CNS: Combination Prevention: Can it turn the HIV tide?

If we really want to turn the HIV tide, we cannot afford to wait for a 'magic bullet', but do a better job with a broad range of HIV prevention and treatment tools and approaches at hand. The good news is that there is a growing list of evidence-based HIV prevention approaches that should be scaled up without delay to turn the tide (along with treatment and care). The bad news is that highly effective HIV vaccines may not be coming so soon. The sooner vaccines come, the earlier we can put the 'nail in the coffin' of eliminating HIV (provided we implement non-vaccine modalities of HIV prevention and care 'really really well'), said Dr Anthony Fauci, Director, National Institute of Allergy and Infectious Diseases (NIAID), National Institute of Health (NIH), USA, at the AIDS Vaccine 2012.

COMBINATION PREVENTION

We know to a considerable extent what works to reduce the risk of HIV transmission in different contexts. Harm reduction measures, condom use, prevention of mother to child transmission of HIV (PMTCT), early diagnosis and treatment of sexually transmitted infections (STIs), voluntary medical male circumcision (VMMC), testing and counselling, education, drug/ alcohol treatment, blood screening and other blood safety measures, Pre-Exposure Prophylaxis (PrEP), treatment as prevention, among others are some of the very effective and proven interventions to arrest HIV spread. What Dr Fauci advocates is to do combination prevention as well as possible without delay. He added, each of the components of combination prevention, "has to do something with bio-medical prevention and behaviour."

Dr Kenneth H Mayer, Medical Research Director and co-chair, The Fenway Institute; Director of HIV Prevention, Beth Israel Deaconess Hospital; and Visiting Professor, Harvard Medical School, strongly advocated for combination prevention. He said to Citizen News Service (CNS) that combination prevention has already shown to work. In all researches conducted so far, be it research on microbicides, oral pill (PrEP) or vaccines, the product-under research was combined with other proven modalities of HIV prevention such as quality counselling for safer sex practices, condom provision, regular screening and treatment for STIs, among others. Combination prevention works.

"We have proof of concept in humans that antiretroviral drugs for prevention can work (HPTN-052 study). We have the CAPRISA-004 study to show that anti-HIV vaginal gel (microbicides) can work and we have several oral PrEP studies for men who have sex with men (MSM), and for heterosexual men and women, in Africa. But in all these studies none of the products was 100% effective – even the strongest study, HPTN-052, didn't show 100% effectiveness. Also in HPTN-052 study, HIV sero-discordant stable couples (one partner was infected with HIV, and the other wasn't) who had the motivation to take the medication, were enrolled. The study participants received a lot of counseling in all these studies, so it is always combination prevention in these studies that is so key" said Dr Mayer.

"Likewise if we rely on antiretroviral medication for prevention we have to first convince people to take it. So some people may be in denial or ignorant of their HIV risk so part of the combination is testing people whether they are uninfected and people who are not infected to assess their patterns of risk to figure out what’s the best protection they will benefit from, counsel them to be adherent to the medication and to minimize other kinds of risk taking – so it is always a combination even now – it is not just the pill but it is the pill plus behaviour interventions" said Dr Mayer.

Dr Mayer added: "Part of the research now is that what is the least amount of medication one can use, can one use a gel or pill right before or after sex, so there is still the question of how can we use less medication for prevention, because lot of people are not risky every day! Another question for researchers is try to find the right medication. Many studies so far have used the tenofovir + FTC, and results show that it is a very well tolerated medication – which does have side effects on kidney and bone and is also the mainstay of treatment. Also with different populations there might be different delivery modes that will be beneficial – do we have to rely on a pill or a gel or can we use a ring or an injection so the field is going to take a long time to figure this out."

Just like antiretrovirals (ARVs) for prevention, vaccine field is at a very early stage. Thailand's RV144 HIV vaccine study gave the first proof of concept in 2009 although effectiveness was low (31%). Dr Fauci replied to a question raised by CNS at a press conference in Boston that even if the RV144 study that is currently being replicated in South Africa gave the same effectiveness as the Thai 2009 study (31%), US FDA is unlikely to license it for use.

COMBINATION STUDIES

Dr Mayer advocates for research studies that combine different HIV prevention tools such as studies that look at HIV vaccine candidates and PrEP (oral or topical use) for example.

Dr Anthony Fauci too said the same in the first plenary at AIDS Vaccine 2012. Dr Fauci referred to using an HIV vaccine together with non-vaccine combination prevention modalities in studies. He said that the bad news is that this will make HIV vaccine trial design more complicated but good news is that HIV vaccine efficacy need not be 95% in combination studies.

ACCESS

Another major learning of implementing health programmes around the world is that there is no magic bullet when it comes to access, especially access for populations most at risk of a given health problem. If we start scaling up all evidence-based HIV prevention, treatment and care tools and approaches as best as we can, and effectively address structural drivers of HIV, and barriers to services that are being rolled out, possibly we can bring the HIV infection rates very low, may be reach the proverbial 'zero'. And as Dr Fauci had said, when we do get a HIV vaccine as the years roll by, then it may be a final 'nail in the coffin to maintain elimination'. Till then, we have no excuse not to do all what's possible to turn the HIV tide.