HIV vaccines: current status worldwide and in Africa

Social support and mental health among adults prior to HIV counseling and testing in Durban, South Africa

Poor social support and mental health may be important modifiable risk factors for HIV acquisition, but they have not been evaluated prior to HIV testing in South Africa. We sought to describe self-perceived mental health and social support and to characterize their independent correlates among adults who presented for voluntary HIV testing in Durban. We conducted a large cross-sectional study of adults (≥18 years of age) who presented for HIV counseling and testing between August 2010 and January 2013 in Durban, South Africa. We enrolled adults presenting for HIV testing and used the Medical Outcomes Study's Social Support Scale (0 [poor] to 100 [excellent]) and the Mental Health Inventory (MHI-3) to assess social support and mental health. We conducted independent univariate and multivariable linear regression models to determine the correlates of lower self-reported Social Support Index and lower self-reported MCH scores. Among 4874 adults surveyed prior to HIV testing, 1887 (39%) tested HIV-positive. HIV-infected participants reported less social support (mean score 66 ± 22) and worse mental health (mean score 66 ± 16), compared to HIV-negative participants (74 ± 21; 70 ± 18; p < 0.0001). In a multivariable analysis, significant correlates of less social support included presenting for HIV testing at an urban hospital, not having been tested previously, not working outside the home, and being HIV-infected. In a separate multivariable analysis, significant correlates of poor mental health were similar, but also included HIV testing at an urban hospital and being in an intimate relationship less than six months. In this study, HIV-infected adults reported poorer social support and worse mental health than HIV-negative individuals. These findings suggest that interventions to improve poor social support and mental health should be focused on adults who do not work outside the home and those with no previous HIV testing.

HIV transmissions by stage and sex role in long-term concurrent sexual partnerships

Most mathematical models used to examine the role of different stages of human immunodeficiency virus (HIV) infection unrealistically assume that HIV is transmitted through one-off contacts or that transmission rates are the same between males and females. We sought to examine whether inferences from previous models are robust to the relaxation of those unrealistic assumptions. We developed a model of HIV transmissions through sexual partnerships assuming that (1) sexual partnerships have variable duration, (2) sexual partnerships are concurrent, and (3) the male-to-female transmission rate is higher than the female-to-male transmission rate, with a focus on the third assumption. Assuming a higher rate for male-to-female than female-to-male transmissions decreases the overall transmission of HIV but increases the equilibrium fraction of transmissions during primary HIV infection (PHI) in long-term partnerships, compared to the case where transmission rates are assumed to be symmetric between males an females. Previous modeling studies that assume symmetric transmission rates between males and females may have overestimated the overall spread of HIV, but underestimated the relative contribution of PHI. To make robust inferences on the role of different stages of HIV infection in the sexual spread of HIV, models should take into account that transmission rates may be asymmetric by sex.

Creating an African HIV clinical research and prevention trials network: HIV prevalence, incidence and transmission

HIV epidemiology informs prevention trial design and program planning. Nine clinical research centers (CRC) in sub-Saharan Africa conducted HIV observational epidemiology studies in populations at risk for HIV infection as part of an HIV prevention and vaccine trial network. Annual HIV incidence ranged from below 2% to above 10% and varied by CRC and risk group, with rates above 5% observed in Zambian men in an HIV-discordant relationship, Ugandan men from Lake Victoria fishing communities, men who have sex with men, and several cohorts of women. HIV incidence tended to fall after the first three months in the study and over calendar time. Among suspected transmission pairs, 28% of HIV infections were not from the reported partner. Volunteers with high incidence were successfully identified and enrolled into large scale cohort studies. Over a quarter of new cases in couples acquired infection from persons other than the suspected transmitting partner.

An assessment of fishing communities around Lake Victoria, Uganda, as potential populations for future HIV vaccine efficacy studies: an observational cohort study

Background

An effective HIV vaccine is still elusive. Of the 9 HIV preventive vaccine efficacy trials conducted to-date, only one reported positive results of modest efficacy. More efficacy trials need to be conducted before one or more vaccines are eventually licensed. We assessed the suitability of fishing communities in Uganda for future HIV vaccine efficacy trials.

Methods

A community-based cohort study was conducted among a random sample of 2191 participants aged 18–49 years. Data were collected on socio-demographic characteristics, HIV risky behaviors, and willingness to participate in future HIV vaccine trials (WTP). Venous blood was collected for HIV serological testing. Retention/follow rates and HIV incidence rates per 100 person years at-risk (pyar) were estimated. Adjusted prevalence proportion ratios (PPRs) of retention and odds ratios (ORs) of lack of WTP were estimated using log-binomial and logistic regression models respectively.

Results

Overall retention rate was 76.9% (1685/2191), highest (89%) among participants who had spent 5+ years in the community and lowest (54.1%) among those with <1 year stay. Significant predictors of retention included tribe/ethnicity, baseline HIV negative status, and longer than 1 year stay in the community. Overall WTP was 89.1% (1953/2191). Lack of WTP was significantly higher among women than men [adj.OR = 1.51 (95% CI, 1.14- 2.00)] and among participants who had stayed in fishing communities for 10 or more years relative to those with less than one year [adj.OR = 1.78 (95% CI, 1.11 - 2.88)]. Overall HIV incidence rate per 100 pyar was 3.39 (95% CI; 2.55 - 4.49). Participants aged 25–29 years had highest incidence rates (4.61 - 7.67/100 pyar) and high retention rates between 78.5 and 83.1%. In a combined analysis of retention and incidence rates participants aged 30+ years had retention rates ~80% but low incidence rates (2.45 - 3.57 per 100 pyar) while those aged 25–29 years had the highest incidence rates (4.61 - 7.67/100 pyar) and retention rates 78.5 - 83.1%.

Conclusions

There is high HIV incidence, retention and WTP among fishing communities around L. Victoria, Uganda which make these communities appropriate for future HIV prevention efficacy studies including vaccine trials.

Bayesian spatial semi-parametric modeling of HIV variation in Kenya

Spatial statistics has seen rapid application in many fields, especially epidemiology and public health. Many studies, nonetheless, make limited use of the geographical location information and also usually assume that the covariates, which are related to the response variable, have linear effects. We develop a Bayesian semi-parametric regression model for HIV prevalence data. Model estimation and inference is based on fully Bayesian approach via Markov Chain Monte Carlo (McMC). The model is applied to HIV prevalence data among men in Kenya, derived from the Kenya AIDS indicator survey, with n = 3,662. Past studies have concluded that HIV infection has a nonlinear association with age. In this study a smooth function based on penalized regression splines is used to estimate this nonlinear effect. Other covariates were assumed to have a linear effect. Spatial references to the counties were modeled as both structured and unstructured spatial effects. We observe that circumcision reduces the risk of HIV infection. The results also indicate that men in the urban areas were more likely to be infected by HIV as compared to their rural counterpart. Men with higher education had the lowest risk of HIV infection. A nonlinear relationship between HIV infection and age was established. Risk of HIV infection increases with age up to the age of 40 then declines with increase in age. Men who had STI in the last 12 months were more likely to be infected with HIV. Also men who had ever used a condom were found to have higher likelihood to be infected by HIV. A significant spatial variation of HIV infection in Kenya was also established. The study shows the practicality and flexibility of Bayesian semi-parametric regression model in analyzing epidemiological data.

Improving ethical and participatory practice for marginalized populations in biomedical HIV prevention trials: lessons from Thailand

Background

This paper presents findings from a qualitative investigation of ethical and participatory issues related to the conduct of biomedical HIV prevention trials among marginalized populations in Thailand. This research was deemed important to conduct, as several large-scale biomedical HIV prevention trials among marginalized populations had closed prematurely in other countries, and a better understanding of how to prevent similar trial closures from occurring in the future was desired.

Methods

In-depth key informant interviews were held in Bangkok and Chiang Mai, Thailand. Interviews were audio recorded, transcribed, translated and thematically analyzed. The Good Participatory Practice Guidelines for Biomedical HIV Prevention Trials (GPP) guided this work.

Results

Fourteen interviews were conducted: 10 with policymakers, academic and community-based researchers and trial staff and four with representatives of non-governmental organizations (NGOs). Suggested ways to improve ethical and participatory practice centered on standards of HIV prevention, informed consent, communication and human rights. In particular, the need to overcome language and literacy differences was identified. Key informants felt communication was the basis of ethical understanding and trust within biomedical HIV prevention trial contexts, and thus fundamental to trial participants' ability to exercise free will.

Discussion

Biomedical HIV prevention trials present opportunities for inclusive and productive ethical and participatory practice. Key informants suggested that efforts to improve practice could result in better relationships between research stakeholders and research investigative teams and by extension, better, more ethical participatory trials. This research took place in Thailand and its findings apply primarily to Thailand. However, given the universality of many ethical considerations, the results of this study can inform the improvement of ethical and participatory practice in other parts of the world where biomedical HIV prevention trials occur, and where clinical trials in marginalized populations continue.

Medical relevance of UK-funded non-human primate research published from January 1997 to July 2012

In 2012, the Bateson Review of research using non-human primates (NHPs) recommended the commissioning of a working group to identify and follow-up the results of UK-funded NHP research of potential benefit for human health (Recommendation 4), but the Medical Research Council (MRC) has postponed implementation of the recommendation. Information on results and potential benefits of NHP research therefore remains unavailable. To fill this gap in knowledge, this study identified all published NHP research studies funded by the MRC, Wellcome Trust and Biotechnology and Biological Sciences Research Council (BBSRC) from January 1997 to July 2012 and assessed full texts for medical relevance. In total, 284 papers were identified, of which 51 (18%) involved invasive NHP research, compared to 176 (61%) which used NHP tissue and cell lines, indicating a shift in research emphasis from invasive whole animal to cell-based research. Of these studies, 98 (35%) were medically relevant, of which 22 had potential therapeutic or public health applications. The relatively low proportion of medical studies together with the small number of applied studies raises questions over the level of investment in medical research and the effectiveness of knowledge transfer from basic to applied research. Implementation of the Bateson Review's Recommendation 4 would address these questions.

Animal models in virus research: their utility and limitations

Viral diseases are important threats to public health worldwide. With the number of emerging viral diseases increasing the last decades, there is a growing need for appropriate animal models for virus studies. The relevance of animal models can be limited in terms of mimicking human pathophysiology. In this review, we discuss the utility of animal models for studies of influenza A viruses, HIV and SARS-CoV in light of viral emergence, assessment of infection and transmission risks, and regulatory decision making. We address their relevance and limitations. The susceptibility, immune responses, pathogenesis, and pharmacokinetics may differ between the various animal models. These complexities may thwart translating results from animal experiments to the humans. Within these constraints, animal models are very informative for studying virus immunopathology and transmission modes and for translation of virus research into clinical benefit. Insight in the limitations of the various models may facilitate further improvements of the models.

The rapidly changing paradigm of HIV prevention: time to strengthen social and behavioural approaches

A decade after the world's leaders committed to fight the global HIV epidemic, UNAIDS notes progress in halting the spread of the virus. Access to treatment has in particular increased, with noticeable beneficial effects on HIV-related mortality. Further scaling-up treatment requires substantial human and financial resources and the continued investments that are required may further erode the limited resources for HIV prevention. Treatment can play a role in reducing the transmission of HIV, but treatment alone is not enough and cost-effective behavioural prevention approaches are available that in recent years have received less priority. HIV prevention may in the future benefit from novel biomedical approaches that are in development, including those that capitalize on the use of treatment. To date, evidence of effectiveness of biomedical prevention in real-life conditions is limited and, while they can increase prevention options, many biomedical prevention approaches will continue to rely on the behaviours of individuals and communities. These behaviors are shaped and constrained by the social, cultural, political and economic contexts that affect the vulnerability of individuals and communities. At the start of the 4(th) decade of the epidemic, it is timely to re-focus on strengthening the theory and practice of behavioural prevention of HIV.

HIV prevention research: taking stock and the way forward

Previous papers in this supplement have reviewed the evidence of the effectiveness of alternative HIV prevention methods from randomized controlled trials and other studies. This paper draws together the main conclusions from these reviews. A conceptual framework is presented that maps the proximal and distal determinants of sexual HIV transmission and helps to identify the stages in the causal pathway at which each intervention approach acts. The advances, gaps and challenges emerging from the reviews of individual intervention methods are summarized and cross-cutting themes identified. Approximately 90% of HIV prevention trials have found no effect on HIV incidence and we explore the alternative explanations for the large number of 'flat' trials. We conclude that there is no single explanation for these flat results, which may be due to interventions that are ineffective or inappropriately targeted or implemented, or to factors related to the design or conduct of trials. We examine the lessons from these flat results and provide recommendations on what should be done differently in future trials. HIV prevention remains of critical importance in an era of expanded delivery of antiretroviral therapy. In future HIV prevention research, it is important that resources are used as efficiently as possible to provide rigorous evidence of the effectiveness of a wider array of complementary prevention tools.