Callisto Boka
Current Organizations / Institutes
The organizations/institutes from the scholar's latest article
Research Subjects
Callisto Boka has a total of 27 co-authors. Here are the top co-authors by number of shared publications:
- Chenglin Hong
University of Connecticut, Hartford, USA
4 shared publications - Elizabeth Sc Wu
School of Nursing, University of California Los Angeles, Los Angeles, CA, USA
4 shared publications - Ian Walter Holloway
Joe C. Wen School of Nursing, University of California Los Angeles
4 shared publications - Mehrab Beikzadeh
Department of Computer Science, Henry Samueli School of Engineering, University of California, Los Angeles, Los Angeles, California, USA
4 shared publications - Alexandra Avendaño
Department of Social Welfare, University of California, Los Angeles, Los Angeles, CA, United States
3 shared publications - Kimmo Kärkkäinen
University of California Los Angeles
3 shared publications
Latest Publications
- Open Access
- 10 January 2026
- Published by Springer Nature in Prevention Science
- Vol. 27 (7) , 1-16
Utilizing Machine Learning for Predicting PrEP Use Status Among Sexual and Gender Minority Young Adults
Pre-exposure prophylaxis (PrEP) is a highly effective biomedical prevention tool for HIV yet remains underutilized among key populations, particularly among young sexual and gender minorities (SGM). Recognizing the popularity of specific dating and social media apps among SGM young adults, we leveraged user data from these platforms to build a machine learning (ML) model that could inform targeted, data-driven interventions aimed at improving PrEP uptake and adherence. We adapted eWellness, an Android mobile app, to passively collect data from research participants capturing mobile app usage, keystroke patterns and logs, and GPS location data between 2021 and 2024. These data were used to train a ML model to predict self-reported PrEP use. Model accuracy was evaluated through F1 scores across different data types and feature combinations. Study protocols were developed in collaboration with community partners and adhered to strict ethical and privacy standards. A total of 82 SGM young adults participated, with 46 (56%) reporting PrEP use at baseline. Our machine learning model demonstrated good predictive accuracy for predicting PrEP use and non-use, achieving an F1 score of 0.84 (PrEP use) and 0.82 (non-use) outcomes when incorporating data from all mobile apps, including messaging, dating, and social media mobile apps. By contrast, predictions based solely on social media mobile app usage, language associated with sexual behavior and substance use risk, or location monitoring demonstrated worse accuracy (F1 scores of 0.79/0.75, 0.70/0.57, and 0.70/0.52, respectively). Additional feature extraction methods, as well as various combinations of these features, were also tested. However, none achieved predictive accuracy as well as the model incorporating all mobile app usage data combined. This study demonstrates the potential of machine learning to accurately predict PrEP use status among SGM young adults. The findings offer a foundation for developing more personalized PrEP promotion strategies, particularly among SGM young adults who use social media and dating apps. Future research should assess the model’s adaptability across diverse SGM subgroups to further inform intervention development. Registry: ClinicalTrials.gov, ID: NCT04710901, November 9, 2020.
- 10 January 2026
- Published by Springer Nature in Prevention Science
- Vol. 27 (7) , 1-16
Open AccessUtilizing Machine Learning for Predicting PrEP Use Status Among Sexual and Gender Minority Young Adults
Pre-exposure prophylaxis (PrEP) is a highly effective biomedical prevention tool for HIV yet remains underutilized among key populations, particularly among young sexual and gender minorities (SGM). Recognizing the popularity of specific dating and social media apps among SGM young adults, we leveraged user data from these platforms to build a machine learning (ML) model that could inform targeted, data-driven interventions aimed at improving PrEP uptake and adherence. We adapted eWellness, an Android mobile app, to passively collect data from research participants capturing mobile app usage, keystroke patterns and logs, and GPS location data between 2021 and 2024. These data were used to train a ML model to predict self-reported PrEP use. Model accuracy was evaluated through F1 scores across different data types and feature combinations. Study protocols were developed in collaboration with community partners and adhered to strict ethical and privacy standards. A total of 82 SGM young adults participated, with 46 (56%) reporting PrEP use at baseline. Our machine learning model demonstrated good predictive accuracy for predicting PrEP use and non-use, achieving an F1 score of 0.84 (PrEP use) and 0.82 (non-use) outcomes when incorporating data from all mobile apps, including messaging, dating, and social media mobile apps. By contrast, predictions based solely on social media mobile app usage, language associated with sexual behavior and substance use risk, or location monitoring demonstrated worse accuracy (F1 scores of 0.79/0.75, 0.70/0.57, and 0.70/0.52, respectively). Additional feature extraction methods, as well as various combinations of these features, were also tested. However, none achieved predictive accuracy as well as the model incorporating all mobile app usage data combined. This study demonstrates the potential of machine learning to accurately predict PrEP use status among SGM young adults. The findings offer a foundation for developing more personalized PrEP promotion strategies, particularly among SGM young adults who use social media and dating apps. Future research should assess the model’s adaptability across diverse SGM subgroups to further inform intervention development. Registry: ClinicalTrials.gov, ID: NCT04710901, November 9, 2020.
- Open Access
- 12 August 2025
- Published by JMIR Publications Inc. in Online Journal of Public Health Informatics
- Vol. 17, e68013
Identifying Substance Use and High-Risk Sexual Behavior Among Sexual and Gender Minority Youth by Using Mobile Phone Data: Development and Validation Study
Background: Sexual and gender minority (SGM) individuals are at heightened risk for substance use and sexually transmitted infections than their non-SGM peers. Collecting mobile phone usage data passively may open new opportunities for personalizing interventions, as behavioral risks could be identified without user input. Objective: This study aimed to determine (1) whether passively sensed mobile phone data can be used to identify substance use and sexual risk behaviors for sexually transmitted infection (STI) and HIV transmission among young SGM who have sex with men, (2) which outcomes can be predicted with a high level of accuracy, and (3) which passive data sources are most predictive of these outcomes. Methods: We developed a mobile phone app to collect participants’ messaging, location, and app use data and trained a machine learning model to predict risk behaviors for STI and HIV transmission. We used Scikit-learn to train logistic regression and gradient boosting classification models with simple linear model specification to predict participants' substance use and sexual behaviors (ie, condomless anal sex, number of sexual partners, and methamphetamine use), which were validated using self-report questionnaires. F1-scores were used to quantify prediction accuracy of the model using different data sources (and combinations of these sources) for prediction. Differences between text, location, app use, and Linguistic Inquiry and Word Count (LIWC) domains by outcome were investigated using independent t tests where associations were considered significant at P<.05. Results: Among participants (n=82) who identified as SGM, were sexually active, and reported recent substance use, our model was highly predictive of methamphetamine use and having ≥6 sexual partners (F1-scores as high as 0.83 and 0.69, respectively). The model was less predictive of condomless anal sex (highest F1-score 0.38). Overall, text-based features were found to be most predictive, but app use and location data improved predictive accuracy, particularly for detecting ≥6 sexual partners. Methamphetamine use was significantly associated with dating app use (P=.01) and use of sex-related words (P=.002). Having ≥6 sex partners was associated with dating app use (0.02), use of sex-related words (P=.001), and traveling a further distance from home (P=.03), on average, compared to participants with fewer sex partners. Methamphetamine users were more likely to use social (P=.002) and affect words (P=.003) and less likely to use drive-related words (P=.02). People having 6 or more partners were more likely to use social, affect words, and cognitive process-related words (P=.003 and .004 respectively). Conclusions: Our results show that passively collected mobile phone data may be useful in detecting sexual risk behaviors. Expanding data collection may improve the results further, as certain behaviors, such as injection drug use, were quite rare in the study sample. These models may be used to personalize STI and HIV prevention as well as substance use harm reduction interventions.
- 12 August 2025
- Published by JMIR Publications Inc. in Online Journal of Public Health Informatics
- Vol. 17, e68013
Open AccessIdentifying Substance Use and High-Risk Sexual Behavior Among Sexual and Gender Minority Youth by Using Mobile Phone Data: Development and Validation Study
Background: Sexual and gender minority (SGM) individuals are at heightened risk for substance use and sexually transmitted infections than their non-SGM peers. Collecting mobile phone usage data passively may open new opportunities for personalizing interventions, as behavioral risks could be identified without user input. Objective: This study aimed to determine (1) whether passively sensed mobile phone data can be used to identify substance use and sexual risk behaviors for sexually transmitted infection (STI) and HIV transmission among young SGM who have sex with men, (2) which outcomes can be predicted with a high level of accuracy, and (3) which passive data sources are most predictive of these outcomes. Methods: We developed a mobile phone app to collect participants’ messaging, location, and app use data and trained a machine learning model to predict risk behaviors for STI and HIV transmission. We used Scikit-learn to train logistic regression and gradient boosting classification models with simple linear model specification to predict participants' substance use and sexual behaviors (ie, condomless anal sex, number of sexual partners, and methamphetamine use), which were validated using self-report questionnaires. F1-scores were used to quantify prediction accuracy of the model using different data sources (and combinations of these sources) for prediction. Differences between text, location, app use, and Linguistic Inquiry and Word Count (LIWC) domains by outcome were investigated using independent t tests where associations were considered significant at P<.05. Results: Among participants (n=82) who identified as SGM, were sexually active, and reported recent substance use, our model was highly predictive of methamphetamine use and having ≥6 sexual partners (F1-scores as high as 0.83 and 0.69, respectively). The model was less predictive of condomless anal sex (highest F1-score 0.38). Overall, text-based features were found to be most predictive, but app use and location data improved predictive accuracy, particularly for detecting ≥6 sexual partners. Methamphetamine use was significantly associated with dating app use (P=.01) and use of sex-related words (P=.002). Having ≥6 sex partners was associated with dating app use (0.02), use of sex-related words (P=.001), and traveling a further distance from home (P=.03), on average, compared to participants with fewer sex partners. Methamphetamine users were more likely to use social (P=.002) and affect words (P=.003) and less likely to use drive-related words (P=.02). People having 6 or more partners were more likely to use social, affect words, and cognitive process-related words (P=.003 and .004 respectively). Conclusions: Our results show that passively collected mobile phone data may be useful in detecting sexual risk behaviors. Expanding data collection may improve the results further, as certain behaviors, such as injection drug use, were quite rare in the study sample. These models may be used to personalize STI and HIV prevention as well as substance use harm reduction interventions.
- Open Access
- 25 October 2024
- Published by JMIR Publications Inc. in JMIR Preprints
Identifying Substance Use and High-Risk Sexual Behavior Among Sexual and Gender Minority Young People Using Mobile Phone Data: Development and Validation Study (Preprint)
BACKGROUND Sexual and gender minority (SGM) individuals are at heightened risk for substance use and sexually transmitted infections than their non-SGM peers. Collecting mobile phone usage data passively may open new opportunities for personalizing interventions, as behavioral risks could be identified without user input. OBJECTIVE Our objective was to determine whether passively sensed mobile phone data can be used to identify substance use and sexual risk behaviors for STI and HIV transmission among young SGM who have sex with men. METHODS We developed a mobile phone app to collect participants’ messaging, location, and app use data. Based on community-engaged qualitative research, we trained a machine learning model to identify risk behaviors for STI and HIV transmission, such as condomless anal sex, number of sexual partners, and methamphetamine use. We validated these behaviors using self-report and evaluated their association with mobile phone use data. RESULTS We recruited 82 SGM young people who have sex to use our data collection app, and among those users, our model was highly predictive of methamphetamine use and having 6+ sexual partners (F1 scores 0.83 and 0.69 respectively). The model was less predictive of condomless anal sex (F1 score 0.38). Overall, text-based features were found to be most predictive, but app use and location data improved the results, particularly for detecting 6+ sexual partners. CONCLUSIONS Our results show that passively collected mobile phone data may be useful in detecting sexual risk behaviors. Expanding data collection may improve the results further, as certain behaviors, such as injection drug use, were quite rare in the study sample. These models may be used to personalize STI and HIV prevention as well as substance use harm reduction interventions. INTERNATIONAL REGISTERED REPORT RR2-10.2196/58448
- 25 October 2024
- Published by JMIR Publications Inc. in JMIR Preprints
Open AccessIdentifying Substance Use and High-Risk Sexual Behavior Among Sexual and Gender Minority Young People Using Mobile Phone Data: Development and Validation Study (Preprint)
BACKGROUND Sexual and gender minority (SGM) individuals are at heightened risk for substance use and sexually transmitted infections than their non-SGM peers. Collecting mobile phone usage data passively may open new opportunities for personalizing interventions, as behavioral risks could be identified without user input. OBJECTIVE Our objective was to determine whether passively sensed mobile phone data can be used to identify substance use and sexual risk behaviors for STI and HIV transmission among young SGM who have sex with men. METHODS We developed a mobile phone app to collect participants’ messaging, location, and app use data. Based on community-engaged qualitative research, we trained a machine learning model to identify risk behaviors for STI and HIV transmission, such as condomless anal sex, number of sexual partners, and methamphetamine use. We validated these behaviors using self-report and evaluated their association with mobile phone use data. RESULTS We recruited 82 SGM young people who have sex to use our data collection app, and among those users, our model was highly predictive of methamphetamine use and having 6+ sexual partners (F1 scores 0.83 and 0.69 respectively). The model was less predictive of condomless anal sex (F1 score 0.38). Overall, text-based features were found to be most predictive, but app use and location data improved the results, particularly for detecting 6+ sexual partners. CONCLUSIONS Our results show that passively collected mobile phone data may be useful in detecting sexual risk behaviors. Expanding data collection may improve the results further, as certain behaviors, such as injection drug use, were quite rare in the study sample. These models may be used to personalize STI and HIV prevention as well as substance use harm reduction interventions. INTERNATIONAL REGISTERED REPORT RR2-10.2196/58448
- Open Access
- 20 August 2024
- Published by JMIR Publications Inc. in JMIR Research Protocols
- Vol. 13 (1) , e58448
Novel Machine Learning HIV Intervention for Sexual and Gender Minority Young People Who Have Sex With Men (uTECH): Protocol for a Randomized Comparison Trial
Background: Sexual and gender minority (SGM) young people are disproportionately affected by HIV in the United States, and substance use is a major driver of new infections. People who use web-based venues to meet sex partners are more likely to report substance use, sexual risk behaviors, and sexually transmitted infections. To our knowledge, no machine learning (ML) interventions have been developed that use web-based and digital technologies to inform and personalize HIV and substance use prevention efforts for SGM young people. Objective: This study aims to test the acceptability, appropriateness, and feasibility of the uTECH intervention, a SMS text messaging intervention using an ML algorithm to promote HIV prevention and substance use harm reduction among SGM people aged 18 to 29 years who have sex with men. This intervention will be compared to the Young Men’s Health Project (YMHP) alone, an existing Centers for Disease Control and Prevention best evidence intervention for young SGM people, which consists of 4 motivational interviewing–based counseling sessions. The YMHP condition will receive YMHP sessions and will be compared to the uTECH+YMHP condition, which includes YMHP sessions as well as uTECH SMS text messages. Methods: In a study funded by the National Institutes of Health, we will recruit and enroll SGM participants (aged 18-29 years) in the United States (N=330) to participate in a 12-month, 2-arm randomized comparison trial. All participants will receive 4 counseling sessions conducted over Zoom (Zoom Video Communications, Inc) with a master’s-level social worker. Participants in the uTECH+YMHP condition will receive curated SMS text messages informed by an ML algorithm that seek to promote HIV and substance use risk reduction strategies as well as undergoing YMHP counseling. We hypothesize that the uTECH+YMHP intervention will be considered acceptable, appropriate, and feasible to most participants. We also hypothesize that participants in the combined condition will experience enhanced and more durable reductions in substance use and sexual risk behaviors compared to participants receiving YMHP alone. Appropriate statistical methods, models, and procedures will be selected to evaluate primary hypotheses and behavioral health outcomes in both intervention conditions using an α<.05 significance level, including comparison tests, tests of fixed effects, and growth curve modeling. Results: This study was funded in August 2019. As of June 2024, all participants have been enrolled. Data analysis has commenced, and expected results will be published in the fall of 2025. Conclusions: This study aims to develop and test the acceptability, appropriateness, and feasibility of uTECH, a novel approach to reduce HIV risk and substance use among SGM young adults. Trial Registration: ClinicalTrials.gov NCT04710901; https://clinicaltrials.gov/study/NCT04710901 International Registered Report Identifier (IRRID): DERR1-10.2196/58448
- 20 August 2024
- Published by JMIR Publications Inc. in JMIR Research Protocols
- Vol. 13 (1) , e58448
Open AccessNovel Machine Learning HIV Intervention for Sexual and Gender Minority Young People Who Have Sex With Men (uTECH): Protocol for a Randomized Comparison Trial
Background: Sexual and gender minority (SGM) young people are disproportionately affected by HIV in the United States, and substance use is a major driver of new infections. People who use web-based venues to meet sex partners are more likely to report substance use, sexual risk behaviors, and sexually transmitted infections. To our knowledge, no machine learning (ML) interventions have been developed that use web-based and digital technologies to inform and personalize HIV and substance use prevention efforts for SGM young people. Objective: This study aims to test the acceptability, appropriateness, and feasibility of the uTECH intervention, a SMS text messaging intervention using an ML algorithm to promote HIV prevention and substance use harm reduction among SGM people aged 18 to 29 years who have sex with men. This intervention will be compared to the Young Men’s Health Project (YMHP) alone, an existing Centers for Disease Control and Prevention best evidence intervention for young SGM people, which consists of 4 motivational interviewing–based counseling sessions. The YMHP condition will receive YMHP sessions and will be compared to the uTECH+YMHP condition, which includes YMHP sessions as well as uTECH SMS text messages. Methods: In a study funded by the National Institutes of Health, we will recruit and enroll SGM participants (aged 18-29 years) in the United States (N=330) to participate in a 12-month, 2-arm randomized comparison trial. All participants will receive 4 counseling sessions conducted over Zoom (Zoom Video Communications, Inc) with a master’s-level social worker. Participants in the uTECH+YMHP condition will receive curated SMS text messages informed by an ML algorithm that seek to promote HIV and substance use risk reduction strategies as well as undergoing YMHP counseling. We hypothesize that the uTECH+YMHP intervention will be considered acceptable, appropriate, and feasible to most participants. We also hypothesize that participants in the combined condition will experience enhanced and more durable reductions in substance use and sexual risk behaviors compared to participants receiving YMHP alone. Appropriate statistical methods, models, and procedures will be selected to evaluate primary hypotheses and behavioral health outcomes in both intervention conditions using an α<.05 significance level, including comparison tests, tests of fixed effects, and growth curve modeling. Results: This study was funded in August 2019. As of June 2024, all participants have been enrolled. Data analysis has commenced, and expected results will be published in the fall of 2025. Conclusions: This study aims to develop and test the acceptability, appropriateness, and feasibility of uTECH, a novel approach to reduce HIV risk and substance use among SGM young adults. Trial Registration: ClinicalTrials.gov NCT04710901; https://clinicaltrials.gov/study/NCT04710901 International Registered Report Identifier (IRRID): DERR1-10.2196/58448
- Open Access
- 15 March 2024
- Published by JMIR Publications Inc. in JMIR Preprints
Novel Machine Learning HIV Intervention for Sexual and Gender Minority Young People Who Have Sex With Men (uTECH): Protocol for a Randomized Comparison Trial (Preprint)
Journal of Medical Internet Research - International Scientific Journal for Medical Research, Information and Communication on the Internet #Preprint #PeerReviewMe: Warning: This is a unreviewed preprint. Readers are warned that the document has not been peer-reviewed by expert/patient reviewers or an academic editor, may contain misleading claims, and is likely to undergo changes before final publication, if accepted, or may have been rejected/withdrawn. Readers with interest and expertise are encouraged to sign up as peer-reviewer, if the paper is within an open peer-review period. Please cite this preprint only for review purposes or for grant applications and CVs (if you are the author). Background: Sexual and gender minority (SGM) young people are disproportionately affected by HIV in the United States, and substance use is a major driver of new infections. People who use online venues to meet sexual partners are more likely to report substance use, sexual risk behaviors, and sexually transmitted infections (STIs). To our knowledge, no machine learning interventions have been developed that utilize online and digital technologies to inform and personalize HIV and substance use prevention efforts with sexual and gender minorities. Objective: This study is a two-arm randomized comparison trial that tests the acceptability, appropriateness, and feasibility of the uTECH intervention, a text message intervention using a machine learning algorithm to promote substance use harm reduction and safer behaviors among 18-29 year old sexual and gender minority people who have sex with men. This intervention will be compared to YMHP (Young Men’s Health Program) alone, an existing CDC Best Evidence intervention for young SGM men, that consists of 4 motivational interviewing-based counseling sessions. The YMHP condition will receive YMHP sessions and will be compared to the uTECH+YMHP condition, which includes YMHP sessions as well as uTECH text messages. Methods: In a study funded by the National Institutes of Health, we will recruit and enroll sexual and gender minority participants (aged 18 to 29) in the United States (N=330) to participate in a 12-month study. All participants will receive 4 counseling sessions conducted over Zoom with a Masters-level social worker. Participants in the uTECH+YMHP condition will receive curated text messages informed by a machine learning algorithm that seeks to promote HIV and substance use risk reduction strategies as well as undergoing YMHP counseling. Over the course of the study, participants will receive between $350 to $450 in incentives, depending on condition assignment. We hypothesize the uTECH+YMHP intervention will be considered acceptable, appropriate, and feasible to most participants. We also hypothesize that participants in the combined condition will experience enhanced and more durable reductions in substance use and sexual risk behaviors compared to participants receiving YMHP alone. Results: This study will test the acceptability, appropriateness, and feasibility of uTECH for sexual and gender minority young adults in the United States (N=330). uTECH seeks to reduce HIV transmission by sending personalized and curated messages promoting harm reduction and safer sex behaviors based on a machine learning algorithm. Conclusions: This study aims develop and test the acceptability, appropriateness, and feasibility of uTECH, a novel approach to reduce HIV risk and substance use among sexual and gender minority young adults. Clinical Trial: Clinical Trials ID: NCT04710901
- 15 March 2024
- Published by JMIR Publications Inc. in JMIR Preprints
Open AccessNovel Machine Learning HIV Intervention for Sexual and Gender Minority Young People Who Have Sex With Men (uTECH): Protocol for a Randomized Comparison Trial (Preprint)
Journal of Medical Internet Research - International Scientific Journal for Medical Research, Information and Communication on the Internet #Preprint #PeerReviewMe: Warning: This is a unreviewed preprint. Readers are warned that the document has not been peer-reviewed by expert/patient reviewers or an academic editor, may contain misleading claims, and is likely to undergo changes before final publication, if accepted, or may have been rejected/withdrawn. Readers with interest and expertise are encouraged to sign up as peer-reviewer, if the paper is within an open peer-review period. Please cite this preprint only for review purposes or for grant applications and CVs (if you are the author). Background: Sexual and gender minority (SGM) young people are disproportionately affected by HIV in the United States, and substance use is a major driver of new infections. People who use online venues to meet sexual partners are more likely to report substance use, sexual risk behaviors, and sexually transmitted infections (STIs). To our knowledge, no machine learning interventions have been developed that utilize online and digital technologies to inform and personalize HIV and substance use prevention efforts with sexual and gender minorities. Objective: This study is a two-arm randomized comparison trial that tests the acceptability, appropriateness, and feasibility of the uTECH intervention, a text message intervention using a machine learning algorithm to promote substance use harm reduction and safer behaviors among 18-29 year old sexual and gender minority people who have sex with men. This intervention will be compared to YMHP (Young Men’s Health Program) alone, an existing CDC Best Evidence intervention for young SGM men, that consists of 4 motivational interviewing-based counseling sessions. The YMHP condition will receive YMHP sessions and will be compared to the uTECH+YMHP condition, which includes YMHP sessions as well as uTECH text messages. Methods: In a study funded by the National Institutes of Health, we will recruit and enroll sexual and gender minority participants (aged 18 to 29) in the United States (N=330) to participate in a 12-month study. All participants will receive 4 counseling sessions conducted over Zoom with a Masters-level social worker. Participants in the uTECH+YMHP condition will receive curated text messages informed by a machine learning algorithm that seeks to promote HIV and substance use risk reduction strategies as well as undergoing YMHP counseling. Over the course of the study, participants will receive between $350 to $450 in incentives, depending on condition assignment. We hypothesize the uTECH+YMHP intervention will be considered acceptable, appropriate, and feasible to most participants. We also hypothesize that participants in the combined condition will experience enhanced and more durable reductions in substance use and sexual risk behaviors compared to participants receiving YMHP alone. Results: This study will test the acceptability, appropriateness, and feasibility of uTECH for sexual and gender minority young adults in the United States (N=330). uTECH seeks to reduce HIV transmission by sending personalized and curated messages promoting harm reduction and safer sex behaviors based on a machine learning algorithm. Conclusions: This study aims develop and test the acceptability, appropriateness, and feasibility of uTECH, a novel approach to reduce HIV risk and substance use among sexual and gender minority young adults. Clinical Trial: Clinical Trials ID: NCT04710901