You are here
INITIATING PrEP DURING ACUTE HIV INFECTION: WHAT IS THE RISK FOR ARV DRUG RESISTANCE?
Donn J. Colby1, Chanjiraporn Pondet1, Tippawan Pankam1, Prapaipan Plodkratok1, Rapee Trichaviroj2, Carlo Sacdalan1, Eugène Kroon1, Siriwat Akapirat2, Jintanat Ananwora
1Thai Red Cross AIDS Research Center, Bangkok, Thailand,2Armed Forces Research Institute of Medical Sciences in Bangkok, Bangkok, Thailand,3US Military HIV Research Program, Bethesda, MD, USA
Pre-exposure prophylaxis (PrEP) is very effective at preventing HIV infection. However, there is risk for antiretroviral drug (ARV) resistance if the 2-drug PrEP regimen is given to individuals with acute HIV infection.
Individuals at risk for HIV infection were screened with 4th generation HIV antibody/antigen (4thG) testing at the Thai Red Cross Anonymous Clinic (TRCAC), the largest HIV testing center in Thailand, performing over 40,000 tests annually. PrEP (TDF/FTC) was offered as part of a combined HIV prevention package, and could be started the same day. Qualitative HIV RNA (Aptima HIV-1, Hologic, USA) was done on 4thG non-reactive specimens using pools of up to 17 specimens to identify acute HIV infection (AHI), with result available in 24-48 hours, and confirmation by quantitative HIV RNA (Roche AmpliPrep/Taqman v2.0). PrEP users had repeat HIV testing and counseling at 1 month, 3 months, and then every 3 months.
Through October 2018, 2,442 people started PrEP at the TRCAC; 93% were male and 83% were men who have sex with men (MSM). Median age was 32 (range 17-78) years. Seven individuals, or 1/350, had AHI at PrEP initiation. All 7 with AHI were MSM aged 22-39 years. AHI was identified by pooled qualitative HIV RNA in 5 cases; median quantitative HIV RNA was 317 (range 32-16,780) copies/mL. The remaining 2 cases were diagnosed by reactive HIV serology at the 1-month post-PrEP visit: in both the qualitative HIV RNA was negative, but quantitative HIV RNA on stored pre-PrEP specimens had detectable HIV RNA at 58-86 copies/mL. PrEP was used for a median 14 (range 2-121) days. ARV resistance data were available for 6 cases: 3 cases had single resistance mutations M184V/I, conferring high-level resistance to FTC. No cases had resistance mutations to TDF. The 3 cases that developed FTC-resistance took PrEP for 30, 34, and 121 days. The 3 cases without resistance mutations took PrEP for 2, 7, and 14 days.
AHI at PrEP start occurs in 1/350 PrEP users at the TRCAC. Qualitative HIV RNA on pooled samples will identify most, but not all cases of AHI. If AHI is identified early, immediately initiating 3-drug antiretroviral therapy (ART) can prevent ARV drug resistance. FTC resistance begins to emerge after 2-4 weeks of PrEP use. There appears to be lower risk for resistance to TDF. If HIV infection occurs during PrEP use, ARV resistance testing should be performed and ART started immediately.