Diaphragms, hoped to be a new solution in preventing HIV/AIDS infection, have proven to be ineffective, adding to the list of failed HIV prevention trials.

A study conducted in South Africa and Zimbabwe on the effectiveness of the diaphragm as a means of protection against HIV infection for women has come to a discouraging conclusion.

The diaphragm offers no additional protection against the virus. The rate of HIV infection was the same whether women used a diaphragm along with condoms or just condoms, Nancy Padian, Ph.D., of the University of California at San Francisco, and colleagues said.

The study, published online Friday in British medical journal The Lancet, was carried among nearly 5,000 women, over two years.

Of these 2,472 were provided with diaphragms and condoms; 158 became infected with HIV.

The other 2,476 women were given only condoms; 151 became infected, results showed.

Diaphragms are thought to protect especially vulnerable cells in the cervix.

Methods that have been proved to work efficiently in preventing HIV infection are condoms and circumcision; both are decisions to be taken by men. In Africa, they often object to using condoms and put their female partners at risk.

A previous prevention method that was explored eventually turned out to be ineffective: a microbicide gel. Trials in Asia and Africa were terminated in February this year, after studies showed that an active ingredient in the gel had the opposite effect of increasing the risk of HIV infection.