Tenofovir prophylaxis linked with reduced risk of herpes simplex 2

1. Daily oral pre-exposure prophylaxis (PrEP) with tenofovir alone or in combination with emtricitabine in heterosexual individuals in high-risk populations was associated with a reduced risk of acquiring herpes simplex 2 (HSV-2). 

Evidence Rating Level: 1 (Excellent)

Study Rundown: PrEP with tenofovir with or without emtricitabine has been associated with protection against new HIV-1 infection in high-risk populations.  In vitro studies have also shown that intravaginal tenofovir gel is associated with reduced transmission of HSV-2.  Thus, this secondary analysis of randomized trials of tenofovir PrEP with or without emtricitabine for prevention of HIV sought to determine if this drug could also protect against HSV-2 infection in high risk populations.  The study found that daily oral dosing of tenofovir in high-risk populations was associated with a reduction in the rate of HSV-2 acquisition compared to placebo (hazard ratio 0.70, p0.047).  Interestingly, they found that PrEP was more protective against HSV-2 seroconversion in people whose HIV-1 positive partners were less immune-compromised with CD4 counts ≥0.350 x 10⁹ cells/L.  A major strength of the analysis was the high degree of adherence to the treatment, which was unique compared to other trials of daily oral tenofovir.  However, the study is limited by its design as a secondary analysis of data from prior studies that were not devised to study HSV-2 infection.

Click to read the study, published today in the Annals of Internal Medicine

Relevant Reading: Antiretroviral prophylaxis for HIV prevention in heterosexual men and women

In-Depth [secondary analysis]: This study was a secondary analysis within the larger (Partners PrEP) study of 4747 HIV-1 serodiscordant couples in Kenya and Uganda that were randomized to receive tenofovir (TDF), emtricitabine-tenofovir (FTC-TDF) or placebo. Within each of the three cohorts, individuals who did not have HIV-1 or HSV-2 at baseline were tested for their HIV-1 and HSV-2 status at 1, 3, 6, 12, 18, 24, 30, 36 months afterward. Of the 1498 people that were followed, 131 people developed HSV-2 positive status over 36 months of follow up. There was a statistically significant 30% reduction in incidence rate between those who received PrEP and those receiving placebo.  The incidence rates were 5.6 and 7.7 per 100 person-years respectively (P=0.047).  It was also noted that PrEP was more effective at reducing the occurrence of new HSV-2 infection in individuals who were with a less immune-compromised HIV-1 infected partner (CD4 count ≥0.350 x 10⁹ cells/L).

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Image: PD 

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