How microbicide works & its efficacy

How Will They Work?

"Microbicide" is simply a common term put on anything created to prevent contamination by HIV and other sexually transmitted pathogens when applied in the vagina or rectum. Since HIV and STI (sexually transmitted infection) pathogens can attack your body in various ways, an effective microbicide should stop this attack at several stages in the infection process.

Each uses at least one of these five basic mechanisms of steps:
# Eliminating or inactivating pathogens.
Some microbicides work by breaking down the top or envelope of the virus or pathogen.

# Developing physical barriers.
Microbicides could give you a physical barrier between pathogens and vulnerable cells in the epithelium (cell wall) of the vagina or rectum.

# Building up your body's normal defenses.
The body has many naturally sourced immunity process that a microbicide may be able to supplement or boost.
Lactobacillus, for example, is a naturally occurring, "good" bacteria that can help protect the vagina by keeping its acidic environment.
This natural level of acidity allows an inhospitable environment for most pathogens, including HIV.
Therefore, a microbicide that supports the lactobacilli in performing this purpose is one potential procedure of action being explored.

# Inhibiting viral entry.
Some microbicides bind to viruses and bacteria in order to prevent them from binding to and infecting healthy cells.

# Suppressing viral replication.
Some microbicides are being developed from the antiretroviral medicines that HIV-positive people use to reduce the quantity of virus in their bodies.
Designed as gels or creams, these medicines may be able to restrain replication of HIV that enters the vagina or rectum during intercourse.
In that case, they could significantly lower the chances that the microbicide user will become infected or re-infected (if already HIV-positive).
Microbicides may also be combined with physical barriers for higher performance.

Studies are currently ongoing, for example, to find out if simply using a regular contraceptive diaphragm can help women minimize their HIV risk, considering that the diaphragm blocks off the cervix which is more susceptible to HIV infection than tissue on the lower area of the vagina.
Should this be true, then use of the diaphragm with an effective microbicide might offer women better protection than either method alone.
Given their partial efficacy, it will be crucial that the public health messages we develop around microbicides continue to encourage people to use condoms whenever possible.
Microbicides will be a risk reduction approach to safe sex.
For whom condom use just isn't happening, microbicides could be a method of lowering risk by half or more -- not an insignificant benefit when your only alternative is no protection at all.

How Effective Would They Be?

"Partial efficacy" is the expression used to explain a method that reduces, but will not eliminate, the risk of infection.
Microbicides are expected to be 50-60% effective against HIV.
Microbicides alone probably will never be as effective as correctly-used condoms, considering it is generally safer to keep a virus out of your body than it is to attempt to stop it once it's there.
But even a partially effective microbicide will function much better than a condom left in the drawer.
The main purpose of microbicides will be to provide a harm reduction option to people who are not able to insist on condom use and who currently have no way to protect themselves from contamination or reinfection.