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Differences in Awareness of Pre-exposure Prophylaxis and Post-exposure Prophylaxis Among Groups At-Risk for HIV in New York State: New York City and Long Island, NY, 2011–2013

Walters, Suzan M. MA*; Rivera, Alexis V. MPH; Starbuck, Lila MPH; Reilly, Kathleen H. PhD; Boldon, Nyasha MA, MPH; Anderson, Bridget J. PhD§; Braunstein, Sarah PhD

Author Information
JAIDS Journal of Acquired Immune Deficiency Syndromes: July 1, 2017 - Volume 75 - Issue - p S383-S391
doi: 10.1097/QAI.0000000000001415

Abstract

Erratum

In the article by Walters et al, appearing in JAIDS: Journal of Acquired Immune Deficiency Syndromes , Vol. 75 (suppl 3), pp. S383-S391 entitled, Differences in Awareness of Pre-exposure Prophylaxis and Post-exposure Prophylaxis Among Groups At-Risk for HIV in New York State: New York City and Long Island, NY, 2011–2013, the wrong version of Figure 1 was published. The correct version of Figure 1 appears below.

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JAIDS Journal of Acquired Immune Deficiency Syndromes. 77(1):e13, January 1, 2018.

INTRODUCTION

The use of antiretroviral therapy to prevent HIV, known as preexposure prophylaxis (PrEP), has offered promise in reducing HIV infections.1–4 In 2015, more than 1.2 million persons aged 13 and older were living with HIV in the United States (U.S.), with 1 of 8 unaware of their positive status. Of new diagnoses, 67% of new diagnoses were attributed to men who have sex with men (MSM) contact, 24% to heterosexual contact, and 6% to injection drug use (some 3% of new infections occurred among MSM who injected drugs). HIV continues to spread in the U.S., disproportionally impacting underserved communities, especially people of color, and increasing health disparities.5

Prescribing HIV postexposure prophylaxis (PEP) after an occupational exposure or nonoccupational exposure has been recommended for over a decade. In 2005, the Centers for Disease Control and Prevention (CDC) released recommendations for administering PEP.6 Both PrEP and PEP act as biomedical interventions that provide additional HIV prevention options beyond traditional measures for individuals at-risk.

Interim guidance to health care providers for administering PrEP to MSM was provided by the CDC in 2011.7 After, in 2012, the Food and Drug Administration announced the approval of the fixed dose formulation of emtricitabine and tenofovir disoproxil fumarate as Truvada “to reduce the risk of HIV infection in uninfected individuals who are at high risk of HIV infection and who may engage in sexual activity with HIV-infected partners.”8 In August 2012, the CDC released interim guidance for PrEP among heterosexually active adults9 and in 2013 the CDC released guidelines for injection drug users (IDU).10

New York State (NYS) is an important area to direct prevention efforts. In 2012, 10% of new HIV diagnoses reported in the United States occurred among NYS residents, NYS was ranked second in the nation for AIDS diagnoses,11 and NYS was fourth in number of HIV diagnoses reported in 2013.12 In 2014, NYS Governor Andrew M. Cuomo announced a 3-point plan for “Ending the Epidemic”. The initiative sought to (1) identify undiagnosed HIV cases; (2) link and retain persons living with HIV to care; and (3) provide people at high risk for acquiring HIV, access to PrEP.13 Moreover, in 2015, the White House released an updated National HIV/AIDS Strategy for the United States, which highlighted PrEP as a key HIV prevention tool. The update identified access to PrEP as a priority, stating that there should be a focus on “full access to comprehensive PrEP services for those whom it is appropriate and desired.”14

Despite these commitments, little is known about awareness and perceptions of PrEP within at-risk communities beyond MSM. Few studies have addressed PrEP awareness, and virtually no studies have compared awareness among individuals with differential risks.15 Studies of PrEP/PEP tend to focus solely on MSM.16–22 However, studies examining other risk groups have shown low or more limited awareness among females23 and people who inject drugs.24,25

Within the literature on PrEP/PEP awareness, a positive HIV status has been associated with greater awareness.19,26 Some studies have shown associations between PrEP/PEP awareness and noninjection drug use,18 whereas others have not indicated a relationship.26,27 Furthermore, research has also pointed to racial disparities in awareness and access.22,27 Last, 1 study looking at awareness of both PrEP and PEP found awareness to be higher for PEP (41%) than that for PrEP (21%).20

In this study, we sought to fill the gap in research by identifying NYS regional differences in awareness, differences between at-risk groups and to identify associations with awareness. Examining awareness at the point in history when PrEP was introduced is critical for identifying means of awareness dissemination.

METHODS

This analysis used data collected by the National HIV Behavioral Surveillance (NHBS) system, a cross-sectional survey that rotates annually among 3 populations at-risk for HIV: MSM, people who inject drugs (also referred to as the IDU cycle), and heterosexuals living in high-prevalence areas for poverty and HIV (HET). During 2011–2013, the years of data collection used in this analysis, NHBS was conducted in 20 cities. Data for this analysis was from the Nassau-Suffolk, NY (ie, Long Island) and the New York City (NYC), NY project areas. The analysis includes data collected during the 2011 MSM cycle, 2012 IDU cycle, and 2013 HET cycle. MSM were recruited using a venue-based time-space sampling method, which involves the identification of spaces (venues), times, and methods for recruitment.28 Respondent-driven sampling (RDS) was used during the HET and IDU cycles. RDS is a peer-driven, chain-referral sampling method.29 The NHBS protocol, methodology, and questionnaire were reviewed and approved by sites local Institutional Review Boards.

Anonymous and incentivized interviews were conducted face-to-face using CDC provided standard NHBS questionnaires. Consenting and eligible participants were interviewed and offered anonymous HIV testing, with test results returned after the survey. NHBS eligibility requirements included being 18 years or older (except for the HET cycle where eligible ages ranged from 18 years to 60 years), being able to take the survey in English or Spanish, residing in the respective MSA, and meeting cycle-specific requirements. Cycle-specific eligibility criteria for the MSM cycle included that participants had been born male, self-identified as male, and reported ever having oral or anal sex with a man. Both the HET and IDU cycles required a valid coupon for RDS sampling. The IDU cycle allowed for transgender persons to be surveyed, but they were excluded from this analysis because of small numbers. In addition, eligibility criteria for the IDU cycle required participants to have injected drugs without a prescription within the last 12 months. For the HET cycle, additional seed (initial recruits) criteria included that seeds be residents of high-risk areas, had not recently injected drugs, reported a low socioeconomic status, and had vaginal or anal sex with an opposite sex partner within the last 12 months. To guard against error data was coded so that there were no overlaps between groups (MSM that indicated injection drug use within the last 12 months were identified and excluded from the analysis. For the heterosexual category, we excluded males who were identified as gay. In addition, if a participant (male or female) in the MSM or HET cycle indicated they injected drugs in the last 12 months they were excluded).

Measures

Outcome Variable

Participants were asked 1 of 2 questions depending on their self-reported HIV status: “Before today, have you ever heard of people who do not have HIV taking antiretroviral medicines, to keep from getting HIV?” or “Before today, have you ever heard of people who do not have HIV taking anti-HIV medicines, to keep from getting HIV?” The term “anti-HIV medicines” was used for self-reported HIV-negative persons because they may not be familiar with the term “antiviral medicines.” These questions, used to measure awareness of PrEP/PEP, were combined into 1 binary variable for analysis.

Independent Variables

The main independent variable of interest was risk group. Since the MSM cycle did not contain females, to control for sex, the HET and IDU cycles were split into 2 variables each. This created 5 unique cycle/gender variables: MSM, female IDU, male IDU, female HET, and male HET. Controls for age, education, household income, reported noninjection cocaine and heroin use, current HIV status, and mutually exclusive race/ethnicity were included [If a person indicated Hispanic or Latino heritage, they were coded as Hispanic/Latino (subsequently identified as Latino in this paper)]. Because research indicates that in the United States, the Black/African American experience is unique from other racial categories, participants were coded Black/African American (subsequently identified as Black) if they indicated non-Latino and Black or African American ancestry.30 Last, a white/multiracial/other category was created due to small numbers in the multiracial and other categories. (The white/multiracial/other included white participants with Alaska Natives, Asians, and/or American Indians).

Exposure to HIV prevention professionals and services where participants could potentially learn about PrEP/PEP were measured by the question, “In the past 12 months, have you had a one-on-one conversation with an outreach worker, counselor, or prevention program worker about ways to prevent HIV? Don't count the times when you had a conversation as part of an HIV test.”

Analysis

The analysis tested the hypothesis that MSM would report higher awareness of PrEP/PEP than other at-risk groups for HIV. First, descriptive statistics by cycle and sex were calculated. Second, bivariate analyses, using chi-squared statistics, were conducted to examine correlates of PrEP/PEP awareness with identified variables. During this stage, health care, insurance, and noninjection drug use variables were assessed. Variables that were not significant were excluded from the analysis. Third, we created multivariate models using binary logistic regression.31 We first conducted bivariate regressions (Table 3, model 1; Table 4, model 1) with risk group on PrEP/PEP awareness. Additional variables were then added one by one to the multivariate model. On Long Island, an interaction term for Black MSM was added to examine the relationship between race and risk group. In NYC an interaction for MSM and ages 18–29 years was added (all possible interactions for risk group, age, and race were tested for both NYC and Long Island). Analyses were conducted using STATA 14 and SAS 9.3.

RESULTS

A total of 2483 participants were included in our sample (1455 from NYC and 1028 from Long Island). Figure 1 displays the percent of all participants who reported awareness of PrEP/PEP by NHBS cycle. Overall, PrEP/PEP awareness was low. Of the 1455 participants in NYC, 221 (15%) reported PrEP/PEP awareness. On Long Island, of the 1028 participants, 98 (9.5%) reported awareness. The MSM cycle, sampled in 2011, had more PrEP/PEP awareness than other risk groups in each region; 25% in NYC and 16% on Long Island.

FIGURE 1.
FIGURE 1.:
Knowledge of PREP/PEP by risk group: New York City and Long Island, NHBS 2011–2013 Note: MSM data collected in 2011, IDU data collected in 2012, and HET data collected in 2013.

New York City, NY

In NYC (Table 1) the study sample consisted of 486 MSM, 468 IDU [122 (26%) female], and 501 HET [207 (41%) female]. Awareness of PrEP/PEP was low, with MSM reporting higher awareness; 25% MSM, 12% female IDU, 9% male IDU, 10% female HET, and 12% male HET. Over half of the MSM sample (54%) was aged 18–29 years. By contrast, a large portion of IDU and HET were aged 40 years or older; 71% female IDU, 66% male IDU, 50% female HET, and 57% male HET. MSM were 39% Latino, 37% white, and 23% Black. The IDU sample was predominantly Latino (52% female and 66% male), followed by Black. Whereas the HET sample was mostly Black (73% female and 65% male), followed by Latinos.

TABLE 1.
TABLE 1.:
Descriptive Statistics by Cycle and Sex, NHBS New York City, NY (2011–2013)

The MSM sample was more educated. All but 9% of MSM had a high school degree or higher. Conversely, 48% IDU and 36% HET had less than a high school degree. Similarly, MSM had higher household income compared with IDU and HET. HIV-positive test results were low, with the highest rate among MSM; 89 (18%) MSM, 56 (12%) IDU, and 17 (3%) HET tested positive. For noninjection cocaine use, all groups reported around 20%. MSM reported much lower noninjection heroin use (1%) compared with 28% female IDU, 22% male IDU, 19% female HET, and 21% male HET. Last, 19% MSM, 25% female IDU, 24% male IDU, 20% female HET, and 26% male HET reported exposure to HIV prevention professionals.

Long Island, NY

On Long Island (Table 2), the study sample consisted of 307 MSM, 196 IDU (32% female), and 525 HET (48% female). MSM reported higher PrEP/PEP awareness; 16% MSM, 8% female IDU, 7% male IDU, 6% female HET, and 7% male HET. A large portion of the MSM cycle (49%) was aged 18–29 years. IDU and HET were older with 68% female IDU, 46% male IDU, 46% female HET, and 47% male HET aged 40 years or older. MSM were mostly white (70%) followed by Latinos (22%) then Blacks (8%). IDU and HET were predominantly Black (56% female IDU, 55% male IDU, 81% female HET, and 84% male HET). All but 3% of the MSM sample had a high school degree or higher. Conversely, 22% of IDU and 24% of HET had less than a high school degree.

TABLE 2.
TABLE 2.:
Descriptive Statistics by Cycle and Sex, NHBS Long Island, NY (2011–2013)

MSM had higher household income compared with IDU and HET. For noninjection cocaine use, IDU reported the highest use (46% female IDU and 52% male IDU) compared with MSM (22%) and HET (female HET were reported 13% and male HET reported 17%). As in NYC, Long Island MSM reporting much lower noninjection heroin use (less than 1%) compared with the other groups (41% female IDU, 53% male IDU, 6% female HET, and 13% male HET). There were few positive HIV test results, with the largest number among IDU; 8 (3%) MSM, 13 (7%) IDU, and 6 (1%) HET. Last, 20% MSM, 36% IDU, and 11% HET reported exposure to HIV prevention professionals.

New York City, NY

In bivariate logistic regression (Table 3, model 1), female IDU, male IDU, female HET, and male HET had significantly decreased odds of PrEP/PEP awareness compared with MSM. When controlling for race, household income, education, age, HIV status, noninjection drug use, and exposure to HIV prevention professionals (Table 3, model 2), all groups remained with significant decreased odds of PrEP/PEP awareness compared with MSM. Male IDU had 64% decreased odds [AOR: 0.36; 95% confidence interval (CI): 0.21 to 0.63], female IDU had 52% decreased odds (AOR: 0.48; 95% CI: 0.24 to 0.96), male HET had 42% decreased odds (AOR: 0.58; 95% CI: 0.34 to 0.99), and female HET had 47% decreased odds (AOR: 0.53; 95% CI: 0.28 to 0.98) of PrEP/PEP awareness.

TABLE 3.
TABLE 3.:
Logistic Regression Estimating Awareness of PrEP and PEP: New York City, NY (2011–2013)

Exposure to HIV prevention professionals was significant, meaning that participants who had spoken to a professional about HIV prevention had 66% higher odds of PrEP/PEP awareness (AOR: 1.66; 95% CI: 1.18 to 2.35) than those who did not. Participants who tested HIV positive had 62% increased odds, compared with HIV-negative participants, of having PrEP/PEP awareness (AOR: 1.62; 95% CI: 1.04 to 2.54). Noninjection cocaine and heroin use was associated with greater odds of awareness; 75% increase in odds for those reporting noninjection cocaine use (AOR: 1.75; 95% CI: 1.22 to 2.51) and 69% increased odds for those reporting noninjection heroin use (AOR: 1.69; 95% CI: 1.03 to 2.75). Household income was associated with increased odds of PrEP/PEP awareness (AOR: 1.42; 95% CI: 1.19 to 1.69). Race, age, and education were not significantly associated with PrEP/PEP awareness.

The final model included an interaction between MSM and age (Table 3, model 3), indicating that MSM aged 18–29 years had 194% increased odds of PrEP/PEP awareness (AOR: 2.94; 95% CI: 1.11 to 7.80). In addition, the variable for ages 18–29 years became significant, indicating that IDU and HET aged 18–29 years old had 71% decreased odds of PrEP/PEP awareness (AOR: 0.29; 95% CI: 0.12 to 0.72).

Male IDU had significantly decreased odds (55%) of PrEP/PEP awareness (AOR: 0.45; 95% CI: 0.25 to 0.81). Female HET, male HET, and female IDU remained with decreased odds, but not at a significant level. Reported noninjection cocaine use had 74% increased odds of awareness (AOR: 1.74; 95% CI: 1.21 to 2.49). Last, household income (AOR: 1.45; 95% CI: 1.22 to 1.73), exposure to HIV prevention professionals (AOR: 1.61; 95% CI: 1.13 to 2.27), and having a positive HIV test (AOR: 1.66; 95% CI: 1.07 to 2.60) remained significant.

Long Island, NY

In bivariate logistic regression (Table 4, model 1), IDU and HET had statistically decreased odds of PrEP/PEP awareness compared with MSM. When controls were added (Table 4, model 2), all groups remained with decreased odds of PrEP/PEP awareness compared with MSM. Female IDU had 74% decreased odds (AOR: 0.26; 95% CI: 0.07 to 0.90), male IDU 80% decreased odds (AOR: 0.20; 95% CI: 0.07 to 0.57), female HET 68% decreased odds (AOR: 0.32; 95% CI: 0.13 to 0.75), and male HET 60% decreased odds (AOR: 0.40; 95% CI: 0.17 to 0.93) of PrEP/PEP awareness.

TABLE 4.
TABLE 4.:
Logistic Regression Estimating Awareness of PrEP and PEP: Long Island, NY (2011–2013)

The final model included an interaction term for Black MSM (Table 4, model 3), yielding over 4 times the predicted odds of reported PrEP/PEP awareness (AOR 4.08; 95% CI: 1.21 to 13.73). Said otherwise, Black MSM compared with HET and IDU with identical demographical profiles had 308% increased odds of PrEP/PEP awareness.

Furthermore, all risk groups remained with decreased odds of PrEP/PEP awareness compared with those of MSM. Female IDU had 82% decreased odds (AOR: 0.18; 95% CI: 0.05 to 0.62), male IDU had 86% decreased odds (AOR: 0.14; 95% CI: 0.05 to 0.39), female HET had 75% decreased odds (AOR: 0.25; 95% CI: 0.11 to 0.59), and male HET had 68% decreased odds (AOR: 0.32; 95% CI: 0.14 to 0.73) of PrEP/PEP awareness compared with those of MSM. Having a positive HIV test was associated with 633% increased odds of reported PrEP/PEP awareness (AOR: 7.33; 95% CI: 2.91 to 18.46). Education, age, household income, noninjection drug use, and exposure to HIV prevention professionals were not significantly associated with PrEP/PEP awareness.

DISCUSSION

We documented a low prevalence of PrEP/PEP awareness. Less than 10% of the 3-year sample on Long Island and 15% of the NYC sample had previously heard of PrEP/PEP. When comparing awareness between risk groups, we found that IDU and HET had less awareness compared with MSM, despite MSM being sampled earlier, and although the MSM population was the only population sampled before the Food and Drug Administration announced the approval of PrEP.

The higher awareness among MSM is an important result pointing toward possible avenues for more efficient transmission of awareness of new treatment regimens. We note that the MSM sample was taken a year before the Food and Drug Administration approval of PrEP indicating vastly more efficient transmission among MSM. Moreover, the documented publicity for PrEP with MSM cannot fully explain this discrepancy, most publicity occurred after the first trial. Because recent research has established the importance of social networks on the transmission of information about HIV among MSM, this result points forcefully to the contribution of network connectivity.32 This does not mean that other groups are not networked, but it does suggest that MSM networks were discussing PrEP when IDU and HET networks were not.

On Long Island, a significant racial pattern was demonstrated, further supporting network theory. Black MSM had over 4 times increased odds of awareness of PrEP/PEP. Previous research has shown Black MSM to be “very inter-connected.”33 In NYC, HET, and IDU aged 18–29 had significant decreased odds of awareness, whereas MSM aged 18–29 had significant increased odds of awareness. Again, these findings suggest that PrEP/PEP awareness could potentially be spreading through networks. Examining younger MSM networks in NYC and Black MSM networks on Long Island, may aid public health officials in understanding how to increase awareness of important prevention drugs such as PrEP/PEP.

For both Long Island and NYC, a positive HIV test result was correlated with increased odds of PrEP/PEP awareness. Yet, only in NYC did we find exposure to HIV prevention professionals to be associated with increased odds of awareness. This is an important finding, indicating that health professions may need further education and training about PrEP/PEP on Long Island, as they need to be well versed and culturally competent to meet the needs of the communities they serve. In terms of noninjection drug use, which has been linked to increased HIV risk behavior, we find that in NYC participants who reported noninjection cocaine use had increased PrEP/PEP awareness. This supports previous studies and suggests that people who are already linked to care, or have higher risk behaviors, have greater awareness of PrEP/PEP. Last, neither education nor household income was significantly associated with PrEP/PEP awareness in the final models for both regions.

It is concerning that groups at-risk for HIV had little awareness of PrEP/PEP in both NYC and Long Island. Perhaps even more concerning is the inequality in awareness among groups at-risk for HIV. IDU and HET had less awareness than MSM, indicating that these groups may have less access to key prevention drugs, since they were not aware that PrEP or PEP existed and were therefore incapable of inquiring about it.

This study has several limitations. First, participants were recruited in NYC and Long Island, NY and therefore cannot represent the entire nation. Second, this is a cross-sectional study so causality cannot be inferred. Third, differences in methods for the populations may imply some problems with comparability. However, research has shown that both methods (venue-based time-space sampling and RDS) can yield similar demographic samples.34,35 Fourth, there is no way to disaggregate awareness of PrEP from PEP because of the wording of the survey question. Given that the variable measures both PrEP and PEP, we could assume that awareness about PrEP was lower than what was reported for PrEP/PEP combined as previous studies have shown. Fifth, survey data were self-reported, which may have associated biases. Sixth, a limitation for Long Island was a small sample of HIV-positive test results and Black MSM. Last, the differences of years in data collection could introduce bias into the analysis, as PrEP education has been increasing over time. However, the at-risk group sampled first (MSM in 2011) was the group with greater PrEP/PEP awareness.

Despite these limitations, this analysis is not without strengths. First, to our knowledge, this is the first comparison of these at-risk groups about PrEP/PEP awareness. The findings of this study highlight inequalities among groups in terms of awareness, which can greatly impact access. Second, the comparison between NYC and Long Island allows for a deeper understanding of differences regionally and identifies areas where populations differ and targeting messages can be made. Third, the focus on awareness at the insemination of a prevention tool allows for understanding how awareness spreads, which can be used for health initiatives broadly.

CONCLUSIONS

The findings of this analysis demonstrate that significant proportions of groups at-risk for HIV sampled in 2011 through 2013 were unaware of PrEP/PEP. When comparing awareness among risk groups, MSM had increased odds of PrEP/PEP awareness in both NYC and Long Island, and Black MSM having greater awareness on Long Island. Further MSM aged 18–29 years had greater awareness in NYC. These findings point to the possibility of networks being key to awareness dissemination. PrEP has been identified as a key tool in preventing new HIV infections, however, the first step to accessing prevention is to be aware that it exists.

A key tactic that can be harnessed and used with all risk populations is engaging community members (ie, using social networks) in prevention efforts, including the dissemination of awareness about PrEP and PEP. Public health officials should partner with community groups, providers, and testing centers for greater prevention successes. In addition, outreach and training targeting at-risk groups and the providers who serve them should include information about PrEP/PEP for all at-risk populations.

ACKNOWLEDGMENTS

The authors would like to thank Michael Schwartz, Kathleen Fallon, Michael Kimmel, Henry Fisher Raymond, Arnout Van de Rijt, and Sam Friedman for their feedback on this analysis.

REFERENCES

1. Grant RM, Lama JR, Anderson PL, et al. Preexposure chemoprophylaxis for HIV prevention in men who have sex with men. N Engl J Med. 2010;363:2587–2599.
2. Thigpen MC, Kebaabetswe PM, Paxton LA, et al. Antiretroviral preexposure prophylaxis for heterosexual HIV transmission in Botswana. N Engl J Med. 2012;367:423–434.
3. Choopanya K, Martin M, Suntharasamai P, et al. Antiretroviral prophylaxis for HIV infection in injecting drug users in Bangkok, Thailand (the Bangkok Tenofovir Study): a randomised, double-blind, placebo-controlled phase 3 trial. Lancet. 2013;381:2083–2090.
4. Baeten JM, Donnell D, Ndase P, et al. Antiretroviral prophylaxis for HIV prevention in heterosexual men and women. N Engl J Med. 2012;367:399–410.
5. Centers for Disease Control and Prevention. HIV Surveillance Report. 2015; Vol. 27. Available at: http://www.cdc.gov/hiv/library/reports/hiv-surveillance.html. Published November 2016. Accessed February 17, 2017.
6. Smith DK, Grohskopf LA, Black RJ, et al. Antiretroviral postexposure prophylaxis after sexual, injection-drug use, or other nonoccupational exposure to HIV in the United States: recommendations from the U.S. Department of Health and Human Services. MMWR Recomm Rep. 2005;54:1–20.
7. Smith D, Grant R, Weidle P, et al. Interim guidance: preexposure prophylaxis for the prevention of HIV infection in men who have sex with men. MMWR Morb Mortal Wkly Rep. 2011;60:65–68.
8. US Food and Drug Administration. FDA Approves First Drug for Reducing the Risk of Sexually Acquired HIV Infection. Silver Spring, MD: U.S. Food and Drug Administration; 2012.
9. Smith DK, Thigpen MC, Nesheim SR, et al. Interim guidance for clinicians considering the use of preexposure prophylaxis for the prevention of HIV infection in heterosexually active adults. MMWR Morb Mortal Wkly Rep. 2012;61:586–589.
10. Centers for Disease Control and Prevention (CDC). Update to interim guidance for Preexposure Prophylaxis (PrEP) for the prevention of HIV infection: PrEP for injecting drug users. MMWR Morb Mortal Wkly Rep. 2013;62:463–465.
11. New York State Department of Health AIDS Institute. New York State HIV/AIDS Epidemiologic Profile 2012. Available at: http://www.health.ny.gov/diseases/aids/general/statistics/epi/docs/2012_epidemiologic_profile.pdf. Accessed May 25, 2016.
12. Centers for Disease Control and Prevention. Statistics Overview. Available at: http://www.cdc.gov/hiv/statistics/overview/. Accessed February 8, 2016.
13. New York State. Governor Cuomo Announces Plan to End the AIDS Epidemic in New York State. Available at: http://www.governor.ny.gov/news/governor-cuomo-announces-plan-end-aids-epidemic-new-york-state. Accessed January 15, 2015.
14. White House Office of National AIDS Policy. National HIV/AIDS Strategy for the United States Updated to 2020. Washington, DC: National AIDS Policy; 2015.
15. Young I, McDaid L. How acceptable are antiretrovirals for the prevention of sexually transmitted HIV?: a review of research on the acceptability of oral pre-exposure prophylaxis and treatment as prevention. AIDS Behav. 2014;18:195–216.
16. Al-Tayyib AA, Thrun MW, Haukoos JS, et al. Knowledge of Pre-exposure Prophylaxis (PrEP) for HIV prevention among men who have sex with men in Denver, Colorado. AIDS Behav. 2014;18:340–347.
17. Leonardi M, Lee E, Tan DH. Awareness of, usage of and willingness to use HIV pre-exposure prophylaxis among men in downtown Toronto, Canada. Int J STD AIDS. 2011;22:738–741.
18. Liu AY, Kittredge PV, Vittinghoff E, et al. Limited knowledge and use of HIV post-and pre-exposure prophylaxis among gay and bisexual men. J Acquir Immune Defic Syndr. 2008;47:241–247.
19. Mantell JE, Sandfort TG, Hoffman S, et al. Knowledge and attitudes about Pre-exposure Prophylaxis (PrEP) among sexually active men who have sex with men (MSM) participating in New York city gay pride events. LGBT Health. 2014;1:93–97.
20. Dolezal C, Frasca T, Giguere R, et al. Awareness of post-exposure prophylaxis (PEP) and Pre-exposure Prophylaxis (PrEP) is low but interest is high among men engaging in condomless anal sex with men in Boston, Pittsburgh, and San Juan. AIDS Educ Prev. 2015;27:289–297.
21. Krakower DS, Mimiaga MJ, Rosenberger JG, et al. Limited awareness and low immediate uptake of pre-exposure prophylaxis among men who have sex with men using an internet social networking site. PLoS One. 2012;7:e33119.
22. Fallon S. Awareness and Acceptability of Pre-exposure Prophylaxis Among Men Who Have Sex With Men In Baltimore. Baltimore, Maryland: Johns Hopkins University; 2015.
23. Auerbach JD, Kinsky S, Brown G, et al. Knowledge, attitudes, and likelihood of Pre-exposure Prophylaxis (PrEP) use among US women at risk of acquiring HIV. AIDS Patient Care STDS. 2015;29:102–110.
24. Stein M, Thurmond P, Bailey G. Willingness to use HIV pre-exposure prophylaxis among opiate users. AIDS Behav. 2014;18:1694–1700.
25. Escudero DJ, Kerr T, Wood E, et al. Acceptability of HIV pre-exposure prophylaxis (PrEP) among people who inject drugs (PWID) in a Canadian setting. AIDS Behav. 2015;19:752–757.
26. Voetsch AC, Heffelfinger JD, Begley EB, et al. Knowledge and use of preexposure and postexposure prophylaxis among attendees of Minority Gay Pride events, 2005 through 2006. J Acquir Immune Defic Syndr. 2007;46:378–380.
27. Mehta SA, Silvera R, Bernstein K, et al. Awareness of post-exposure HIV prophylaxis in high-risk men who have sex with men in New York City. Sex Transm Infect. 2011;87:344–348.
28. MacKellar DA, Gallagher KM, Finlayson T, et al. Surveillance of HIV risk and prevention behaviors of men who have sex with men: a national application of venue-based, time-space sampling. Public Health Rep. 2007;122(suppl 1):39–47.
29. Heckathorn DD. Respondent-Driven Sampling: A New Approach to the Study of Hidden Populations. New York, NY: Social Problems; 1997;44:174–199.
30. Du Bois WEB, Eaton I. The Philadelphia Negro: A Social Study. Philadelphia, PA: University of Pennsylvania Press; 1899.
31. Allison PD. Logistic Regression Using SAS: Theory and Application. Cary, NC: SAS Institute; 2012.
32. Amirkhanian YA. Social networks, sexual networks and HIV risk in men who have sex with men. Curr HIV/AIDS Rep. 2014;11:81–92.
33. Fuqua V, Chen Y, Packer T, et al. Using social networks to reach Black MSM for HIV testing and linkage to care. AIDS Behav. 2012;16:256–265.
34. Kendall C, Kerr LR, Gondim RC, et al. An empirical comparison of respondent-driven sampling, time location sampling, and snowball sampling for behavioral surveillance in men who have sex with men, Fortaleza, Brazil. AIDS Behav. 2008;12:97–104.
35. Tran HV, Le LN, Johnston LG, et al. Sampling males who inject drugs in Haiphong, Vietnam: comparison of time-location and respondent-driven sampling methods. J Urban Health. 2015;92:744–757.
Keywords:

preexposure prophylaxis; postexposure prophylaxis; HIV; men who have sex with men; people who inject drugs; high-risk heterosexuals

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