FILE - In this May 10, 2012, file photo, a doctor holds Truvada pills at her office in San Francisco. New research shows more promise for using AIDS t... FILE - In this May 10, 2012, file photo, a doctor holds Truvada pills at her office in San Francisco. New research shows more promise for using AIDS treatment drugs, such as Truvada, as a prevention tool, to help keep uninfected people from catching HIV during sex with a partner who has the virus. Truvada has been shown to help prevent infection when one partner has the virus and one does not, but the evidence so far has been strongest for male-female couples. (AP Photo/Jeff Chiu, File)

New research shows more promise for using AIDS treatment drugs as a prevention tool, to help keep uninfected people from catching HIV during sex with a partner who has the virus.

In one study, there were no infections among gay men who used a two-drug combo pill either daily or just before and after sex with someone with HIV.

In a second study, no uninfected men caught the virus if they had sex only with a partner whose HIV was well suppressed by medicines.

Both studies were discussed Tuesday at the International AIDS conference in Amsterdam.

There is no AIDS vaccine, so other prevention methods are crucial to curb the epidemic. About 36 million people worldwide have HIV and 1.8 million new infections occur each year.