Table 1.

Text message content examples from the uTECH intervention using the Information-Motivation-Behavior Skills (IMB) model.

	PrEPa initiation	PrEP adherence	Sexual risk reduction	Substance use harm reduction
Information	“PrEP reduces the risk of getting HIV from sex by approximately 99%—if taken on an ongoing basis before sex and continued after sex. It is also called Truvada or Descovy.”	“Did you know? The Food and Drug Administration approved injectable PrEP, which is an option for people who are tired of taking a pill every day. It is an injection given every 2 months. Find out more at: https://www.fda.gov/news-events/press-announcements/fda-approves-first-injectable-treatment-hiv-pre-exposure-prevention.”	“If you had unprotected sex, you can take PEP (postexposure prophylaxis) up to 72 hours after possible exposure to prevent HIV. Watch a video to learn more: https://www.youtube.com/​watch?v=Yu82TFo6j94&featu”	“Here is a tip for staying hydrated while drinking: drink 1 glass of water for every alcoholic beverage you have. This is known as the 1-for-1 rule and may help moderate your drinking and lessen the chance of a hangover.”
Motivation	“Did you know that studies show taking PrEP lowers HIV-related anxiety? Are you less anxious about HIV when you are on PrEP?”	“Did you know that studies show taking PrEP lowers HIV-related anxiety? Are you less anxious about getting HIV when you are on PrEP?”	“Nervous about getting STIb testing? It is safer to get tested and know the results. Here is how others overcame their concerns about STI testing: https://www.youtube.com/​watch?v=rN5d_XQKRxg.”	“If you ever inject with a friend, you could consider doing so at a SISc. SIS refers to places where people who use injectable, but illegal, opioids such as heroin can do so without fear of overdose, prosecution, or spreading disease. You can try looking up sites in your area to find them or contact a member of the research team for assistance.”
Behavior	“Reply with the number of the statement that applies to you: 1. I have talked to a medical provider about getting PrEP but have not yet started taking it. 2. I have already talked to a medical provider about getting PrEP and have begun taking it. 3. I have not talked to a medical provider about getting PrEP and have not taken it yet.”	“Reply with the number of the statement that applies to you: Have you at any point considered stopping PrEP? 1. No, I am happy with PrEP and expect to continue taking it. 2. No, I am neither happy nor unhappy with PrEP, it just does not seem like an option to stop PrEP use. 3. Yes, but I changed my mind and expect to continue taking it. 4. Yes, and I did stop use for a period of time. Since then, I have resumed and plan to continue taking it. 5. Yes, and I am planning on discontinuing use soon.”	“Reply with the number of the statement that applies to you: 1. In the past month, I have gotten tested for HIV or ≥1 STIs. 2. In the past month, I have not gotten tested, but I have booked an appointment or set a date to get tested in the near future. 3. In the past month, I have not gotten tested and currently do not have an appointment or plan to do so.”	“Reply with the number of the statement that applies to you: Have you ever trusted someone to supervise you (or trip-sit) as you inject for safety purposes? 1. Yes, always. 2. Yes, but only once or a few times. 3. Yes, but I would not do it again. 4. No, but I would like to in the future. 5. No, I do not feel comfortable being supervised.”

^aPrEP: pre-exposure prophylaxis.

^bSTI: sexually transmitted infection.

^cSIS: safe injection site.