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

Is badger culling associated with risk compensation behaviour among cattle farmers?

BACKGROUND

Risk compensation theory suggests that behaviours are modified in response to interventions that remove risks by substituting them with other risky behaviours to maintain a 'risk equilibrium'. Alternatively, risk reduction interventions may result in spill-over behaviours that seek to minimise risks further. This paper assessed evidence for these behavioural risk responses among farmers in response to badger culling that seeks to remove the risk of bovine tuberculosis in cattle.

METHODS

Data from the UK's randomised badger culling trial were re-analysed, comparing farmers' cattle movement practices in proactive and reactive culling areas and control areas. Analysis compared cattle movements during and after the trial using zero-inflated negative binomial regression.

RESULTS

The analysis found no strong evidence of risk compensation behaviours among farmers who experienced proactive culling. However, strong evidence for a reduction in cattle movements in reactive culling areas was found. The results indicate high levels of inertia within farming systems in relation to cattle purchasing.

LIMITATIONS

Data do not account for the risk of cattle purchases and reflect previous policy regimens. Evidence from recent badger culling interventions should be analysed.

CONCLUSION

Proactive badger culling was not associated with risk compensation behaviours, while reactive badger culling was associated with decreased risk taking among farmers.

Sociometric network analysis in illicit drugs research: A scoping review

BACKGROUND

Sociometric or whole network analysis, a method used to analyze relational patterns among social actors, emphasizes the role of social structure in shaping behaviour. Such method has been applied to many aspects of illicit drug research, including in the areas of public health, epidemiology, and criminology. Previous reviews about social networks and drugs have lacked a focus on the use of sociometric network analysis for illicit drugs research across disciplines. The current scoping review aimed to provide an overview of the sociometric network analysis methods used in illicit drugs research and to assess how such methods could be used for future research.

METHODS

A systematic search of six databases (Web of Science, ProQuest Sociology Collection, Political Science Complete, PubMed, Criminal Justice Abstracts, and PsycINFO) returned 72 relevant studies that met the inclusion criteria. To be included, studies had to mention illicit drugs and use whole social network analysis as one of their methods. Studies were summarized quantitatively and qualitatively using a data-charting form and a description of the studies' main topics.

RESULTS

Sociometric network analysis in illicit drugs research has grown in popularity in the last decade, using mostly descriptive network metrics, such as degree centrality (72.2%) and density (44.4%). Studies were found to belong to three study domains. The first, drug crimes investigated network resilience and collaboration patterns in drug trafficking networks. The second domain, public health, focused on the social networks and social support of people who use drugs. Finally, the third domain focused on the collaboration networks of policy, law enforcement, and service providers.

CONCLUSION

Future illicit drugs research using whole network SNA should include more diverse data sources and samples, incorporate mixed and qualitative methods, and apply social network analysis to study drug policy.

Association between health behaviours and the COVID-19 vaccination: risk compensation among healthcare workers in Taizhou, China

This study is conducted to explore the association between health behaviors and the COVID-19 vaccination based on the risk compensation concept among health-care workers in Taizhou, China. We conducted a self-administered online survey to estimate the health behaviors among the staff in a tertiary hospital in Taizhou, China, from May 18 to 21 May 2021. A total of 592 out of 660 subjects (89.7%) responded to the questionnaire after receiving an e-poster on WeChat. Subjects who had been inoculated with the COVID-19 vaccine were asked to mention the differences in their health behaviors before and after the vaccination. The results showed that there were no statistical differences in health behaviors between vaccinated and unvaccinated groups, except in terms of the type of gloves they used (62.8% in the vaccinated group and 49.2% in the unvaccinated group, p = .048). Subjects who received earlier COVID-19 vaccinations exhibited better health behaviors (22.40% increased for duration of wearing masks (P = .007), 25.40% increased for times of washing hands (P = .01), and 20.90% increased for times of wearing gloves (P = .01)). Subjects also revealed better health behaviors (washing hands, wearing gloves, and wearing masks) after vaccination compared to that before. In conclusion, concept of risk compensation was not applied in our findings. The health behaviors did not reduce after the COVID-19 vaccination, which even may improve health behaviors among health-care workers in the hospital setting.

Risk compensation after HIV-1 vaccination may accelerate viral adaptation and reduce cost-effectiveness: a modeling study

Pathogen populations can evolve in response to selective pressure from vaccine-induced immune responses. For HIV, models predict that viral adaptation, either via strain replacement or selection on de novo mutation, may rapidly reduce the effectiveness of an HIV vaccine. We hypothesized that behavioral risk compensation after vaccination may accelerate the transmission of vaccine resistant strains, increasing the rate of viral adaptation and leading to a more rapid decline in vaccine effectiveness. To test our hypothesis, we modeled: (a) the impact of risk compensation on rates of HIV adaptation via strain replacement in response to a partially effective vaccine; and (b) the combined impact of risk compensation and viral adaptation on vaccine-mediated epidemic control. We used an agent-based epidemic model that was calibrated to HIV-1 trends in South Africa, and includes demographics, sexual network structure and behavior, and within-host disease dynamics. Our model predicts that risk compensation can increase the rate of HIV viral adaptation in response to a vaccine. In combination, risk compensation and viral adaptation can, under certain scenarios, reverse initial declines in prevalence due to vaccination, and result in HIV prevalence at 15 years equal to or greater than prevalence without a vaccine.

An assessment of risk compensation and spillover behavioural adaptions associated with the use of vaccines in animal disease management

This paper analyses farmers' behavioural responses to Government attempts to reduce the risk of disease transmission from badgers to cattle through badger vaccination. Evidence for two opposing behavioural adaptions is examined in response to the vaccination of badgers to reduce the risk of transmission to farmed cattle. Risk compensation theory suggests that interventions that reduce risk, such as vaccination, are counterbalanced by negative behavioural adaptions. By contrast, the spillover effect suggests that interventions can prompt further positive behaviours. The paper uses data from a longitudinal mixed methods study of farmers' attitudes to badger vaccination to prevent the spread of bovine tuberculosis, their reports of biosecurity practices, and cattle movement data in 5 areas of England, one of which experienced badger vaccination. Analysis finds limited evidence of spillover behaviours following vaccination. Lack of spillover is attributed to farmers' beliefs in the effectiveness of biosecurity and the lack of similarity between badger vaccination and vaccination for other animal diseases. Risk compensation behaviours are associated with farmers' beliefs as to who should manage animal disease. Rather than farmers' belief in vaccine effectiveness, it is more likely that farmers' low sense of being able to do anything to prevent disease influences their apparent risk compensation behaviours. These findings address the gap in the literature relating to farmers' behavioural adaptions to vaccine use in the management of animal disease.

Network-Based Research on Rural Opioid Use: an Overview of Methods and Lessons Learned

PURPOSE OF REVIEW

The purpose of this paper is to provide a thorough overview of methods used for recruitment, network data collection, and network data management in a network-based study of rural people who use drugs (PWUD) and to offer methodological recommendations for future research on rural drug use.

RECENT FINDINGS

The Social Networks among Appalachian People (SNAP) study recruited a cohort of 503 rural PWUD via respondent-driven sampling (RDS) and has retained more than 80% of eligible participants over 7-9 years. SNAP has yielded important methodological insights, including that (1) RDS referral was non-random and disproportionately involved kin and (2) interviewer-administered questionnaires were successful in eliciting accurate name and age information about network members. The SNAP experience suggests that RDS was a successful recruitment strategy for rural PWUD and questionnaires administered by community-based interviewers in the context of a Certificate of Confidentiality could elicit detailed data on PWUD risk networks.

HIV Vaccine Efficacy Trials: RV144 and Beyond

Despite progress in antiretroviral therapy, pre-exposure prophylaxis, microbicides, and other preventive strategies, a vaccine to prevent HIV-1 infection remains desperately needed. Development of an effective vaccine is challenged by several immunologic features of HIV-1 evidenced by the failure of five of the six HIV-1 candidate vaccine efficacy trials to date. This chapter reviews these efficacy trials with a focus on the Phase 3 RV144 trial in Thailand, the only HIV-1 vaccine efficacy trial to show a moderate protective effect of 31% with respect to placebo administration. Although modest, this protection has allowed for the study of potential immunologic correlates of protection to improve development of future HIV-1 pox-protein and other vaccine strategies. Trials in Thailand and South Africa have built upon the RV144 framework to provide additional immunologic insights which enable current and future efficacy testing of related vaccine candidates.

Latent Risk Subtypes Based on Injection and Sexual Behavior Among People Who Inject Drugs in Rural Puerto Rico

BACKGROUND

People who inject drugs (PWID) in Puerto Rico engage in high levels of injection and sexual risk behavior, and they are at high risk for HIV and hepatitis C (HCV) infection, relative to their US counterparts. Less is known, however, about the clustering of risk behavior conducive to HIV and HCV infection among rural Puerto Rican communities.

OBJECTIVES

The purpose of this study was to examine concurrent injection and sexual risk subtypes among a rural sample of PWID in Puerto Rico.

METHODS

Data were drawn from a respondent-driven sample collected in 2015 of 315 PWID in 4 rural communities approximately 30-40 miles from San Juan. Latent class analysis (LCA) was used to examine risk subtypes using 3 injection and 3 sexual risk indicators. In addition, demographic and other PWID characteristics were examined as possible predictors of latent class membership.

RESULTS

Four LCA subtypes were identified: low risk (36%), high injection/low sexual risk (22%), low injection/high sexual risk (20%), and high risk (22%). Younger age and past year homelessness predicted high risk latent class membership, relative to the other classes. In addition, daily speedball use predicted membership in the high injection/low sexual risk class, relative to the low risk and low injection/high sexual risk classes.

CONCLUSION/IMPORTANCE

The findings suggest ways in which PWID risk clusters can be identified for targeted interventions.

Effect of HIV self-testing on the number of sexual partners among female sex workers in Zambia

Objectives:

To assess the effect of two health system approaches to distribute HIV self-tests on the number of female sex workers’ client and nonclient sexual partners.

Design:

Cluster randomized controlled trial.

Methods:

Peer educators recruited 965 participants. Peer educator–participant groups were randomized 1 : 1 : 1 to one of three arms: delivery of HIV self-tests directly from a peer educator, free facility-based delivery of HIV self-tests in exchange for coupons, or referral to standard-of-care HIV testing. Participants in all three arms completed four peer educator intervention sessions, which included counseling and condom distribution. Participants were asked the average number of client partners they had per night at baseline, 1 and 4 months, and the number of nonclient partners they had in the past 12 months (at baseline) and in the past month (at 1 month and 4 months).

Results:

At 4 months, participants reported significantly fewer clients per night in the direct delivery arm (mean difference −0.78 clients, 95% CI −1.28 to −0.28, P = 0.002) and the coupon arm (−0.71, 95% CI −1.21 to −0.21, P = 0.005) compared with standard of care. Similarly, they reported fewer nonclient partners in the direct delivery arm (−3.19, 95% CI −5.18 to −1.21, P = 0.002) and in the coupon arm (−1.84, 95% CI −3.81 to 0.14, P = 0.07) arm compared with standard of care.

Conclusion:

Expansion of HIV self-testing may have positive behavioral effects enhancing other HIV prevention efforts among female sex workers in Zambia.

Trial Registration:

ClinicalTrials.gov NCT02827240.

Epidemic potential by sexual activity distributions

For sexually transmitted infections like HIV to propagate through a population, there must be a path linking susceptible cases to currently infectious cases. The existence of such paths depends in part on the degree distribution. Here, we use simulation methods to examine how two features of the degree distribution affect network connectivity: Mean degree captures a volume dimension, while the skewness of the upper tail captures a shape dimension. We find a clear interaction between shape and volume: When mean degree is low, connectivity is greater for long-tailed distributions, but at higher mean degree, connectivity is greater in short-tailed distributions. The phase transition to a giant component and giant bicomponent emerges as a positive function of volume, but it rises more sharply and ultimately reaches more people in short-tail distributions than in long-tail distributions. These findings suggest that any interventions should be attuned to how practices affect both the volume and shape of the degree distribution, noting potential unanticipated effects. For example, policies that primarily affect high-volume nodes may not be effective if they simply redistribute volume among lower degree actors, which appears to exacerbate underlying network connectivity.

Relationship-level analysis of drug users' anticipated changes in risk behavior following HIV vaccination

Formative research into the behavioral factors surrounding HIV vaccine uptake is becoming increasingly important as progress is made in HIV vaccine development. Given that the first vaccines on the market are likely to be partially effective, risk compensation (i.e., increased risk behavior following vaccination) may present a concern. This study characterized the relationships in which HIV vaccine-related risk compensation is most likely to occur using dyadic data collected from people who use drugs, a high-risk group markedly underrepresented in extant literature. Data were collected from 433 drug users enrolled in a longitudinal study in the USA. Respondents were asked to provide the first name and last initial of individuals with whom they had injected drugs and/or had sex during the past six months. For each partner, respondents reported their likelihood of increasing risk behavior if they and/or their partner received an HIV vaccine. Using generalized linear mixed models, relationship-level correlates to risk compensation were examined. In bivariate analysis, risk compensation was more likely to occur between partners who have known each other for a shorter time (odds ratio [OR]=0.95, 95% confidence interval [CI]: 0.90-0.99, p=0.028) and between those who inject drugs and have sex together (OR=2.52, CI: 1.05-6.04, p=0.039). In relationships involving risk compensation, 37% involved partners who had known each other for a year or less compared to only 13% of relationships not involving risk compensation. Adjusting for other variables, duration (OR: 0.95, CI: 0.90-1.00, p=0.033) was associated with risk compensation intent. These analyses suggest that risk compensation may be more likely to occur in less established relationships and between partners engaging in more than one type of risk behavior. These data provide further support for the need to expand measures of risk compensation in HIV vaccine preparedness studies to assess not only if people will change their behavior, but also with whom.