Drug Injection-Related Norms and High-Risk Behaviors of People Who Inject Drugs in Athens, Greece

Abstract

Drug use involves social interactions. Therefore, norms in the proximal environment of people who inject drugs (PWID) can favor behaviors that may result in HIV transmission. This work aimed at studying drug injection-related norms and their potential association with risky behaviors among PWID in Athens, Greece, in the context of economic recession and political activism that followed the fiscal crisis and soon after a recent HIV outbreak had leveled off. The Transmission Reduction Intervention Project (TRIP) was a social network-based approach (June 2013 to July 2015) that involved two groups of PWID seeds—with recent HIV infection and with long-term HIV infection and one control group of HIV-negative PWID. Network contacts of seeds were also enrolled. TRIP participants answered a questionnaire that included items on injection-related norms and behaviors. TRIP recruited 320 PWID (HIV positive, 44.4%). TRIP participants, especially those without HIV, often recalled or perceived as normative among their partners and in their networks some behaviors that can lead to HIV transmission. TRIP participants who recalled that they were encouraged by their regular drug partners to use an unclean syringe were almost twice as likely to report that they share syringes [odds ratio (OR) = 2.03; 95% confidence interval (CI) = 1.86–2.21], or give syringes to someone else (OR = 1.70; 95% CI = 1.42–2.04) as those who did not recall such an encouragement. Associations were modified by HIV status. HIV negatives, who were reportedly encouraged to share nonsyringe injecting equipment, were almost 4.5 times as likely to share that material as HIV-negative participants who were not encouraged (OR = 4.59, 95% CI = 4.12–5.11). Further research is needed on the multiple determinants (social, economic, and political) of norms in the social environments of PWID. Since peer norms are associated with risky behaviors, interventions should be developed to encourage norms and peer pressure against the sharing of injection equipment.

Introduction

HIV/AIDS is a public health issue of profound importance with almost 38 million people living with HIV in 2018 worldwide.¹ Approximately 10% of all HIV infections globally and one-third of those outside of Africa are attributed to injection drug use.² Injecting drugs remains a major driver of HIV transmission in countries comprising the former Soviet Union.^3,4 Recently, HIV outbreaks in people who inject drugs (PWID) have been observed in many European countries including Romania, Greece, Ireland, Scotland, and Luxembourg.^5–12 Greece in particular saw an unprecedented increase in HIV diagnoses among PWID between 2011 and 2013, in the context of a serious fiscal and social crisis.^13–16 A large increase in HIV incidence among PWID also occurred in Israel¹⁷ and at least one locality in the United States.^18,19

Behaviors such as condomless sex and especially sharing of injection equipment are associated with increased risk of HIV acquisition among PWID.^20–22 Individual, structural, and social factors can influence these behaviors. Norms are an important element of the social environment. They are often defined as informal understandings of what others typically (i.e., normatively) do or think one should do in a specific setting or social context. Norms can be either descriptive (i.e., perceived normative practices/behaviors in one's social network) or injunctive (i.e., what people think the reaction of most members of their network to their actions would be).²³ Norms as perceptions of other's actions, beliefs, values, or attitudes are key constructs of theoretical frameworks²⁴ and have predicted numerous health-related behaviors (e.g., smoking, alcohol consumption, sexual behavior, exercise, and dietary practices).^25–27

Previous studies in the field of HIV have shown the influence of norms on behaviors among PWID (e.g., injection behaviors) that increase or decrease risk of HIV acquisition. For instance, researchers analyzed baseline data collected from PWID in four cities in the United States and found that HIV-positive participants who perceived that their friends supported safe drug use were less likely to lend their used syringe to HIV-negative people or to people with an unknown HIV status.²⁸ In a longitudinal study of PWID in Baltimore city, USA, the perception of study participants at baseline that risky injection practices were normative among their peers was associated with increased likelihood that study participants at follow-up reported that they shared syringes and other equipment for injecting drugs.²⁹

The focus on norms as “understandings” ignores however, the social process that maintains and changes norms, and thus greatly reduces the extent to which research can contribute to developing effective interventions to reduce risk. In addition, studies on adolescents have shown that perceptual measures of significant others' characteristics reflect features both of the person being perceived and of the perceiver.³⁰

An author of this article (S.R.F.) and other scholars have built from the classical sociological perspective that norms are part of social interaction. They thus developed a way to measure norms as “actions,” which measures the extent to which participants tell us that other people actively objected to their doing something or actively urged them to do it (recalled actual encouragement or objection). Flom et al. first showed that study participants' reports of their peers' normative behavior in a low-income, high drug use neighborhood in New York, such as responses to items on the proportion of close friends who actually encouraged the study participants (young adults) to use specific drugs, were reliable and valid.³¹ They also found that these recalled norms at age 15 predicted drug use at age between 18 and 24 years.³² The same items were used with quite similar results among youth in poor neighborhoods in Buenos Aires in Argentina.³³ They also consist part of the domain of norms in proximal social contexts of a new tool that has been developed to measure pathways between Big Events such as wars, economic hardship, ecological disasters, and so on, and HIV transmission.³⁴

The aims of this article were as follows: (1) to measure drug injection-related norms, as mentioned previously, among PWID in Athens, Greece, in the middle of the economic crisis and while the HIV outbreak was leveling off, and describe them both overall and by intervention group and HIV status; and (2) to study cross-sectional associations between drug injection-related norms and risk behaviors that may result in HIV infection.

Materials and Methods

Description of Transmission Reduction Intervention Project

The Transmission Reduction Intervention Project (TRIP) was a multisite, network-based tracing intervention that has been described in detail elsewhere.^14,35–37 The intervention (ClinicalTrials.gov identifier: NCT01827228) was approved by the Institutional Review Boards of the National Development and Research Institutes (NDRI) in NYC and of the Hellenic Scientific Society for the study of AIDS and Sexually Transmitted Diseases in Athens. In brief, TRIP focused on recently HIV-infected people and their network members, based on the hypothesis that more recently infected people—who are highly infectious—would be found in these networks. TRIP was carried out at the Athens, Greece site between June 2013 and July 2015. People were eligible to participate in TRIP if they were older than 18 years old, spoke Greek or English, consented to HIV testing and to all the procedures of the study, and lived in Athens in the last 12 months.

Recruitment began with a limited number of individuals (seeds) who were either recently HIV-infected or had been infected with HIV for a longer time. Most seeds were referred to TRIP from allied prevention projects. Network contacts of seeds were enrolled in two steps from each seed, unless a new recent infection was found in the networks in which case network tracing continued for two additional steps. All network contacts were tested for HIV infection. HIV testing was carried out using a microparticle enzyme anti-HIV-1/2 immunoassay (AxSYM HIV-1/2 gO; Abbott). Reactive samples were confirmed by a western blot method (MP Diagnostics). Recent HIV infections were detected with the Limiting Antigen Avidity (LAg) assay (Sedia™; Biosciences Corporation).^38,39 HIV-negative PWID referred to TRIP from allied projects served as an HIV-negative control group.

Based on HIV status, testing history, and LAg results, TRIP participants were classified into five groups: (1) recent seeds (RS) (HIV infection was acquired <6 months ago); (2) control seeds with long-term HIV infection (HIV infection occurred >6 months ago) (LCS); (3) network members of RS; (4) network members of LCS; and (5) HIV-negative controls (control group without HIV infection).

Norms and behaviors variables

TRIP participants who reported injecting drugs completed a structured questionnaire that included items on drug injection-related norms and on their drug injecting and sexual behaviors. Norms items were taken from tools presented elsewhere.^31,34 Exact questions (Q) and responses (R) about norms and behaviors that were considered in this analysis are given in Figure 1 and in the Supplementary Data (Supplementary Table S1).

FIG. 1.

Questions and responses for norms and behaviors that were included in the questionnaire of the TRIP. TRIP, Transmission Reduction Intervention Project. Color images are available online.

Statistical methods

Descriptive analyses included the calculation of frequencies and percentages for categorical variables and of mean, median, and interquartile range (IQR) for continuous variables. Univariate analyses involved chi-squared tests and t-tests. Logistic and linear regression models with cluster-robust standard error estimators (cluster: TRIP groups) were used to examine associations between norms and behaviors. Multivariate models adjusted for potential confounders (sociodemographic and other characteristics including gender, age, nationality, education level, accommodation status, and HIV status). Interaction terms were inserted in multivariate analyses to explore the potential role of HIV status as effect modifier. Bonferroni correction and false discovery rate test were used to address the problem of multiple comparisons.

For descriptive analyses, the questionnaire responses were collapsed into fewer categories. Five-point scales were merged into three categories [none; few/about half; most/all—disagree strongly; disagree somewhat/neither disagree nor agree/agree somewhat (i.e., neutral); agree strongly]. Seven-point scales were collapsed into four categories (none; very few/less than half; about half/more than half; almost all/all). For multivariate analyses, all norms and behavior variables but Q18 (number of different people a participant injected with during the past 6 months) were modeled as dichotomous (risky vs. safe norms or risky vs. safe behavior) to facilitate logistic regression analysis.

The level of significance was set to p < .05. The statistical analyses were conducted in STATA 14 (Stata Corp., USA).

Results

Participants' characteristics

A total of 320 PWID (median age = 34 years, IQR = 30–40; men = 257, 80.3%) participated in TRIP (Table 1). Of these, 22 were RS, 19 were long-term control seeds, 141 were network members of RS, 59 were network members of LCS, and 79 were HIV-negative controls. Most PWID were of Greek nationality (291, 90.9%), nearly a fifth (74, 23.1%) lacked stable accommodation, and nearly half were HIV positive (142, 44.4%). The median duration of drug injection was 13 years (IQR = 7–18).

Table 1.

Sociodemographic Characteristics of People Who Inject Drugs (N = 320) and Were Recruited in the Transmission Reduction Intervention Project in Athens, Greece, 2013–2015

Sociodemographic characteristics	Total	RS	Control seeds with long-term HIV infection (LCS)	Network of RS	Network of LCS	HIV negative controls	p
Total, N (%)	320 (100)	22 (6.9)	19 (5.9)	141 (44.1)	59 (18.4)	79 (24.7)	—
Gender, n (%)
Males	257 (80.3)	17 (77.3)	16 (84.2)	115 (81.6)	46 (78.0)	63 (79.8)	.96
Females	63 (19.7)	5 (22.7)	3 (15.8)	26 (18.4)	13 (22.0)	16 (20.2)
Median age, years (IQR)	34 (30–40)	36 (30–43)	36 (32–40)	35 (30–40)	33 (30–36)	34 (31–45)	.11
Nationality, n (%)
Greek	291 (90.9)	21 (95.4)	17 (89.5)	122 (86.5)	53 (89.8)	78 (98.7)	.04
Non-Greek	29 (9.1)	1 (4.6)	2 (10.5)	19 (13.5)	6 (10.2)	1 (1.3)
Residents of Athens (since birth), n (%)
Permanent	183 (57.2)	11 (50.0)	12 (63.2)	76 (53.9)	29 (49.2)	55 (69.6)	.10
Nonpermanent	137 (42.8)	11 (50.0)	7 (36.8)	65 (46.1)	30 (50.8)	24 (30.4)
Education level, N (%)
Up to high school	282 (88.1)	20 (90.9)	16 (84.2)	125 (88.6)	51 (86.4)	70 (88.6)	.96
Above high school	38 (11.9)	2 (9.1)	3 (15.8)	16 (11.4)	8 (13.6)	9 (11.4)
Accommodation status in past 6 months, N (%)
Nonhomeless	246 (76.9)	17 (77.3)	15 (79.0)	101 (71.6)	39 (66.1)	74 (93.7)	<.01
Homeless	74 (23.1)	5 (22.7)	4 (21.0)	40 (28.4)	20 (33.9)	5 (6.3)
Employment, N (%)
Employed	49 (15.3)	4 (18.2)	4 (21.0)	17 (12.1)	8 (13.6)	16 (20.2)	.49
Unemployed/unable to work	271 (84.7)	18 (81.8)	15 (79.0)	124 (87.9)	51 (86.4)	63 (79.8)
HIV status, n (%)
HIV negative	178 (55.6)	0	0	77 (54.6)	22 (37.3)	79 (100)	<.01
HIV positive	142 (44.4)	22 (100)	19 (100)	64 (45.4)	37 (62.7)	0
Duration of injection, years (IQR)a	13 (7–18)	12.5 (3–19)	12 (7–16)	12 (6–17.5)	13 (7–15)	14.5 (8–20)	.26
Drug/alcohol treatment status at enrollment in TRIP, n (%)
Not on treatment	194 (60.6)	14 (63.6)	13 (68.4)	89 (63.1)	37 (62.7)	41 (51.9)	.47
On treatment	126 (39.4)	8 (36.4)	6 (31.6)	52 (36.9)	22 (37.3)	38 (48.1)
Sexual orientation, n (%)b
Homosexual	8 (2.5)	1 (4.6)	1 (5.3)	3 (2.1)	1 (1.7)	2 (2.5)	.88
Heterosexual	311 (97.5)	21 (95.4)	18 (94.7)	137 (97.9)	58 (98.3)	77 (97.5)
Sex workers, n (%)
Malesc	8 (3.1)	1 (5.9)	0 (0.0)	2 (1.7)	3 (6.5)	2 (3.2)	.49
Femalesd	23 (35.9)	0 (0.0)	2 (66.7)	12 (46.2)	8 (61.5)	1 (5.9)	<.01
Total	31 (9.7)	1 (4.6)	2 (10.5)	14 (9.9)	11 (18.6)	3 (3.8)	.06

Bold font indicates statistical significance (p < 0.05).

^an = 317.

^bn = 319.

^cn = 257 (cis males).

^dn = 64 (cis females and a trans female).

IQR, interquartile range; LCS, long-term control seeds; RS, recent seeds; TRIP, Transmission Reduction Intervention Project.

Social norms

Norms questions on recalled actual encouragement of injection practices

The majority of TRIP respondents (64.8%) answered “none” to Q1 on the proportion of people TRIP participants regularly injected with in the past 6 months who actually encouraged the participants to use a syringe someone else had already used (i.e., this safe behavior was the norm among this sample). For Q2 (i.e., injecting equipment other than syringes), around half of TRIP PWID (47.9%) said that none of the people they injected with in the past 6 months encouraged them to use cooker, filter, or rinse water someone else had used before (Supplementary Table S2).

The distribution of responses to Q1 and Q2 did not vary significantly between TRIP groups (Supplementary Table S2) or by HIV status (Supplementary Table S3).

Norms questions on recalled actual encouragement or objection at drug-using venues

Around a third of TRIP PWID (27.5%) indicated in Q3 that people at venues where they hang out to meet drug partners never encouraged others to use an available sterile syringe (Fig. 2; Supplementary Table S2). This percentage was a bit higher (37.3%) when the question (Q5) referred to cookers, filters, and rinse water (Supplementary Table S2 and Supplementary Fig. S1). Of interest, this pattern that does not promote safe behaviors was significantly more common or even normative among people at the venues of HIV-negative control participants (Q3, 42.5%, p = .04; Q5, 57.5%, p = .02). In analyses by HIV status (Supplementary Table S3), all HIV-negative participants in TRIP were also more likely than HIV-positive participants to answer “none of the occasions” to questions Q3 (31.6% vs. 22.2%, respectively, p = .11) and Q5 (43.9% vs. 28.9%, respectively, p < .01).

FIG. 2.

Responses to norms questions Q3 (p = .04) and Q4 (p < .01) on recalled actual encouragement or objection at drug-using venues (occasions the participant injected with two or more others) in the TRIP. LCS, long-term control seeds; RS, recent seeds. Color images are available online.

Similar patterns were observed in questions 4 and 6 (Fig. 2; Supplementary Tables S2 and S3; Supplementary Fig. S1).

Norms questions on conjectured objection under different conditions, that is, in withdrawal or not in withdrawal (injunctive norms)

Questions 7, 8, and 9 measure perceived norms about the acceptability among injection network members of TRIP participants who are in withdrawal of their sharing injecting equipment with HIV-positive people or other ill people (Fig. 3; Supplementary Table S4). Overall, nearly half of TRIP PWID reported perceiving that safe behavior was normative among the people with whom they inject: they strongly agreed that people they inject with would disapprove their sharing of a syringe with an HIV-infected person (Q7, 51.3%) or with dirty/sickly people (Q9, 54.4%). The proportion of people who perceived safe behavior to be normative fell considerably when asked about sharing with an HIV-negative person (Q8, 30.9%). Perceptions that safe behaviors were normative were less prevalent among the network members of LCS and HIV-negative control participants.

FIG. 3.

Responses to norms questions Q7 (p < .01) and Q8 (p < .01) on conjectured objection when participants in the TRIP are in withdrawal. Color images are available online.

In particular, the answer “strongly agree” that network members would object to participant's sharing of a syringe with an HIV-positive person (Q7) was significantly less common (p < .01) among the network members of LCS (33.3%) and the HIV-negative control participants (44.4%). When TRIP participants were asked about sharing with an HIV-negative person (Q8), the proportion who perceived that safe behavior was normative was even lower (p < .01) in these groups (10.5% among network members of LCS and 26.4% among HIV-negative control participants). Analyses by HIV status did not find any significant differences (p > .05) in responses to questions Q7–Q9 (Supplementary Table S5).

Responses to questions 10, 11, and 12 that are identical to Q7–Q9 but refer to when TRIP participants did not encounter a withdrawal problem were very similar (Supplementary Tables S4 and S5; Supplementary Fig. S2).

Moreover, with some differences, quite similar response patterns were observed in questions 13, 14, and 15 that asked TRIP participants about how people they inject with would react (object) if TRIP participants gave their used syringe to a person who is or about to be in withdrawal (Supplementary Table S4; Fig. 4). However, there were differences between participants with and without HIV. Those with HIV were significantly more likely than participants without HIV to agree that people they inject with would object to giving their syringes to someone else who is or about to be in withdrawal (Supplementary Table S5).

FIG. 4.

Responses to norms questions Q14 (p = .04) and Q15 (p = .04) on conjectured objection when participants in the TRIP are in withdrawal. Color images are available online.

Association between drug injection-related norms and behaviors

Supplementary Tables S6 and S7 in the supplementary material present the results of univariate and multivariate logistic and linear regression models, clustered by TRIP group, on the association between drug injection-related norms and behaviors. Unadjusted and adjusted models for drug injection-related norms and sexual behaviors are also presented in the Supplementary Data (Supplementary Tables S8 and S9).

Participants who were encouraged by their regular drug partners to share a syringe (Q1) were almost twice as likely as those who were not encouraged to report sharing of a used syringe [Q19, adjusted odds ratio (aOR) = 2.03, 95% confidence interval (CI) = 1.86–2.21] or other injecting material (Q21, aOR = 1.83, 95% CI = 1.09–3.08) and of giving a syringe they have already used to someone else (Q20, aOR = 1.70, 95% CI = 1.42–2.04). Similar patterns of behaviors (Q19, aOR = 1.95, 95% CI = 1.42–2.67; Q20, aOR = 2.68, 95% CI = 2.13–3.38; Q21, aOR = 3.37, 95% CI = 2.34–4.86) were observed for participants who were encouraged to share a cooker, filter, or rinse water (Q2) compared with those who were not encouraged. These associations remained statistically significant following Bonferroni correction or the use of the false discovery rate test (Supplementary Table S10).

HIV status seems to act as effect modifier (Supplementary Tables S11–S14). For instance, participants who were encouraged to share a cooker, filter, or rinse water (Q2) were more than two times as likely (Q21, aOR = 2.41, 95% CI = 1.17–4.99) as those who were not encouraged, to share injecting material other than syringes when they were HIV-positive but more than four times as likely (Q21, aOR = 4.59, 95% CI = 4.12–5.11) when they were HIV negative.

Discussion

TRIP examined norms related to drug injection and their relationship with behaviors that put PWID at risk for HIV. Although the HIV outbreak in Athens, Greece was successfully controlled, it seems that some risky behaviors probably remained normative among PWID. Furthermore, risky behaviors seemed to be more normative among certain TRIP groups, such as the HIV-negative control participants and those in the networks of LCS. Actions of people TRIP participants regularly injected with, rather than of people at drug-using settings, such as encouragement to use injecting material someone else has used before, significantly increased the probability that TRIP participants reported that they had engaged in injecting practices like sharing of syringes, cooker, filters, or rinse water. This association was modified by the HIV status of the participants.

In terms of associations between norms and behaviors, our work corroborates the findings of previous research, mostly in the United States. In the early years of the epidemic, Friedman et al. reported that PWID were more likely to endorse protective practices if their acquaintances also protected themselves.⁴⁰ Another study in New York City also showed that peer group behavior (drug injection) was a correlate of needle sharing.⁴¹ In another study of PWID in the United States, intention to bleach needles/syringes and frequency of bleaching were associated with normative pressure by important others.⁴²

Recalled peers' actual encouragement of and conjectured objection to drug use were significant predictors of current drug use in an impoverished urban context in New York City with widespread use of drugs.³² In four U.S. cities, HIV-positive PWID who reported supportive norms for safe drug use were less likely to give their needles/syringes to an HIV uninfected person or someone with an unknown HIV status.²⁸ Another study in five U.S. cities enrolled PWID of young age (15–30 years old) and explored factors associated with syringe sharing. The participants of that study were more likely to report receptive or distributive syringe sharing when they perceived that their peers would not disapprove these practices.^43,44 In the same study, having friends who shared also predicted participants' sharing of nonsyringe injecting equipment.⁴⁵ Cross-sectional data from PWID in Baltimore, USA showed that male needle sharers reported higher scores of descriptive and injunctive norms that favored risky behaviors. In women, needle sharing was associated only with descriptive norms.⁴⁶ Longitudinal analyses from the same population confirmed the predictive ability of descriptive norms in terms of sharing of syringes and other injecting paraphernalia.²⁹

It is of interest to note that, in our analysis, norms among regular drug partners rather than among people at drug-using venues were mostly correlates of sharing. It seems that, at least for injection-related behaviors that can lead to HIV transmission, PWID are perhaps more influenced or persuaded by people who they regularly inject drugs with than by family members, nondrug-using partners, or even persons they inject with at drug-using settings. Moreover, there are several dimensions of norms that may influence behaviors. Violating one norm may not be perceived as important as violating other norms. By expanding measurement to many items, we think that several dimensions of drug injection-related norms were captured.

It seems that riskier behaviors were more likely to be normative among the networks of HIV-negative people. This looks counterintuitive as someone would expect that if norms predict behaviors, safe behavioral patterns will be the norm in the networks of people who remained HIV free. On the contrary, one would argue that the relationship between norms and behaviors is bidirectional. Thus, in networks where HIV is prevalent, people gradually change their behavior as a response to interventions or in the context of community action and safer behaviors become normative.⁴⁷ In any case, this finding is important from a public health point of view and emphasizes the need for continuous prevention interventions even when the prevalence of HIV is low among PWID networks to prevent future HIV outbreaks.¹²

Another interesting finding of the analyses was that PWID were more likely to strongly agree that people in their network would approve their sharing of injection material with someone who is HIV negative rather than with someone who is HIV positive or looks dirty. Similarly, people in the participants' networks were reportedly less likely to object to the participants' giving of injecting equipment to someone with HIV or who looks dirty than to someone who is HIV negative. Misconceptions about HIV risk based on physical appearance are still prevalent among PWID in Greece. Public health policies including health education programs, community outreach education to PWID community, and convenient HIV counseling and testing are necessary to confront misconceptions and help PWID understand that recommended precautions should be universal regardless of the HIV status of one's contacts.¹²

Big events like wars, natural disasters, economic crises, political instability, political–economic transitions, and other similar phenomena are spread worldwide and have unleashed HIV outbreaks, especially among PWID, in Russia, Ukraine, and New York City in the past.^14,48,49 Some scales and indexes to measure how Big Events affect HIV risk including those that focus on normative pressure in people's proximal social environment have been investigated and validated in a population of PWID in New York City.³⁴ This is the first time that a subset of these measures that reflect normative patterns has been used in a European country (Athens, Greece). Our results could serve as a baseline for comparisons with data from future studies with the appropriate design to explore the relationship between Big Events, norms, and behaviors.

Certain limitations of this analysis should be recognized. The study was cross-sectional and time-order could not be established. This does not allow us to draw causal inference. Norms and behaviors were based on self-report and were likely to be under-reported or affected by social desirability bias, which may depend on HIV status and on how long someone has been infected. Recalled norms may also be biased toward current norms. The sample was not a probability one and thus perhaps not representative of the PWID population, which limits the degree to which the findings of this analysis can be generalized. The statistical analyses should also be viewed with caution given the nature of recruitment in social network-based studies, which may violate the assumption of independence of observations. The use of cluster-robust standard errors probably reduces this unwanted effect. Finally, multiple comparisons could lead to significant results purely owing to chance. However, many statistically significant associations remained following Bonferroni correction.

Conclusions

In summary, some risky behaviors are normative among PWID, and especially among those without HIV, in Athens, Greece, although an HIV outbreak that followed the economic crisis was largely contained. This raises issues of concern for reoccurrence of rapid HIV transmission and the necessity to continue prevention interventions in this population. Further research is needed on the multiple determinants (social, economic, and political) of norms in the social environments of PWID. The association between drug injection-related norms and injecting behaviors supports the conduct of peer-based interventions that focus on promoting safe behaviors for PWID, on strengthening their links with persons who behave in a safe manner, and on efforts to shift or build norms among their partners, friends, and family members in the direction of risk reduction.

Ethical Approval

All procedures performed in this study were in accordance with the ethical standards of the institutional and/or national research committee and with the 1964 Declaration of Helsinki and its later amendments or comparable ethical standards.

Informed Consent

Informed consent was obtained from all individuals participated in TRIP.

Author Disclosure Statement

No competing financial interests exist.

Funding Information

The study was supported by the United States National Institute on Drug Abuse (NIDA) (DP1 DA034989), the Hellenic Scientific Society for the study of AIDS and Sexually Transmitted Diseases (STDs), and the 2018 Asklepios Gilead Hellas Grants Programme.

Supplementary Material

Supplementary Figure S1

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Supplementary Table S1

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Supplementary Table S14