Pre-Exposure Prophylaxis for Prevention of HIV Infection

June 21, 2015

This column first appeared in the Zambia Post.

Three years ago, the HIV and AIDS world received news that the authoritative US Federal Drug Authority (FDA) had approved the use of the antiretroviral combination pill Truvada by HIV negative people to reduce the risk of acquiring HIV infection (Truvada combines the two ARVs Tenofovir and Emtricitabine and is often shortened to TDF/FTC).

Within days of this announcement, the WHO issued its GUIDANCE ON PRE-EXPOSURE ORAL PROPHYLAXIS (PrEP) FOR SERODISCORDANT COUPLES, MEN and TRANSGENDER WOMEN WHO HAVE SEX WITH MEN AT HIGH RISK OF HIV: Recommendations for use in the context of demonstration projects.

The FDA approval, and the WHO guidance, followed results from clinical trials that showed that the daily taking of ARVs (specifically Truvada) by HIV negative people (men and women) exposed to HIV infection, significantly protected them from the acquisition of the virus.

One such study, the PARTNERS PrEP Trial, was done in Uganda and Kenya and involved 4,758 HIV-discordant couples (in which one partner was HIV infected and the other negative). The trial showed that if the HIV negative partner took daily Truvada, they were 75 percent less likely to become infected (than those who took a daily pill that did not contain Truvada or any other ARV). Adherence to taking the Truvada daily was important in improving the protection it offered. Amongst those HIV negative partners who showed that they were complying with taking the drug daily (as demonstrated by the presence of detectable medicines in their blood, PrEP reduced their risk of HIV infection by 90 percent).

Another study, known as the iPrEx Study, was also done among men and transgender women who have sex with men. It was done in Peru, Brazil, Thailand, South Africa and the United States. In that study, those HIV negative people who were given PrEP were 44 percent less likely to get HIV infection, than those who were not. In those men who took their pills consistently (as evidenced by blood tests) PrEP reduced their risk of HIV infection by as much as 92 percent.

The clinical trials demonstrated that taking the PrEP consistently daily is key to achieving high levels of protection from infection.

In its guidance on PrEP, the WHO was characteristically cautious in its advice to governments, stating: “Although the evidence of effectiveness is strong, it remains unclear how PrEP may be implemented and scaled up in settings where its use might be most beneficial.”

The guidance also stated that WHO was encouraging countries to undertake demonstration projects, and would “offer advice on key questions and areas that could be addressed to facilitate understanding of the safety, effectiveness and sustainability of oral PrEP, and its use as an addition to existing HIV prevention efforts”.

“The outcome of these demonstration projects and country experience will also be used by WHO in 3 to 5 years time to develop guidance for the implementation and scale up of PrEP,” the 2012 WHO guidelines promised.

The guidelines’ specific recommendation on PrEP for serodiscordant couples says: “In countries where HIV transmission occurs among serodiscordant couple, where discordant couples can be identified and where additional HIV prevention choices are needed, daily oral PrEP (specifically tenofovir or the combination tenofovir and Emtricitabine) maybe considered as an additional intervention for the uninfected partner”.

In May last year, the United States’ Public Health Service released its comprehensive clinical practice guidelines for PrEP called ‘Pre-exposure Prophylaxis for the prevention of HIV infection in the United States-2014″.

These guidelines stated at the end of a review of the PrEP trials in men and women; “Daily oral PrEP with TDF/FTC is recommended as one HIV prevention option for heterosexually active men and women at substantial risk of acquisition because these trials present evidence of its safety and to present evidence of efficacy in these populations, especially when medication adherence is high”.

Similar recommendations are made for sexually active MSM and injecting drug users.

Notably, both the WHO guidance and the CDC-led US Public Health Service clinical practice guidelines emphasize that PrEP cannot and should not be taken in isolation, or as replacement of existing prevention efforts and methods. Both stress that PrEP should be used as “one prevention option” that should be “an addition to existing HIV prevention efforts”. This is highly significant because even while on PrEP, HIV negative people should continue using condoms; reduce on multiple concurrent sexual partnerships etc.

So what are the implications of PrEP, prevention of new HIV infections in Zambia, and the general Zambian HIV and AIDS response?

Issues of the paucity or lack of domestic funding of our response aside, there is a deafening lack of noise on PrEP in our national HIV and AIDS conversation. Since the FDA approval and the subsequent issuance of WHO guidelines, we have heard more spoken around Option B+, Test and Treat, VMMC, sex work and sex workers, defining key populations, getting Zambia to zero new infections and so on. Even this column has referred to PrEP mostly in passing and in context of other HIV prevention subjects.

One wonders if perhaps the silence on PrEP has been fueled by the international publicity and discussion around the iPrEx study and its results implications for preventing HIV infections among men who have sex with men. Has Zambian officialdom’s fear of recognizing the existence of Zambian MSM and transgender people clouded or completely blacked out a potentially beneficial addition to our armamentarium of evidence-based and proven HIV prevention interventions?

Some of the seminal work on serodiscordance in married and cohabitating couples has been done here in Zambia. In our fear of addressing MSM issues and related HIV, are we denying serodiscordant couples in Zambia an intervention that is available now to similar couples in the US, using a drug combination that is available and approved for treatment in Zambia?

The least we can do and bring up to the public arena the fact that PrEP works is that we should be debating the pros and cons of its implementation as a nation!”