Acute HIV at the Time of Initiation of Pre-Exposure or Post-Exposure Prophylaxis

Impact on Drug Resistance and Clinical Outcomes

Kelly A. Johnson, MD, MPH; Miao-Jung Chen, PhD, MPH; Robert Kohn, MPH; Darpun Sachdev, MD, MPH; Oliver Bacon, MD, MPH; Sulggi Lee, MD, PhD; Stephanie E. Cohen, MD, MPH


J Acquir Immune Defic Syndr. 2021;87(2):818-825. 

In This Article


Study Setting and Design

San Francisco City Clinic (SFCC) offers free and low-cost sexual health services including HIV/STD screening, diagnosis, and treatment alongside PrEP and PEP.[14,15] We identified all adult (18+ years old) SFCC patients—regardless of gender, race, sexual orientation, or any other demographic characteristic—who started PEP from January 2011 to December 2018 or PrEP from January 2012 to December 2018. Study dates were selected to account for the years during which two-drug PEP and PrEP were offered at SFCC and to allow for at least 2 years of follow-up time for each patient. Patients (n = 300) prescribed PrEP at SFCC between 2012 and 2013 as part of the US PrEP Demonstration Project, a study assessing the feasibility, safety, and acceptability of PrEP delivery within STD clinics,[16] were included in the study population for this analysis.

From within the larger population of patients who initiated PrEP or PEP at SFCC during 2011–2018, we identified all patients who had undiagnosed AHI on the day that PrEP or PEP was started (with AHI defined as rapid HIV antibody negative and pooled HIV RNA detected). We conducted a detailed chart review of this subset of patients.

At SFCC, HIV PrEP (combination TDF/FTC) is offered to any patient on request and to those who report specific behaviors such as condomless anal sex, sex with an HIV-positive partner, or injection drug use. PEP is offered to patients not on PrEP who report a possible exposure to HIV within the previous 72 hours.

The specific regimens prescribed for PEP were (1) before September 2012: zidovudine/lamivudine (AZT/3TC) alone, (2) from September 2012 through May 2016: combination TDF/FTC, (3) from May 2016 through August 2017: 3-drug therapy with TDF/FTC plus raltegravir, and (4) from August 2017 to present: primarily either TDF/FTC plus dolutegravir (DTG) or bictegravir/emtricitabine/tenofovir alafenamide (BIC/TAF/FTC).[15] PrEP and PEP navigators enroll patients in patient assistance programs to ensure that all patients have access to free or affordable PrEP or PEP. No strong evidence exists, based on randomized clinical trials, that any specific combination of antiretroviral medication is optimal for PEP use.[17] BIC/TAF/FTC has been shown to be safe and tolerable for PEP.[18] Its use for this indication is supported by expert opinion,[19] as it requires enrollment in only 1 patient assistance program and affords the convenience of a single-tablet regimen to optimize PEP adherence.

Within the SFCC PrEP/PEP program, eligible patients interested in starting either PrEP or PEP receive initial HIV testing with a rapid point-of-care antibody test (2011–March 2012: OraQuick Advance, Orasure technologies; March 2012-present: Clearview HIV 1/2 STAT-PAK, Alere). If this test is negative, patients are started on PEP or PrEP while their drawn blood is sent to the San Francisco Department of Public Health's (SF DPH) laboratory for pooled HIV RNA testing (Abbott Diagnostics m2000 RealTime HIV-1 assay; Abbott Laboratories, Abbott Park, IL) to identify cases of AHI.[15] Patients prescribed 2-drug prophylactic therapy (whether with PrEP or with 2-drug PEP when this was the standard of care at SFCC before May 2016) are asked to stop their prophylactic therapy and offered immediate linkage to HIV care at the time of results disclosure if they test positive for HIV. Patients prescribed 3-drug PEP are asked to continue their current antiretrovirals (which can also serve as complete HIV treatment regimens) through linkage to HIV care.

Data Collection and Statistical Analyses

For the subset of patients who had undiagnosed AHI on the day of PrEP/PEP start within our study dates, we used electronic medical records at SFCC and the local Department of Public Health–affiliated county hospital (Zuckerberg San Francisco General) to gather clinical and behavioral information for each patient at the time of their HIV diagnosis including (1) age, (2) sexual orientation, (3) specific regimen prescribed for PrEP or PEP, (4) self-reported time since last sexual encounter, and (5) self-reported sexual behaviors in the past 3 months (total number and gender of sexual partners, as well as number of partners with whom each patient engaged in condomless receptive anal sex).

Laboratory data collected for each patient at or around the time of AHI diagnosis included rapid HIV test result, first HIV viral load, CD4 lymphocyte count, and genotype (where available by chart review) as well as any documented bacterial sexually transmitted infections (STIs) such as gonorrhea, chlamydia, or syphilis of any stage within the preceding year. Where available, we also collected information on each patient's HIV viral load trend and HIV treatment regimens from time of diagnosis to present (as of December 2020).

HIV-1 genotyping and clinical outcome data were also obtained from the SF DPH HIV surveillance registry and eHARS (enhanced HIV/AIDS reporting system), respectively. Clinical outcome data included time to linkage to HIV care, time to initiation of antiretroviral therapy, time to viral suppression, and most recently known HIV treatment regimen as of December 2020. In accordance with SF DPH surveillance definitions, date of AHI diagnosis was defined as the date when a specimen was collected for pooled HIV RNA. Time to linkage to care was defined as the number of days between a patient's initial HIV diagnosis and when they first had laboratory test results (such as repeat HIV viral load and CD4 count, serving as a proxy of an HIV care visit) reported to public health surveillance.[20] Time to viral suppression was defined as the number of days between HIV diagnosis and an HIV viral load less than 200 copies/mL in eHARS.

Summary statistics such as median and interquartile range (IQR) for numeric variables were calculated using STATA version 16.0. This study was reviewed by the Institutional Review Board (IRB) of the University of California San Francisco (UCSF) and received a designation of exempt.