CNS: HIV prevention needs more tools such as microbicides

Vaginal and anal sex continue to put millions of people at risk those who are unable to use or negotiate the use of existing HIV prevention options. Microbicides although currently under research, are being seen as an important new HIV prevention tool that will expand the range of prevention options for men and women. Rectal and vaginal microbicides are antimicrobial agents formulated as gels, creams, films, or suppositories for application to the vagina or rectum for the prevention of HIV transmission, and/or other sexually transmitted infections (STIs). Microbicides have various modes of action like killing/ inactivating the pathogen by disrupting the viral envelope; strengthening the vagina's defence system and maintaining acidic pH; strengthening the rectum's defence system, creating a physical barrier between the pathogen and target; preventing infection spread to other cells by blocking viral replication within cells.

Despite the availability of several prevention strategies, HIV continues to spread at an alarming rate, especially among those women and men who aren't able to use or negotiate the use of existing HIV prevention options with their partners. HIV prevention programmes all over the world have promoted the use of male condoms and millions of at-risk women and men have to depend on their (insertive) partner’s decision about their use. Microbicides can empower a receptive woman or man to protect both sexual partners from HIV and/or other STIs. They can have an additive effect if used in conjunction with barrier methods like male and female condoms.

An ideal microbicide needs to have certain properties. It must be safe and non-toxic, efficacious and well tolerated, inexpensive, easily applicable, widely acceptable, colourless and odourless, and available in both contraceptive and non contraceptive forms.

Anna Forbes, the 2012 Omololu Falobi Awardee and a noted women rights’ activist, asserts, “I think that the single biggest thing which safe and effective microbicides will do is to give women the power to protect themselves in a way that does not involve their partners, and now that the majority of new infections in the world are occurring among women, this is going to bring a dramatic change.”

“It is important that microbicides be produced in both contraceptive and non contraceptive forms so that women who want to become pregnant still have the ability to protect themselves. Otherwise they are more likely to be used by women who do not want to become pregnant. If women need contraception, they can buy one that protects them from HIV infection too, and not purchase two separate products. On the other hand for women who want to become pregnant, they would avoid something that includes a contraceptive. So it is important that we have non contraceptive brands as well. Also right now most of the candidates being examined include anti retro viral (ARV) drugs. A woman has to be sure that she is HIV- before being able to use an ARV based microbicide. But women who are HIV+ will not be able to use ARV based microbicides because it would interfere with their treatment regimen and it could also cause HIV drug resistance. So non ARV based microbicides will be very important for women living with HIV who need to protect a partner and also to protect themselves from a secondary infection of the virus.”

Dr. Badri Saxena, President, Microbicides Society of India (MSI) and Chairperson of Microbicides Expert Group of Indian Council of Medical Research (ICMR)/ Department of Health Research (DHR), feels that, “There is not one preventive product for HIV. There have to be several tools available- microbicides, vaccines and in some cases male circumcision. And there has to be better use of existing methods like male and female condoms. When there was a big epidemic of HIV-AIDS in the 80’s America turned the tide by effective use of barrier preventive products like condoms and safe sex practices. For countries like India, Africa and China our healthcare delivery system has to be energised. We have to improve the implementation/ effectiveness of existing technologies, and then work for newer technologies. This requires training of manpower, more public participation and safe sexual practices and behaviour. In a place like India several studies have shown that in several marriages it is generally men who bring HIV to their wives. Circumcision in our country is not likely to work because it is restricted to Muslim and Jewish communities. So microbicides can be an effective method. In India non HIV STIs, like Human Papilloma Virus (HPV) and cervical cancer are a big problem with an estimated 3 million people suffering from them every year. They are at-risk for HIV, so better control of such infections is more essential to prevent HIV in the country. New technologies are welcome because no one method suits all, and it is for men and women who are most at risk to choose.”

Currently, around 60 products are at various stages of the research pipeline, from phase I to phase III trials. At least eleven of them have already been found to be safe and efficacious in animal studies, and have recently been started to be tested on humans. Anna elaborates, "There is a product that is going into the phase III trial-- the vaginal ring that is similar to the NuvaRing contraceptive device currently on the market -- except this one will carry a microbicide. It is a small plastic hollow ring device that a woman can insert into her vagina and it slowly releases a microbicidal drug over a period of a month. At the end of the month she can take it out and insert a new one. It is not like something that has to be inserted in the uterus or has to be applied just before sex, thus making it more user friendly for women. There are other ARV and non ARV based microbicides too that are in the earlier pre clinical stages of development.”

For Manju Chatani Gada of AVAC: Global Advocacy for HIV Prevention, “Microbicides add another tool for HIV prevention. Pre exposure prophylaxis using ARVs in who are HIV negative people, voluntary male circumcision for HIV prevention, and treatment as prevention where an HIV+ individual uses treatment as a prevention of transmission to their partners are three interventions where we have seen fantastic results and the challenge is really to scale them up. But one thing we have learnt is that one size does not fit all and one tool does not suit all. So in HIV too we need as many tools as possible, so that people can pick and choose what works for them to prevent HIV acquisition and transmission. Microbicides will give us what we have really been looking for, as additional tools to prevent HIV, along with existing interventions like male/ female condom use, limiting partners, loyalty relationships. They have the potential of becoming a major intervention for HIV control in the coming decades and may play a crucial role in turning the tide of the AIDS pandemic.”

The forthcoming XIX International AIDS Conference (AIDS 2012) is on the theme of 'turning the tide together'. Let's hope that the governments and other stakeholders will continue to accelerate vaginal and rectal microbicide research and development and help turn the tide of HIV.