Men who have sex with men (MSM), especially young men who have sex with men (YMSM), and transgender women (TGW) have some of the highest rates of HIV and syphilis diagnoses in the United States. The goal of this study is to pilot the mobile Lab (mLab) App Plus to assess YMSM's and YTGW's abilities to perform and interpret self-tests for HIV and syphilis and consequently increase the number of YMSM and young transgender woman (YTGW) who initiate self-testing for HIV and syphilis.

From 2018 to 2019, the rate of syphilis increased by 11.2%. It has increased steadily since 2000 especially among men, in which MSM bear a disproportionate majority of cases (47% of all cases were among MSM in 2019). HIV and syphilis rates continue to rise among YMSM. While MSM account for only about 2% of the US population, they are most affected by HIV, constituting 56% of people living with HIV (PLWH).

Moreover, the rate of syphilis among MSM is profoundly elevated, at least 100 times higher than that in men who have sex with women and even higher among YMSM. Importantly, syphilis makes it easier to both acquire and transmit HIV, and about half of MSM who have syphilis are co-infected with HIV. The risk of syphilis and HIV continues to rise in YMSM in New York City, the study site. Given these epidemiologic risk factors for HIV and syphilis, there is a strong scientific premise for this pilot study that proposes to test innovative and effective HIV and sexually transmitted infection (STI) testing, prevention, and treatment models. Given that approximately 17% of MSM living with HIV in the U.S. are unaware of their status and significant comorbid syphilis in that population, both pathogens may be simultaneously transmitted. The increasing number of syphilis diagnosed in MSM highlights the importance of STI control in this population, not just for the health of the patient, but also for prevention of HIV and syphilis in uninfected persons. YMSM and YTGW, and specifically Blacks and Latinos, are disproportionately infected with HIV.

In response to the need for interventions to increase HIV testing in youth, our study team developed the mLab App, which affords advantages over existing self-test options to support the potential for higher uptake of the HIV self-test. The app provides HIV prevention information, push notification reminders for testing, step-by-step instructions for using the OraQuick HIV tests (OraQuick), and an image upload function so individuals can send an image of their OraQuick HIV test to the study team. In response to the mLab App study and the scientific evidence of need for at-home syphilis point of care (POC) testing among YMSM and YTGW, we propose to implement the mLab App Plus to assess YMSM's and YTGW's abilities to perform and interpret self-tests for HIV and syphilis and consequently increase the number of YMSM and YTGW who initiate self-testing for HIV and syphilis.

Inclusion Criteria:

• 18-39 years of age
• Assigned male sex at birth and identify as (1) a man or (2) a trans woman
• Understand and read English
• Self-identify as any race or ethnicity
• Substantial risk for acquiring HIV infection per CDC (Centers for Disease Control) guidance
• All participants must report having sex with a man/men
• Smart phone ownership
• Self-report being HIV-negative or unknown status
• Self-report being negative for syphilis or unknown status
• Not having been tested for HIV or syphilis in the past 3 months
• Understand the limitations of the duplex lateral flow test and the mLab App Plus (e.g., a confirmatory test is needed and self-test must be performed in the presence of a qualified clinician)

Assigned male sex at birth and identify as (1) a man or (2) a trans woman

3 months

Participants will be randomly assigned to one of two trial arms using the randomization module in REDCap. We will use block randomization with randomly permutated blocks to reduce opportunities for selection bias