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

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.

Enhancers and barriers to uptake of male circumcision services in Northern Uganda: a qualitative study

Uganda adopted voluntary medical male circumcision (VMMC) in 2010, but uptake remains disproportionately low in the Northern region despite implementing several demand creation strategies. This study explored the socio-cultural and structural enhancers and barriers to uptake of VMMC services in Gulu, a district in Northern Uganda where uptake is lowest. In September 2016, we conducted 19 focus group discussions, 9 in-depth interviews, and 11 key informant interviews with 149 total participants. Data were collected and analyzed thematically using both inductive and deductive approaches, then framed in four levels of the social ecological model. Enhancers included adequate knowledge about VMMC services, being young and single, partner involvement, peer influence, perceived increased libido after circumcision, and availability of free and high-quality VMMC services. Barriers included sexual abstinence during wound healing, penile appearance after circumcision, religion, culture, and misconceptions. Optimizing enhancers and addressing barriers could increase VMMC service uptake in northern Uganda.

Theory-Based Analysis of Interest in an HIV Vaccine for Reasons Indicative of Risk Compensation Among African American Women

Licensure of an HIV vaccine could reduce or eliminate HIV among vulnerable populations. However, vaccine effectiveness could be undermined by risk compensation (RC), defined by an increase in risky behavior due to a belief that the vaccine will confer protection. Interest in an HIV vaccine for reasons indicative of RC may serve as an indicator of actual RC in a postlicensure era. This study assessed factors associated with interest in an HIV vaccine for reasons indicative of RC among African American women aged 18 to 55 years, recruited from a hospital-based family planning clinic in Atlanta, Georgia ( N = 321). Data were collected using audio-computer-assisted surveys. Survey items were guided by risk homeostasis theory and social cognitive theory. Multivariable logistic regression was used to assess determinants of interest in an HIV vaccine for reasons indicative of RC. Thirty-eight percent of the sample expressed interest in an HIV vaccine for at least one reason indicative of RC. In the final model, interest in an HIV vaccine for reasons indicative of RC was positively associated with higher impulsivity, perceived benefits of sexual risk behaviors, and perceived benefits of HIV vaccination; it was negatively associated with having at least some college education, positive future orientation, and self-efficacy for sex refusal. Results suggest that demographic, personality, and theory-based psychosocial factors are salient to wanting an HIV vaccine for reasons indicative of RC, and underscore the need for risk-reduction counseling alongside vaccination during the eventual rollout of an HIV vaccine.

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.

Projected economic evaluation of the national implementation of a hypothetical HIV vaccination program among adolescents in South Africa, 2012

BACKGROUND

Adolescents in South Africa are at high risk of acquiring HIV. The HIV vaccination of adolescents could reduce HIV incidence and mortality. The potential impact and cost-effectiveness of a national school-based HIV vaccination program among adolescents was determined.

METHOD

The national HIV disease and cost burden was compared with (intervention) and without HIV vaccination (comparator) given to school-going adolescents using a semi-Markov model. Life table analysis was conducted to determine the impact of the intervention on life expectancy. Model inputs included measures of disease and cost burden and hypothetical assumptions of vaccine characteristics. The base-case HIV vaccine modelled cost at US$ 12 per dose; vaccine efficacy of 50 %; duration of protection of 10 years achieved at a coverage rate of 60 % and required annual boosters. Incremental cost-effectiveness ratios (ICER) were calculated using life years gained (LYG) serving as the outcome measure. Sensitivity analyses were conducted on the vaccine characteristics to assess parameter uncertainty.

RESULTS

The HIV vaccination model yielded an ICER of US$ 5 per LYG (95 % CI ZAR 2.77-11.61) compared with the comparator, which is considerably less than the national willingness-to-pay threshold of cost-effectiveness. This translated to an 11 % increase in per capita costs from US$ 80 to US$ 89. National implementation of this intervention could potentially result in an estimated cumulative gain of 23.6 million years of life (95 % CI 8.48-34.3 million years) among adolescents age 10-19 years that were vaccinated. The 10 year absolute risk reduction projected by vaccine implementation was 0.42 % for HIV incidence and 0.41 % for HIV mortality, with an increase in life expectancy noted across all age groups. The ICER was sensitive to the vaccine efficacy, coverage and vaccine pricing in the sensitivity analysis.

CONCLUSIONS

A national HIV vaccination program would be cost-effective and would avert new HIV infections and decrease the mortality and morbidity associated with HIV disease. Decision makers would have to discern how these findings, derived from local data and reflective of the South African epidemic, can be integrated into the national long term health planning should a HIV vaccine become available.

A comparison of sexual risk behaviours and HIV seroprevalence among circumcised and uncircumcised men before and after implementation of the safe male circumcision programme in Uganda

BACKGROUND

Although male circumcision reduces the heterosexual HIV transmission risk, its effect may be attenuated if circumcised men increase sexual risk behaviours (SRB) due to perceived low risk. In Uganda information about the protective effects of circumcision has been publicly disseminated since 2007. If increased awareness of the protection increases SRB among circumcised men, it is likely that differences in prevalence of SRB among circumcised versus uncircumcised men will change over time. This study aimed at comparing SRBs and HIV sero-status of circumcised and uncircumcised men before and after the launch of the safe male circumcision programme.

METHODS

Data from the 2004 and 2011 Uganda AIDS Indicator Surveys (UAIS) were used. The analyses were based on generalized linear models, obtaining prevalence ratios (PR) as measures of association between circumcision status and multiple sexual partners, transactional sex, sex with non-marital partners, condom use at last non-marital sex, and HIV infection. In addition we conducted multivariate analyses adjusted for sociodemographic characteristics, and the multivariate models for HIV status were also adjusted for SRB.

RESULTS

Twenty six percent of men were circumcised in 2004 and 28% in 2011. Prevalence of SRB was higher among circumcised men in both surveys. In the unadjusted analysis, circumcision was associated with having multiple sexual partners and non-marital partners. Condom use was not associated with circumcision in 2004, but in 2011 circumcised men were less likely to report condom use with the last non-marital partner. The associations between the other sexual risk behaviours and circumcision status were stable across the two surveys." In both surveys, circumcised men were less likely to be HIV positive (Adj PR 0.55; CI: 0.41-0.73 in 2004 and Adj PR 0.64; CI: 0.49-0.83 in 2011).

CONCLUSIONS

There was higher prevalence of SRBs among circumcised men in both surveys, but the only significant change from 2004 to 2011 was a lower prevalence of condom use among the circumcised. Nevertheless, HIV prevalence was lower among circumcised men. Targeted messages for circumcised men and their sexual partners to continue using condoms even after circumcision should be enhanced to avoid risk compensation.

The effect of risk-taking behaviour in epidemic models

We study an epidemic model that incorporates risk-taking behaviour as a response to a perceived low prevalence of infection that follows from the administration of an effective treatment or vaccine. We assume that knowledge about the number of infected, recovered and vaccinated individuals has an effect in the contact rate between susceptible and infectious individuals. We show that, whenever optimism prevails in the risk behaviour response, the fate of an epidemic may change from disease clearance to disease persistence. Moreover, under certain conditions on the parameters, increasing the efficiency of vaccine and/or treatment has the unwanted effect of increasing the epidemic reproductive number, suggesting a wider range of diseases may become endemic due to risk-taking alone. These results indicate that the manner in which treatment/vaccine effectiveness is advertised can have an important influence on how the epidemic unfolds.