Researchers are trying to figure out why the medication Truvada, which is used to treat people with HIV, isn't working in preventing HIV in women.
Last fall, the results of a clinical trial showed gay men who took it as a preventive measure had a 44 percent lower risk of getting HIV.
But a similar trial involving women in Southern Africa has been terminated early, after researchers found the pill didn't seem to work.
Steffanie Strathdee heads up UCSD's Division of Global Public Health.
"I think that what we are seeing is that we can't get rid of condoms, and we're going to always need to be promoting behavior change within the context of HIV prevention," Strathdee said.
Researchers will be looking into the data of the terminated trial to see if any useful information will emerge.
For example, it's unclear why women who took the pill had more pregnancies than women who took a placebo.
The pill is made by the Bay Area company Gilead Sciences.
