8, 95% CI: 0.4–1.8; P = 0.26) and also believing it was highly effective (IRR 0.5, 95% CI: 0.1–1.7; P = 0.12).

Conclusions

There was no evidence of sexual risk compensation in iPrEx. Participants believing they were receiving FTC/TDF had more partners prior to initiating drug, suggesting that risk behavior was not a consequence of PrEP use.

Preventive misconception and adolescents' knowledge about HIV vaccine trials

OBJECTIVE

Adolescents have had very limited access to research on biomedical prevention interventions despite high rates of HIV acquisition. One concern is that adolescents are a vulnerable population, and trials carry a possibility of harm, requiring investigators to take additional precautions. Of particular concern is preventive misconception, or the overestimation of personal protection that is afforded by enrolment in a prevention intervention trial.

METHODS

As part of a larger study of preventive misconception in adolescent HIV vaccine trials, we interviewed 33 male and female 16-19-year-olds who have sex with men. Participants underwent a simulated HIV vaccine trial consent process, and then completed a semistructured interview about their understanding and opinions related to enrolment in a HIV vaccine trial. A grounded theory analysis looked for shared concepts, and focused on the content and process of adolescent participants' understanding of HIV vaccination and the components of preventive misconception, including experiment, placebo and randomisation.

RESULTS

Across interviews, adolescents demonstrated active processing of information, in which they questioned the interviewer, verbally worked out their answers based upon information provided, and corrected themselves. We observed a wide variety of understanding of research concepts. While most understood experiment and placebo, fewer understood randomisation. All understood the need for safer sex even if they did not understand the more basic concepts.

CONCLUSIONS

Education about basic concepts related to clinical trials, time to absorb materials and assessment of understanding may be necessary in future biomedical prevention trials.

Sexual risk behavior among HIV-uninfected men who have sex with men participating in a tenofovir preexposure prophylaxis randomized trial in the United States

OBJECTIVE

To evaluate for changes in sexual behaviors associated with daily pill use among men who have sex with men (MSM) participating in a preexposure prophylaxis trial.

DESIGN

Randomized, double-blind, placebo-controlled trial. Participants were randomized 1:1:1:1 to receive tenofovir disoproxil fumarate or placebo at enrollment or after a 9-month delay and followed for 24 months.

METHODS

Four hundred HIV-negative MSM reporting anal sex with a man in the past 12 months and meeting other eligibility criteria enrolled in San Francisco, Atlanta, and Boston. Sexual risk was assessed at baseline and quarterly visits using Audio Computer-Assisted Self-Interview. The association of pill taking with sexual behavior was evaluated using logistic and negative-binomial regressions for repeated measures.

RESULTS

Overall indices of behavioral risk declined or remained stable during follow-up. Mean number of partners and proportion reporting unprotected anal sex declined during follow-up (P < 0.05), and mean unprotected anal sex episodes remained stable. During the initial 9 months, changes in risk practices were similar in the group that began pills immediately vs. those in the delayed arm. These indices of risk did not differ significantly after initiation of pill use in the delayed arm or continuation of study medication in the immediate arm. Use of poppers, amphetamines, and sexual performance-enhancing drugs were independently associated with one or more indices of sexual risk.

CONCLUSIONS

There was no evidence of risk compensation among HIV-uninfected MSM in this clinical trial. Monitoring for risk compensation should continue now that preexposure prophylaxis has been shown to be efficacious in MSM and other populations and will be provided in open-label trials and other contexts.

Issues in women's participation in a phase III community HIV vaccine trial in Thailand

To assess qualities and outcomes of women participating in a large, community-based HIV vaccine trial, the present study was conducted among female participants of the RV 144 prime-boost trial in Thailand from 2003 to 2009. Qualities of participation refer to complete vaccination, retention, and status change. Outcomes of participation refer to incident rate, adverse event, and participation impact event. A total of 6,334 (38.6%) women participated in the trial, of whom about 50% were classified as low risk and 11% as high risk. About 85% of participants completed four vaccinations and 76% were included in the per-protocol analysis of the on-time vaccination schedule. More women (88%) completed 42 months follow-up compared with men (85%). Women aged 21 and above had more adverse events compared to younger age groups. More women (5%) compared with men (3%) reported participation impact events (PIEs). High-risk women had more PIEs and a higher infection rate compared to the low-risk group. Complete vaccination and retention on last follow-up were more common in married women aged above 21, and being a housewife. Female volunteers showed the same qualities and outcomes of participation as males in the HIV vaccine trial. There was no statistically significant difference in vaccine efficacy between men and women, especially among the high-risk and married women. The study highlighted the important behavioral, social, and cultural issues that could be considered for future HIV vaccine trial designs.

The HVTN503/Phambili HIV vaccine trial: a comparison of younger and older participants

By comparing younger to older participants enrolled in a HIV vaccine efficacy trial, we aimed to gain insights into the inclusion of adolescents in future trials. This was a sub-analysis of a multisite HIV vaccine randomized clinical trial in South Africa, conducted January-September 2007. Motivations for trial enrolment, social harms, adverse events and loss to follow-up were compared between younger (18-20 years old) and older participants (21-35 years old). Both younger (n = 238) and older participants (n = 563) were equally likely to report enrolling for altruistic reasons. Younger females were less likely than older participants to join for trial reimbursement (p = 0.005), while younger males were more likely to enrol because the vaccine may provide protection from HIV-acquisition (p < 0.001). There were no significant differences in the number of social harms reported. Compared to males over 20 years old, 18-20-year-old females were less likely to experience adverse events (OR = 0.1, CI 0.01-0.80) and no more likely to be lost to follow-up (OR = 0.7, CI 0.39-1.25), while 18-20-year-old males were no more likely to experience adverse events (OR = 1.3, CI 0.58-2.83) or loss to follow-up (OR = 0.8, CI 0.51-1.41). Our data support the inclusion of younger participants who are at risk for HIV in future HIV vaccine efficacy trials.

Preparing for the unexpected: the pivotal role of social and behavioral sciences in trials of biomedical HIV prevention interventions

A range of efficacies have been reported for biomedical HIV prevention interventions, including antiretroviral treatment, male circumcision, preexposure prophylaxis, microbicides, and preventive vaccines. This range of efficacies probably results from the influence of multiple inputs and processes during trials, including the strength and target of the intervention, host factors, target population characteristics, level of HIV exposure, and intervention dose. Expertise in social and behavioral sciences, in conjunction with basic science, clinical research, epidemiology, biostatistics, and community, is needed to understand the influence of these inputs and processes on intervention efficacy, improve trial design and implementation, and enable interpretation of trial results. In particular, social and behavioral sciences provide the means for investigating and identifying populations suitable for recruitment into and retention in trials and for developing and improving measures of HIV exposure and intervention dose, all within the larger sociocultural context. Integration of social and behavioral sciences early in idea generation and study design is imperative for the successful conduct of biomedical trials and for ensuring optimal data collection approaches necessary for the interpretation of findings, particularly in cases of unexpected results.

"If It's Not Working, Why Would They Be Testing It?": mental models of HIV vaccine trials and preventive misconception among men who have sex with men in India

BACKGROUND

Informed consent based on comprehension of potential risks and benefits is fundamental to the ethical conduct of clinical research. We explored mental models of candidate HIV vaccines and clinical trials that may impact on the feasibility and ethics of biomedical HIV prevention trials among men who have sex with men (MSM) in India.

METHODS

A community-based research project was designed and implemented in partnership with community-based organizations serving MSM in Chennai and Mumbai. We conducted 12 focus groups (n=68) with diverse MSM and 14 key informant interviews with MSM community leaders/service providers using a semi-structured interview guide to explore knowledge and beliefs about HIV vaccines and clinical trials. Focus groups (60-90 minutes) and interviews (45-60 minutes) were conducted in participants' native language (Tamil in Chennai; Marathi or Hindi in Mumbai), audio-taped, transcribed and translated into English. We explored focus group and interview data using thematic analysis and a constant comparative method, with a focus on mental models of HIV vaccines and clinical trials.

RESULTS

A mental model of HIV vaccine-induced seropositivity as "having HIV" resulted in fears of vaccine-induced infection and HIV stigma. Some participants feared inactivated vaccines might "drink blood" and "come alive". Pervasive preventive misconception was based on a mental model of prevention trials as interventions, overestimation of likely efficacy of candidate vaccines and likelihood of being assigned to the experimental group, with expectations of protective benefits and decreased condom use. Widespread misunderstanding and lack of acceptance of placebo and random assignment supported perceptions of clinical trials as "cheating". Key informants expressed concerns that volunteers from vulnerable Indian communities were being used as "experimental rats" to benefit high-income countries.

CONCLUSIONS

Evidence-informed interventions that engage with shared mental models among potential trial volunteers, along with policies and funding mechanisms that ensure local access to products that demonstrate efficacy in trials, may support the safe and ethical implementation of HIV vaccine trials in India.

Risk behavior among women enrolled in a randomized controlled efficacy trial of an adenoviral vector vaccine to prevent HIV acquisition

OBJECTIVES

Report of risk behavior, HIV incidence, and pregnancy rates among women participating in the STEP study, which is a phase IIB trial of MRKAd5 HIV-1 gag/pol/nef vaccine in HIV-negative individuals who were at high risk of HIV-1.

DESIGN

Prospective multicenter, double-blinded, placebo-controlled trial.

METHODS

Women were from North American, and from Caribbean and South America (CSA) sites. Risk behavior was collected at screening and 6-month intervals. Differences in characteristics between groups were tested with chi-square, two-sided Fisher's exact tests, and Wilcoxon rank-sum tests. Generalized estimating equation models were used to assess behavioral change.

RESULTS

Among 1134 enrolled women, the median number of male partners was 18; 73.8% reported unprotected vaginal sex, 15.9% unprotected anal sex and 10.8% evidence of a sexually transmitted infection in the 6 months prior to baseline. With 3344 person-years of follow-up, there were 15 incident HIV infections: incidence rate was 0.45 per 100 person-years [95% confidence interval (CI) 0.25, 0.74]. Crack cocaine use in both regions [relative risk (RR) 2.4 (1.7, 3.3)] and in CSA, unprotected anal sex [RR 6.4 (3.8, 10.7)], and drug use [RR 4.1 (2.1, 8.0)] were baseline risk behaviors associated with HIV acquisition. There was a marked reduction in risk behaviors after study enrollment with some recurrence in unprotected vaginal sex. Of 963 nonsterilized women, 304 (31.6%) became pregnant.

CONCLUSION

Crack cocaine use and unprotected anal sex are important risk criteria to identify high-risk women for HIV-efficacy trials. Pregnancy during the trial was a common occurrence and needs to be considered in trial planning for prevention trials in women.

Anticipated changes in sexual risk behaviour following vaccination with a low-efficacy HIV vaccine: survey results from a South African township

We assessed the potential for anticipated changes in sexual risk-taking behaviour following hypothetical administration of a low-efficacy preventive HIV vaccine. We developed a survey and collected self-reported data from 158 HIV-negative volunteers in a cohort undergoing prescreening for Phase I/II HIV vaccine trials in Soweto. Overall, 22% reported they might use condoms less frequently; 9% reported that they might increase their frequency of sex with casual/anonymous partners; and 55% reported their sexual partners might want to use condoms less frequently knowing they were vaccinated. Multivariate analyses revealed that anticipated decrease in condom use was predicted by poor comprehension and by young age. Individuals may increase their risk-taking behaviour knowing that a vaccine would provide only incomplete protection against HIV transmission. In HIV vaccine trials and future vaccination programmes, education and risk-reduction counselling will be needed for vaccinated individuals and their partners, and mass media education campaigns may be necessary.

Does participation in an HIV vaccine efficacy trial affect risk behaviour in South Africa?

BACKGROUND

Increased sexual risk behaviour in participants enrolled in HIV prevention trials has been a concern. The HVTN 503/Phambili study, a phase 2B study of the Merck Ad-5 multiclade HIV vaccine in South Africa, suspended enrollment and vaccinations following the results of the Step study. Participants were notified of their treatment allocation and continue to be followed. We investigated changes in risk behaviour over time and assessed the impact of study unblinding.

METHODS

801 participants were enrolled. Risk behaviours were assessed with an interviewer-administered questionnaire at 6-month intervals. We assessed change from enrolment to the first 6-month assessment pre-unblinding and between enrolment and at least 6 months post-unblinding on all participants with comparable data. A one-time unblinding risk perception questionnaire was administered post-unblinding.

RESULTS

A decrease in participants reporting unprotected sex was observed in both measured time periods for men and women, with no differences by treatment arm. At 6 months (pre-unblinding), 29.6% of men and 35.8% of women reported changing from unprotected to protected sex (p<0.0001 for each). Men (22%) were more likely than women (14%) to report behaviour change after unblinding (p=0.009). Post-enrolment, 142 (45%) of 313 previously uncircumcised men underwent medical circumcision. 663 participants completed the unblinding questionnaire. More vaccine (24.6%) as compared to placebo recipients (12.0%) agreed that they were more likely to get HIV than most people (p<0.0001), and attributed this to receiving the vaccine.

CONCLUSION

We did not find evidence of risk compensation during this clinical trial. Some risk behaviour reductions including male circumcision were noted irrespective of treatment allocation.

Seroadaptive practices: association with HIV acquisition among HIV-negative men who have sex with men

BACKGROUND

Although efficacy is unknown, many men who have sex with men (MSM) attempt to reduce HIV risk by adapting condom use, partner selection, or sexual position to the partner's HIV serostatus. We assessed the association of seroadaptive practices with HIV acquisition.

METHODOLOGY/PRINCIPAL FINDINGS

We pooled data on North American MSM from four longitudinal HIV-prevention studies. Sexual behaviors reported during each six-month interval were assigned sequentially to one of six mutually exclusive risk categories: (1) no unprotected anal intercourse (UAI), (2) having a single negative partner, (3) being an exclusive top (only insertive anal sex), (4) serosorting (multiple partners, all HIV negative), (5) seropositioning (only insertive anal sex with potentially discordant partners), and (6) UAI with no seroadaptive practices. HIV antibody testing was conducted at the end of each interval. We used Cox models to evaluate the independent association of each category with HIV acquisition, controlling for number of partners, age, race, drug use, and intervention assignment. 12,277 participants contributed to 60,162 six-month intervals with 663 HIV seroconversions. No UAI was reported in 47.4% of intervals, UAI with some seroadaptive practices in 31.8%, and UAI with no seroadaptive practices in 20.4%. All seroadaptive practices were associated with a lower risk, compared to UAI with no seroadaptive practices. However, compared to no UAI, serosorting carried twice the risk (HR = 2.03, 95%CI:1.51-2.73), whereas seropositioning was similar in risk (HR = 0.85, 95%CI:0.50-1.44), and UAI with a single negative partner and as an exclusive top were both associated with a lower risk (HR = 0.56, 95%CI:0.32-0.96 and HR = 0.55, 95%CI:0.36-0.84, respectively).

CONCLUSIONS/SIGNIFICANCE

Seroadaptive practices appear protective when compared with UAI with no seroadaptive practices, but serosorting appears to be twice as risky as no UAI. Condom use and limiting number of partners should be advocated as first-line prevention strategies, but seroadaptive practices may be considered harm-reduction for men at greatest risk.

Sexual risk behaviors, circumcision status, and preexisting immunity to adenovirus type 5 among men who have sex with men participating in a randomized HIV-1 vaccine efficacy trial: step study

BACKGROUND

The Step Study found that men who had sex with men (MSM) who received an adenovirus type 5 (Ad5) vector-based vaccine and were uncircumcised or had prior Ad5 immunity, had a higher HIV incidence than MSM who received placebo. We investigated whether differences in HIV exposure, measured by reported sexual risk behaviors, may explain the increased risk.

METHODS

Among 1764 MSM in the trial, 726 were uncircumcised, 994 had prior Ad5 immunity, and 563 were both uncircumcised and had prior Ad5 immunity. Analyses compared sexual risk behaviors and perceived treatment assignment among vaccine and placebo recipients, determined risk factors for HIV acquisition, and examined the role of insertive anal intercourse in HIV risk among uncircumcised men.

RESULTS

Few sexual risk behaviors were significantly higher in vaccine versus placebo recipients at baseline or during follow-up. Among uncircumcised men, vaccine recipients at baseline were more likely to report unprotected insertive anal intercourse with HIV-negative partners (24.9% vs. 18.1%; P = 0.03). Among uncircumcised men who had prior Ad5 immunity, vaccine recipients were more likely to report unprotected insertive anal intercourse with partners of unknown HIV status (46.0% vs. 37.8%; P = 0.05). Vaccine recipients remained at higher risk of HIV infection compared with placebo recipients (hazard ratio = 2.8; 95% confidence interval, 1.2-6.8) controlling for potential confounders.

CONCLUSIONS

These analyses do not support a behavioral explanation for the increased HIV infection rates observed among uncircumcised men in the Step Study. Identifying biologic mechanisms to explain the increased risk is a priority .

Development of a clinical screening index predictive of incident HIV infection among men who have sex with men in the United States

BACKGROUND

To implement biomedical and other intensive HIV prevention interventions cost-effectively, busy care providers need validated, rapid, risk screening tools for identifying persons at highest risk of incident infection.

METHODS

To develop and validate an index, we included behavioral and HIV test data from initially HIV-uninfected men who have sex with men who reported no injection drug use during semiannual interviews in the VaxGen VAX004 study and Project Explore HIV prevention trials. Using generalized estimating equations and logistic regression analyses, we identified significant predictors of incident HIV infection, then weighted and summed their regression coefficients to create a risk index score.

RESULTS

The final logistic regression model included age, and the following behaviors reported during the past 6 months: total number of male sex partners, total number of HIV-positive male sex partners, number of times the participant had unprotected receptive anal sex with a male partner of any HIV status, number of times the participant had insertive anal sex with an HIV-positive male partner, whether the participant reported using poppers, and whether they reported using amphetamines. The area under the receiver operating characteristic curve was 0.74, possible scores on index range from 0 to 47 and a score ≥10 had as sensitivity of 84% and a specificity of 45%, levels appropriate for a screening tool.

CONCLUSIONS

We developed an easily administered and scored 7-item screening index with a cutoff that is predictive of HIV seroconversion in 2 large prospective cohorts of US men who have sex with men. The index can be used to prioritize patients for intensive HIV prevention efforts (eg, preexposure prophylaxis).

Condom migration resulting from circumcision, microbicides and vaccines: brief review and methodological considerations

OBJECTIVE

To provide an updated review of condom migration as a means of highlighting methodological issues for future studies of this behavioural issue.

METHODS

Electronic searches of PubMed, MEDLINE and Cumulative Index to Nursing and Allied Health Literature (CINAHL) databases were carried out in October 2010 and updated in January 2011 for English-language articles published from 1994 onward.

RESULTS

Evidence addressing condom migration from microbicides and vaccines is vastly underdeveloped, simply because these products are still experimental. In contrast, the more advanced evidence regarding male circumcision is hopeful because it suggests that migration may not be an overwhelming issue. Nonetheless, the entire body of empirical evidence on this question could be substantially expanded and improved.

CONCLUSION

Until stronger evidence suggests that condom migration is unlikely, it is important to be mindful of the potential for condom migration to occur in response to biomedical interventions (circumcision, microbicides and vaccines).

Risk perceptions after human papillomavirus vaccination in HIV-infected adolescents and young adult women

PURPOSE

To examine risk perceptions (perceived risk of human papillomavirus [HPV], perceived risk of other sexually transmitted infections [STIs], and need for safer sexual behaviors) and to determine factors associated with these risk perceptions after HPV vaccination.

METHODS

Data were collected at the baseline visit of an HPV-6, -11, -16, -18 vaccine clinical trial in 16-23-year-old HIV-infected young women (N = 99). Immediately after receiving the first vaccine dose, participants completed a confidential questionnaire that included three 5-item scales measuring perceived risk of HPV, perceived risk of other STIs, and need for safer sexual behaviors. Linear and logistic regression models were used to examine associations between baseline characteristics (demographic characteristics; cluster of differentiation antigen 4 (CD4(+)) count; HIV viral load; knowledge about HPV and HPV vaccines; sexual behaviors; and STI diagnosis) and each measure of risk perceptions.

RESULTS

Most participants perceived themselves to be at lower risk for HPV (mean scale score = 19.5/50), most perceived that they were not at lower risk for other STIs (mean = 31.2/50), and the vast majority reported that there was still a need for safer sexual behaviors after vaccination (mean = 43.1/50). Multivariate analyses indicated that knowledge about HPV and HPV vaccines was associated with perceived need for safer sexual behaviors (OR = 1.05, 95% CI = 1.0-1.1).

CONCLUSIONS

Although almost all young women in this study believed that safer sexual behaviors were still important after HPV vaccination, a subset believed they were at less risk for STIs other than HPV. Educational interventions are needed to prevent misperceptions and promote healthy behaviors after vaccination.

High and persistent HIV seroincidence in men who have sex with men across 47 U.S. cities

OBJECTIVE

To provide HIV seroincidence data among men who have sex with men (MSM) in the United States and to identify predictive factors for seroconversion.

METHODS

From 1998-2002, 4684 high-risk MSM, age 18-60 years, participated in a randomized, placebo-controlled HIV vaccine efficacy trial at 56 U.S. clinical trial sites. Demographics, behavioral data, and HIV status were assessed at baseline and 6 month intervals. Since no overall vaccine efficacy was detected, data were combined from both trial arms to calculate HIV incidence based on person-years (py) of follow-up. Predictors of seroconversion, adjusted hazards ratio (aHR), were evaluated using a Cox proportional hazard model with time-varying covariates.

RESULTS

Overall, HIV incidence was 2.7/100 py and was relatively uniform across study sites and study years. HIV incidence was highest among young men and men reporting unprotected sex, recreational drug use, and a history of a sexually transmitted infection. Independent predictors of HIV seroconversion included: age 18-30 years (aHR = 2.4; 95% CI 1.4,4.0), having >10 partners (aHR = 2.4; 95% CI 1.7,3.3), having a known HIV-positive male sex partner (aHR = 1.6; 95% CI 1.2, 2.0), unprotected anal intercourse with HIV positive/unknown male partners (aHR = 1.7; 95% CI 1.3, 2.3), and amphetamine (aHR = 1.6; 95% CI 1.1, 2.1) and popper (aHR = 1.7; 95% CI 1.3, 2.2) use.

CONCLUSIONS

HIV seroincidence was high among MSM despite repeated HIV counseling and reported declines in sexual risk behaviors. Continuing development of new HIV prevention strategies and intensification of existing efforts will be necessary to reduce the rate of new HIV infections, especially among young men.

The cost-effectiveness of pre-exposure prophylaxis for HIV infection in South African women

BACKGROUND

Recent trials report the short-term efficacy of tenofovir-based pre-exposure prophylaxis (PrEP) for prevention of human immunodeficiency virus (HIV) infection. PrEP's long-term impact on patient outcomes, population-level transmission, and cost-effectiveness remains unknown.

METHODS

We linked data from recent trials to a computer model of HIV acquisition, screening, and care to project lifetime HIV risk, life expectancy (LE), costs, and cost-effectiveness, using 2 PrEP-related strategies among heterosexual South African women: (1) women receiving no PrEP and (2) women not receiving PrEP (a tenofovir-based vaginal microbicide). We used a South African clinical cohort and published data to estimate population demographic characteristics, age-adjusted incidence of HIV infection, and HIV natural history and treatment parameters. Baseline PrEP efficacy (percentage reduction in HIV transmission) was 39% at a monthly cost of $5 per woman. Alternative parameter values were examined in sensitivity analyses.

RESULTS

Among South African women, PrEP reduced mean lifetime HIV risk from 40% to 27% and increased population discounted (undiscounted) LE from 22.51 (41.66) to 23.48 (44.48) years. Lifetime costs of care increased from $7280 to $9890 per woman, resulting in an incremental cost-effectiveness ratio of $2700/year of life saved, and may, under optimistic assumptions, achieve cost savings. Under baseline HIV infection incidence assumptions, PrEP was not cost saving, even assuming an efficacy >60% and a cost <$1. At an HIV infection incidence of 9.1%/year, PrEP achieved cost savings at efficacies ≥50%.

CONCLUSIONS

PrEP in South African women is very cost-effective by South African standards, conferring excellent value under virtually all plausible data scenarios. Although optimistic assumptions would be required to achieve cost savings, these represent important benchmarks for future PrEP study design.

Adolescent perceptions of risk and need for safer sexual behaviors after first human papillomavirus vaccination

OBJECTIVES

To (1) examine perceptions of risk of human papillomavirus (HPV) and other sexually transmitted infections (STIs), (2) examine perceived need for safer sexual behaviors, and (3) determine factors associated with less perceived need for safer sexual behaviors, all in the context of receiving the first HPV vaccination.

DESIGN

Cross-sectional baseline analysis from an ongoing longitudinal cohort study.

SETTING

An urban hospital-based adolescent primary care clinic.

PARTICIPANTS

Girls 13 to 21 years (for this article girls are defined as being aged 13 to 21 years) (n = 339) receiving their first HPV vaccination and their mothers (n = 235).

MAIN OUTCOME MEASURES

(1) Girls' perceived risk of HPV after HPV vaccination, (2) girls' perceived risk of other STIs after vaccination, (3) girls' perceived need for continued safer sexual behaviors after vaccination, and (4) factors associated with girls' perception of less need for safer sexual behaviors.

RESULTS

Mean age of girls was 16.8 years. Most participants (76.4%) were black, and 57.5% were sexually experienced. Girls perceived themselves to be at less risk for HPV than for other STIs after HPV vaccination (P < .001). Although most girls reported continued need for safer sexual behaviors, factors independently associated with perception of less need for safer sexual behaviors included adolescent factors (lower HPV and HPV vaccine knowledge and less concern about HPV) and maternal factors (lower HPV and HPV vaccine knowledge, physician as a source of HPV vaccine information, and lack of maternal communication about the HPV vaccine).

CONCLUSIONS

Few adolescents perceived less need for safer sexual behaviors after the first HPV vaccination. Education about HPV vaccines and encouraging communication between girls and their mothers may prevent misperceptions among these adolescents.

Awareness of, usage of and willingness to use HIV pre-exposure prophylaxis among men in downtown Toronto, Canada

Pre-exposure prophylaxis (PrEP) is a promising strategy whereby HIV-uninfected people could take antiretroviral (ARV) medications to reduce their risk of HIV acquisition. Reports suggest that unsupervised PrEP use has been occurring in gay communities of USA cities before human safety and efficacy data became available. We administered a 20-item questionnaire to men undergoing HIV testing at Hassle Free Clinic, a sexual health clinic in the gay village of Toronto. Questionnaire items enquired about demographics, sexual partners, substance use and awareness of, usage of and willingness to use PrEP. Logistic regression was used to identify characteristics associated with PrEP-related outcomes. Of 256 participants, 11.7% were aware of PrEP, with more men who have sex with men (MSM) aware (14.1%) than non-MSM (4.9%). No participants reported PrEP usage. Willingness to consider PrEP use was high and associated with high-risk activities, suggesting opportunities for PrEP use in the future.

A qualitative evaluation of volunteers' experiences in a phase I/II HIV vaccine trial in Tanzania

Background

Evaluating experiences of volunteers in an HIV vaccine trial will be useful for the conduct of future trials. The purpose of this study among volunteers who participated in a phase I/II HIV vaccine trial in Dar es Salaam, Tanzania was to assess what characterized their experiences during the trial.

Methods

We conducted four focus group discussions with 35 out of the 60 individuals (women and men) after the five scheduled vaccinations. An interpretive description approach was applied to data analysis.

Results

As a result of the trial interventions, both men and women gained confidence in their own abilities to have safer, less risky sexual behaviour. The participants experienced the trial as a way of accessing free [insured] medical services. Most of the men said they had gone from self-medication to professional medical consultation. Despite these benefits, the participants faced various challenges during the trial. Such challenges included mistrust of the trial shown by health care providers who were not connected to the trial and discouragement from friends, colleagues and family members who questioned the safety of the trial. However, they managed to cope with these doubts by using both personal and trial related interventions.

Conclusion

We found that during the phase I/II HIV vaccine trial, participants had both the opportunities and the ability to cope with the doubts from the surrounding community. Follow up visits enhanced the opportunities and individuals' abilities to cope with the doubts during the trial. Understanding this discourse may be useful for the trial implementers when designing future trials.

Trials Registration

ISRCTN: ISRCTN90053831

Pan African Clinical Trials Registry (PACTR): ATMR2009040001075080

Sexual health, HIV risk, and retention in an adolescent HIV-prevention trial preparatory cohort

PURPOSE

Although adolescents are at high risk for human immunodeficiency virus (HIV) infection, they have not been, included in HIV vaccine trials.

METHODS

In preparation for enrollment in HIV vaccine trials, 100 HIV-negative adolescents aged 14-17 years from Cape Town were recruited into a cohort. HIV, syphilis, pregnancy testing, and sexual risk questionnaires were conducted at varying intervals for a year.

RESULTS

The mean age of the participants was 15 years, and 70% of them were female. Recruitment was completed within 3 months. Retention was found to be 82% at 1-year follow-up. The main reasons for dropout were as follows: relocation to other communities, phlebotomy, and visit frequency. In a Cox proportional hazards model, only female gender was significantly associated with retention. No change in reported sexual risk occurred, but the proportion of individuals who were aware of their partner's HIV status was significantly higher (17% at baseline, 83% at 1-year follow-up; p < .001). Five pregnancies were reported during follow-up.

CONCLUSIONS

To our knowledge, this is the first prospective adolescent HIV-prevention cohort in Southern Africa. Despite reports of risky sexual behaviors and high pregnancy rates, HIV seroconversions did not occur in the retained cohort. HIV-prevention trials with high-risk adolescents will require rigorous efforts to prevent future pregnancies, and may require risk eligibility criteria. Retention may improve with transport provision, visits with incentives, and efforts to retain males.

Assessment of changes in condom use among female sex workers in a prospective cohort study introducing diaphragm use for disease prevention

Changes in the rates of condom use and number of sexual partners were evaluated among 140 female sex workers in Kibera, Kenya, participating in a 6-month study of diaphragm safety and acceptability for prevention of sexually transmitted infections conducted in 2004-2005. Analyses were stratified by partner type. Multivariable Tobit regression modeling was used to assess the association between study visit and proportion of acts protected. Participants completed 140 baseline visits and 390 bimonthly follow-up visits. The mean percentage of coital acts reported as protected by a condom increased from 56% at baseline to 68% at the 6-month visit (P < 0.01). Similar increases were observed for condom use by all partner types. Additionally, the mean number of sexual partners decreased over the study. Furthermore, consistent (i.e., 100%) diaphragm use during follow-up was associated with a higher proportion of coital acts protected by a condom in analyses adjusted for study visit and coital frequency. These findings suggest that, despite concerns that introduction of the diaphragm would result in more risky sexual behaviors, reported condom use increased and number of partners decreased.

Periconception pre-exposure prophylaxis to prevent HIV transmission: benefits, risks, and challenges to implementation

HIV-serodiscordant couples face complicated choices between fulfilling reproductive desire and risking HIV transmission to their partners and children. Sexual HIV transmission can be dramatically reduced through artificial insemination and sperm washing; however, most couples cannot access these resources. We propose that periconception pre-exposure prophylaxis (PrEP) could offer an important, complementary therapy to harm reduction counseling programs that aim to decrease HIV transmission for couples who choose to conceive. In this paper, we describe the potential benefits of periconception PrEP and define critical points of clarification prior to implementation of PrEP as part of a reproductive health program. We consider sexual transmission risk, current risk reduction options, PrEP efficacy, cost, adherence, resistance, fetal toxicity, and impact of PrEP counseling on entry into health services. We address PrEP in the context of other periconception HIV-prevention strategies, including antiretroviral treatment of the HIV-infected partner. We conclude that, should PrEP prove safe and efficacious in ongoing trials, periconception PrEP may offer a useful approach to minimize risk of HIV transmission for individuals of reproductive age in HIV-endemic countries.

Behavioral considerations for engaging youth in HIV clinical research

From both scientific and ethical perspectives, it is important that youth be enrolled in biomedical HIV prevention clinical trials. At the same time, adolescents, as minors, are considered a vulnerable population requiring particular attention to the reduction of potential harm associated with participation in such trials. In this article, we review the evidence supporting enrollment of youth in HIV clinical trials, including data on HIV infection rates, sexual behavior, and cognitive, psychosocial, and neurophysiological development. Next, we address the potential risks associated with clinical trial participation, with a focus on the concept of preventive misconception, the tendencies to (1) overestimate the probability of assignment to the experimental condition, as opposed to the placebo, and (2) assume that the experimental intervention is efficacious. Finally, we discuss targeted interventions to reduce preventive misconception and the importance of developing and testing adolescent-friendly risk-reduction interventions that are tailored to the structure and time frame of a biomedical HIV prevention clinical trial. The very issues that make inclusion of youth in HIV prevention clinical trials necessary also demand that particularly intensive efforts be made to protect participating minors from the harm that could accrue from a clinical trial.

Youth-specific considerations in the development of preexposure prophylaxis, microbicide, and vaccine research trials

Preventing HIV infection in adolescents and young adults will require a multimodal targeted approach, including individual-directed behavioral risk reduction, community-level structural change, and biomedical interventions to prevent sexual transmission. Trials testing biomedical interventions to prevent HIV transmission will require special attention in this population due to the unique psychosocial and physiologic characteristics that differentiate them from older populations. For example, microbicide research will need to consider acceptability, dosing requirements, and coinfection rates that are unique to this population. Preexposure prophylaxis studies also will need to consider potential unique psychosocial issues such as sexual disinhibition and acceptability as well as unique pharmacokinetic parameters of antiretroviral agents. Vaccine trials also face unique issues with this population, including attitudes toward vaccines, risks related to false-positive HIV tests related to vaccine, and different immune responses based on more robust immunity. In this article, we will discuss issues around implementing each of these biomedical prevention modalities in trials among adolescents and young adults to help to guide future successful research targeting this population.