Clinical Outcomes of Acute HIV at Initiation of PrEP, PEP

A team of investigators sought to identify patients with undiagnosed acute HIV infection when PrEP/PEP was initiated.

Acute HIV infection (AHI) was determined to be a rare occurrence in patients initiating pre-exposure prophylaxis (PrEP) and post-exposure prophylaxis (PEP), and 23% of patients with AHI developed emtricitabine-related M184 mutations, according to a retrospective case series analysis published in the Journal of Acquired Immune Deficiency Syndrome.

Researchers examined 4000 adult patients who started PrEP from January 2012 to December 2018 or PEP from January 2011 to December 2018 at the San Francisco City Clinic to identify those with undiagnosed AHI on the day treatment was initiated. AHI was defined as negative rapid HIV antibody testing and pooled HIV RNA detected.

The following were conducted for eligible patients interested in initiating PrEP/PEP:

  1. Initial HIV testing with a rapid point-of-care antibody test
  2. If rapid antibody test were negative, PrEP/PEP was initiated while blood sample was sent to laboratory for pooled HIV RNA testing
  3. If HIV RNA testing were positive, immediate linkage to HIV care was offered
  1. Prophylactic therapy was stopped in patients on 2-drug prophylactic therapy
  2. Prophylactic therapy was continued in patients on 3-drug PEP therapy

The investigators found that 13 (0.3%) of patients had undiagnosed AHI at the time of initiation of prophylactic therapy: 7 among PrEP patients and 6 among PEP patients. These patients had successful linkage to HIV care; 12 (92.3%) started antiretroviral therapy and 11 (84.6%) achieved viral suppression. In addition, all 13 patients with undiagnosed AHI were men who identified as being gay with a median age of 29 years, which suggests patients with these risk factors should be screened for AHI at the beginning of care and encouraged to start PrEP.

Emtricitabine-related M184 mutations were identified in 3 (23%) patients with AHI from 2012 to 2013. Stored serum samples determined a wild-type virus prior to PrEP/PEP initiation, showing that the M184 mutation had developed within 7 to 12 days of PrEP/PEP exposure. These 3 patients were linked to HIV care, began antiretroviral therapy, and achieved viral suppression within 6 months. Study authors noted none of the patients had tenofovir-associated K65R mutations.

Limitations of this study include an inability for the long-term clinical outcomes to be generalizable because this study was performed at a single clinic, possible nonadherence contributing to lack of drug resistance mutations observed due to medication adherence not being recorded from the day of PrEP/PEP initiation to the day of HIV disclosure or resistance testing, and an inability to confirm that HIV resistance mutations were the result of PrEP/PEP initiation

This case series analysis highlighted the significance of screening for AHI in patients at the time of PrEP/PEP initiation, specifically in programs prescribing same-day PrEP therapy. “Overall, our results offer reassurance that the benefits of same-day PrEP prescribing outweigh the risks associated with initiating PrEP in the setting of AHI, provided systems are in place for early diagnosis and connection to HIV care,” the study authors concluded.


Johnson KA, Chen M-J, Kohn R, et al. Acute HIV at the time of initiation of pre or post exposure prophylaxis: impact on drug-resistance and clinical outcomes. J Acquir Immune Defic Syndr. Published online January 28, 2021. doi:10.1097/QAI.0000000000002638