Objectives

To assess willingness to participate (WTP) in hypothetical Phase III preventive HIV vaccine trials, and the impact of trial attributes on WTP, among low socioeconomic, ethnically diverse adults from communities at elevated risk for HIV infection.

Method

Participants (n=123; median age=38; 69% male; 37% Latino; 14% African-American) were recruited in Los Angeles in 2003 using multi-site, venue-based sampling. WTP was assessed for eight hypothetical HIV vaccine trials that varied across seven dichotomous attributes, using a 2(7-4) fractional factorial experimental design. Individual-specific impact of vaccine trial attributes on WTP was estimated using within-individual ANOVA and then meta-analyzed across individuals.

Results

Mean WTP for eight hypothetical vaccine trials ranged from 1.74 to 3.81 (1=highly unlikely, 5=highly likely). Lower WTP was associated with vaccine-induced infection risk (impact=0.88, p<0.0001), false HIV-positives (0.53, p<0.0001), no provision of free HIV medications (0.52, p<0.0001), and longer trial duration (0.27; p=0.0002).

Conclusion

HIV vaccine trial attributes may strongly influence WTP. Although existing candidate vaccines cannot cause HIV infection, perceptions of risk may impede WTP. Eliciting trial preferences and concerns prior to trial implementation may enable accommodation of participant preferences and support tailored interventions to address concerns and misconceptions to facilitate enrollment in safe and ethical trials among vulnerable communities.

Compulsory vaccination is a frequently implemented policy option for ensuring comprehensive vaccine coverage. Ongoing controversies around human papillomavirus vaccine dissemination, and suboptimal coverage, suggest the value of assessing acceptability of compulsory vaccinations-particularly among likely target populations-in advance of their public availability to support evidence-informed interventions. With the first HIV vaccine to demonstrate partial efficacy in a large-scale clinical trial, we examined individual characteristics and attitudes associated with support for compulsory HIV vaccination policy among a diverse, representative sample of adults attending probable HIV vaccine dissemination venues in a large urban county. Participants were recruited using three-stage probability sampling from likely venues for future HIV vaccine dissemination. We used Audio-CASI to administer a 60-min structured questionnaire. Items included endorsement of compulsory HIV vaccination policy, sociodemographic characteristics, injecting drug use, vaccine attitudes and perceived HIV risk. Among 1,225 participants (mean age = 36.8 years; 55.6 % males, 37.6 % non-English speaking Hispanic, 78.8 % heterosexual, 25.7 % injection drug users), almost half (48.2 %) endorsed a compulsory HIV vaccination policy. Non-English speaking Hispanics compared to whites, participants with less than high school education, higher positive vaccine attitude scores and higher perceived HIV risk were significantly more likely, and people who inject drugs significantly less likely to endorse compulsory HIV vaccination. Public health interventions to promote positive vaccine attitudes and accurate perceptions of HIV risk among vulnerable populations, and strategies tailored for people who inject drugs, may build support for compulsory HIV vaccination policy and promote broad HIV vaccine coverage.

Background

Geosocial networking applications (GSN apps) used for meeting sexual partners have become increasingly popular with men who have sex with men (MSM) since 2009. The current study aimed to determine if self-identified HIV-negative, MSM clinic attendees who used GSN apps have an increased incidence of sexually transmitted infections (STI) compared to self-identified HIV-negative, MSM attendees who met sexual partners via in-person venues, such as bars or clubs or through MSM-specific hook-up websites.

Methods

Data were collected between August 2011 and January 2013 on all self-identified HIV-negative, MSM clients visiting the L.A. Gay & Lesbian Center for STI screening. A total of 7184 individuals tested for STIs and self-reported behaviours on drug use and social networking methods to meet sexual partners. Multivariate logistic regression models were used to analyse the results.

Results

Individuals who used GSN apps for meeting sexual partners had greater odds of testing positive for gonorrhoea (OR: 1.25; 95% CI 1.06 to 1.48) and for chlamydia (OR: 1.37; 95% CI 1.13 to 1.65) compared to individuals who met partners through in-person methods only. There were no significant differences in syphilis and HIV incidence between those who met partners via in-person venues only, on the internet or through GSN apps.

Conclusions

The present study concludes that sexual health clinic MSM attendees who are meeting on GSN apps are at greater risk for gonorrhoea and chlamydia than MSM attendees who meet in-person or on the internet. Future interventions should explore the use of these novel technologies for testing promotion, prevention and education.

Objective

To assess HIV vaccine acceptability among high-risk adults in Los Angeles.

Study setting

Sexually transmitted disease clinics, needle/syringe exchange programs, Latino community health/HIV prevention programs.

Study design

Cross-sectional survey using conjoint analysis. Participants were randomly selected using three-stage probability sampling.

Data collection

Sixty-minute structured interviews. Participants rated acceptability of eight hypothetical vaccines, each with seven dichotomous attributes, and reported post-vaccination risk behavior intentions.

Principal findings

Participants (n=1164; 55.7 percent male, 82.4 percent ethnic minority, mean age=37.4 years) rated HIV vaccine acceptability from 28.4 to 88.6; mean=54.5 (SD=18.8; 100-point scale). Efficacy had the greatest impact on acceptability, followed by side effects and out-of-pocket cost. Ten percent would decrease condom use after vaccination.

Conclusions

Findings support development of social marketing interventions to increase acceptability of "partial efficacy" vaccines, behavioral interventions to mitigate risk compensation, and targeted cost subsidies.