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Microbicides - new hope for HIV/AIDS prevention
Reprinted courtesy of IRIN PlusNews, 15 May 2002.
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An effective microbicide which can prevent or reduce HIV transmission could have a dramatic effect on the course of the HIV/AIDS epidemic, its supporters claim.
The following is a PlusNews Briefing to mark the Microbicides 2002 conference under way this week in Antwerp, Belgium attended by over 650 researchers, activists, clinicians and people living with HIV/AIDS from 44 countries.
What Are Microbicides?
A microbicide is a substance that prevents the transmission of diseases. Microbicides work by killing or disabling a germ or virus. Microbicides can be administered via a gel, cream, suppository, film, sponge, wipe and vaginal or rectal ring.
A microbicide can work by killing the bacteria or virus. Alternatively, a microbicide may prevent the replication of the virus or bacteria after infection has occurred. A microbicide could also use the barrier method by serving as an "invisible condom" applied to the vagina or rectum to block infection by bacteria or a virus.
Are they available now?
Not yet. There are about 60 microbicide products and compounds currently under investigation in small biopharmaceutical companies, non-profit organisations and smaller public companies. Eleven microbicide candidate products have shown enough promise to be approved for human testing in clinical trials.
According to a series of reports by the Rockefeller Foundation-funded Initiative on Microbicides, it is likely that one or more of these products could be commercially available by 2007, depending on trial outcomes and adequate funding.
A barrier to microbicide research and development is the lack of interest and investment by large pharmaceutical companies. Presently, no major pharmaceutical company is investing in microbicide research and development. These companies are reluctant to get involved because of concerns about scientific and regulatory uncertainty and competing opportunities to invest in products that are potentially more profitable.
Would you still need to use a condom?
When used consistently and correctly, condoms are likely to provide better protection against HIV and sexually transmitted infections (STIs) than microbicides, so they will still be the preferred option. But microbicides would fill an important prevention gap for those who cannot or will not use condoms.
What if a woman wants to get pregnant?
Some microbicides may be contraceptives and others may not. This will give positive women who want to have children the ability to do so with less risk to an HIV-negative partner. Contraceptive microbicides would give women another way to avoid an unwanted pregnancy.
With time, it may be possible to formulate a microbicide as a vaginal wash to help prevent mother-to-child transmission of HIV during childbirth, as an addition or back-up to antiretroviral interventions. Microbicide researchers are also investigating a compound that could be added to breast milk to make it safe for infant feeding.
How would they benefit women who are already HIV positive?
Microbicides could help protect women from sexually transmitted and vaginal infections other than HIV, which can pose an even larger danger
when one?†s immune system is challenged. A broad-acting microbicide against multiple STIs would help prevent these dangerous infections in
HIV-positive women, and may even promote healthy vaginal conditions to ward off yeast infections.
Several potential microbicides are undergoing specialised trials in order to prove they are safe for positive women to use.
What about men?
Many candidate microbicides currently being tested will provide "bi-directional" protection, helping protect men as well as their partners. A new report published by the American Foundation for AIDS Research focuses on the need for microbicides that could prevent HIV transmission during anal sex. Condoms provide the best barrier against rectal infections but rectal microbicides could offer protection in the absence of condoms as well as giving back-up protection when condoms are being used.
Although most of the clinical microbicide trials focus on vaginal use of the products, men are also involved in microbicide research. Once a
product is determined to be safe for vaginal use, men are enrolled in "male tolerance" trials to see if the product causes irritation to the penis or the male urethra.
Would the products be widely available and easily accessible?
In 2001, the Rockefeller Foundation convened a working group to explore what needs to happen to ensure that microbicides will be available and
affordable to those who need them, and that individuals have the knowledge, skills, power, and social support necessary to use them.
The resulting document, "Preparing for Access and Use," lays out a plan of research and action to ensure that microbicides are readily available in outlets convenient to potential users, especially in developing countries, and that cost is not a barrier to microbicide use. The document concludes: "It is inefficient, and even unethical, to repeat the mistakes of the past that have forced individuals in the developing world to wait years, sometimes decades, to gain access to much-needed drugs or vaccines."
Would people be willing to use the product?
In acceptability studies conducted in Zimbabwe, Uganda, and South Africa, both women and men expressed willingness to use microbicides. Formulation preference studies also suggest that no one formulation or delivery device will meet the needs and preferences of all women. Some prefer gel applied with an applicator; others may opt for film, suppository, or sponge.
What about cultural practices such as dry sex?
In some parts of sub-Saharan Africa, women routinely use various cleaning and drying agents before sex in order to dry or tighten the vagina. This practice - known as "dry sex" - stems from the belief that men prefer a tight, dry vagina. In some instances, sexual lubrication is also associated with promiscuity. It is still not clear whether women will be able to use lubricating agents when male partners expect "dry sex" and vaginal wetness can be perceived as a sign of infidelity or infection.
(Sources: Global Campaign for Microbicides and GENDER-AIDS discussion forum. To read the HDN Key Correspondent Team coverage of Microbicides 2002: http://www.hdnet.org)
[This item is delivered to the English Service of the UN's IRIN humanitarian information unit, but may not necessarily reflect the views of the United Nations.] |
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