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Principal Investigator: CONNIE L CELUM
Organization: UNIVERSITY OF CALIFORNIA, SAN FRANCISCO
Fiscal Year: 2024
Award: $1,628,180
Funding agency: National Institute of Allergy and Infectious Diseases
Sexually transmitted infections (STIs) continue to rise in the US and globally, disproportionately affecting men
who have sex with men (MSM) and transgender women (TW), with the highest rates in people of color, living
with HIV (PLWH) and those ≤30 years of age. Doxycycline taken within 72 hours after condomless sex as post-
exposure prophylaxis (doxy-PEP) is highly effective and significantly reduces incident STIs in MSM/TW who are
at elevated risk of recurrent STIs. Randomized trials demonstrated doxy-PEP reduced chlamydia (CT) and
syphilis by >80% and gonorrhea (GC) by >50%, was safe, well-tolerated, and highly acceptable. Doxy-PEP is
an important public health tool with potential to help turn the tide on the US's persistent STI epidemic. In October
2023, the CDC gave a Grade A1 recommendation for doxy-PEP for MSM/TW with recent STIs. However, to be
effective, doxy-PEP uptake, adherence, and persistence need to be high among MSM/TW at elevated risk for
recurrent STIs which includes MSM/TW who already experience significant health disparities, based on age
(under age 30) race/ethnicity (Black and Latinx), living with HIV or are taking HIV PrEP. The roll-out of HIV PrEP
in the US is an important reminder of the necessity to ensure equitable access to populations with highest need.
In parallel with enthusiasm for the public health potential of doxy-PEP, important concerns remain about longer-
term doxy-PEP use and potential antimicrobial resistance (AMR) in GC and clinically important “bystander”
bacteria, such as Staph aureus and Strep pneumoniae. To address these questions, we propose an open cohort
of MSM and TW currently taking doxy-PEP or initiating doxy-PEP per local or national guidelines in sexual health
and HIV clinics in five geographically and demographically diverse cities (Atlanta, Detroit, Miami, San Francisco
and Seattle). Our Specific Aims are to: 1) Evaluate guideline-based doxy-PEP effectiveness and patterns
of use in 2500 MSM and TG by key characteristics, including race/ethnicity, age, gender identity and HIV
serostatus as follows: SubAim 1a: Compare doxy-PEP effectiveness and patterns of use in doxy-PEP
users to a threshold consistent with at least 50% reduction in early syphilis, chlamydia and gonorrhea
from the DoxyPEP Study. SubAim 1b: Use mixed methods, including qualitative methods, to understand
users' decision-making about doxy-PEP use with different partners and continuation of doxy-PEP over
time. SubAim 1c: Establish a doxy-PEP to need ratio to assess gaps in doxy-PEP uptake and use, and
to guide efforts to increase equitable access. 2) Assess the impact of doxy-PEP on antimicrobial
resistance in gonorrhea and clinically relevant bystander bacteria.
Terms: <AIDS Virus><Acquired Immune Deficiency Syndrome Virus><Acquired Immunodeficiency Syndrome Virus><Active Follow-up><Address><Adherence><Affect><Age><Age Years><Antibiotic Agents><Antibiotic Drugs><Antibiotics><Antimicrobial Resistance><Bacteria><Black><Black race><Caring><Characteristics><Chlamydia><Cities><Clinic><Clinical><Communities><Data><Decision Making><Disparities><Disparity><Doxycycline><Effectiveness><Enrollment><Ensure><Epidemic><Equity><Ethnic Origin><Ethnicity><Gender Identity><Geography><Goals><Gonococcal Infection><Gonorrhea><Guidelines><HIV><High Risk Woman><High-Risk Sex><Hour><Human Immunodeficiency Viruses><Incidence><Individual><Inequity><Interview><Knowledge><LAV-HTLV-III><Latine><Latinx><Long-term cohort><Long-term trends><Longer-term trends><Longerterm trends><Longitudinal cohort><Longitudinal trends><Longterm cohort><Longterm trends><Lymphadenopathy-Associated Virus><MSM><Methods><Miscellaneous Antibiotic><Miyagawanella><Modeling><Molecular><Nasal><Nasal Passages Nose><Nose><Participant><Pattern><Persons><Phenotype><Pneumonia><Population><PrEP><Prophylactic treatment><Prophylaxis><Provider><Public Health><Qualitative Methods><Race><Races><Randomization trial><Randomized, Controlled Trials><Recommendation><Recurrence><Recurrent><Research><Resistance><Respiratory System, Nose, Nasal Passages><Risk><S aureus><S. aureus><Safety><Sampling><San Francisco><Sexual Health><Sexually Transmitted Diseases><Sexually Transmitted Disorder><Sexually Transmitted Infection><Site><Staph aureus><Staphylococcus aureus><Subgroup><Survey Instrument><Surveys><Syphilis><Testing><Tetracyclines><Time><Unprotected Sex><Unsafe Sex><Venereal Diseases><Venereal Disorders><Venereal Infections><Vibramycin><Virus-HIV><access disparities><accessibility disparities><active followup><adolescent minority><ages><alpha-6-Deoxyoxytetracycline><anti-microbial resistant><arm><at-risk females><at-risk women><bedsonia><clinical relevance><clinically relevant><cohort><condomless intercourse><condomless sex><disparities in access><disparity in health><efficacy trial><enroll><ethnic minority><experience><females at high risk><follow up><follow-up><followed up><followup><great pox><group of color><health disparity><high risk females><individual of color><inequality in access><inequity in access><inequity in accessibility><infection risk><literate><men having sex with men><men of color><men who have sex with men><men who have sex with other men><minority children><minority youth><pediatric minority><people of color><person of color><population of color><pre-exposure prophylaxis><qualitative reasoning><racial><racial background><racial minority><racial origin><randomized control trial><randomized trial><resistance to anti-microbial><resistant><resistant to antimicrobial><sex><sexual encounter><sexually acquired infection><tool><trans-women><transgender women><transwoman><transwomen><unprotected intercourse><uptake><women at high risk><young minority>