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  IAS 2019: Conference on HIV Pathogenesis
Treatment and Prevention
Mexico City
July 21-24 2019
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Almost No New HIV Infections in Paris
Comparison of Daily vs As-Needed PrEP

  10th IAS Conference on HIV Science (IAS 2019), July 21-24, 2019, Mexico City
Mark Mascolini
A nonrandomized study of more than 3000 Paris-area people at risk for HIV infection detected only 2 new HIV cases with daily or as-needed Truvada preexposure prophylaxis (PrEP) through an average 8.7 months of follow-up [1]. Both people who became infected had stopped as-needed PrEP for several weeks.
The double-blind placebo-controlled French IPERGAY trial established the effectiveness of as-needed (or "on-demand") PrEP (doses only before and after sex) in men who have sex with men (MSM) at high risk for HIV infection [2]. To learn more about how well before-and-after-sex PrEP works in the community compared with traditional daily PrEP, a French team mounted the open-label nonrandomized Prevenir cohort study [1].
Prevenir aimed to recruit at least 3000 HIV-negative adults at high risk for HIV infection in the Paris region. "High risk" meant active sex and inconsistent condom use. Participants could choose either as-needed or daily PrEP and could switch to the other option during follow-up. Every 3 months participants got tested for HIV with a fourth-generation ELISA. The study goal was to demonstrate a 15% lower rate of new HIV infections with PrEP over 3 years than would be expected among MSM in the Paris area.
By May 2, 2019, researchers had enrolled 3057 participants across 26 sites, 98.7% of them MSM, 85.5% white, and 55% with no regular sex partner. Median age stood at 36 years. The group had a median of 2 condomless sex acts in the past 4 weeks and a median of 10 sex partners in the past 3 months. About half of participants (49.2%) opted for as-needed PrEP. Through 18 months of follow-up, the Prevenir team recorded almost no shift in percentage of participants switching to the alternate regimen. Rates of correct PrEP use were high in both the as-needed and daily PrEP groups (96.4% and 97.5%). Condom use was low in both groups, 21.9% on as-needed PrEP and 18.8% on daily PrEP.
Through an average 8.7 months of follow-up (2208 person-years), 2 participants got infected with HIV to yield an incidence of 0.09 cases per 100 person-years (95% confidence interval 0.01 to 0.33). Both infected people signed up for the as-needed PrEP group: one had stopped PrEP 10 weeks before becoming infected and the other had stopped 7 weeks before infection. The incidence difference between the as-needed group and the daily group did not reach statistical significance (P = 0.132). The researchers figured that PrEP had averted 143 HIV infections in the study population.
Risky sex became more frequent by a few measures when participants started PrEP: At 3 months average number of sex acts in the past 4 weeks rose 43%, percentage of condomless sex acts during last intercourse rose 21%, and percentage of receptive condomless sex acts during last intercourse climbed 15% (all P < 0.001). Average number of sex partners in the past 3 months fell 20% (P < 0.001). Participants using daily PrEP had more partners, more condomless sex, and a higher incidence of bacterial sexually transmitted infections (STI).
Overall bacterial and viral STI rates were high. Clinicians diagnosed 23 cases of viral hepatitis in 23 people, usually HCV infection (1.04 cases per 100 person-years). Bacterial STI incidence rose an estimated 38% yearly, with anal gonorrhea climbing 48% per year and anal chlamydia/gonorrhea jumping 47% per year (P < 0.001 for all increases).
The drug-related adverse event rates was marginally higher with as-needed PrEP than with daily PrEP (13.2 versus 11.4 per 100 person-years), as were PrEP discontinuations due to drug-related adverse events (0.3 versus 0.0 per 100 person-years). But the grade 3 or 4 adverse event rate was lower with as-needed PrEP (4.4 versus 5.3 per 100 person-years).
Prevenir investigators believe their findings confirm the high efficacy of both daily and as-needed Truvada PrEP. They stressed the high retention rate in this prospective cohort, with 196 of 3057 people dropping out (8.9 per 100 person-years).
1. Molina JM, Ghosn J, Algarte-Genin M, et al. Incidence of HIV-infection with daily or on-demand PrEP with TDF/FTC in Paris area: Update from the ANRS Prevenir study. 10th IAS Conference on HIV Science (IAS 2019), July 21-24, 2019, Mexico City. Abstract TUAC0202.
2. Molina JM, Capitant C, Spire B, et al. On-demand preexposure prophylaxis in men at high risk for HIV-1 infection. N Engl J Med. 2015;373:2237-2246. http://www.natap.org/2015/HIV/120915_03.htm