Argument: While not 100%-effective, condoms reduce risk of HIV-transmission
Marcella Alsan. "Catholic Church condom prohibition comes face to face with reality of AIDS in Africa". Catholic.com. 24 April 2006 - "Although it is true that condoms are not 100-percent effective in preventing HIV infection, they do reduce the risk of transmission significantly. Comparing condom use to a suicidal dare, as Cardinal Trujillo does, is scientifically inaccurate and socially irresponsible.
A preponderance of medical research demonstrates that condoms help prevent the spread of HIV. For example, the European Study Group on Heterosexual Transmission of HIV followed 124 discordant couples (in which only one of the pair is..."
AIDS statement from the French Conference of Catholic Bishops [“French Catholic Bishops Stray from Teaching on Condoms,” Catholic World Report, February 12, 1996]. - “Many competent doctors state that a viable condom is today the sole means of prevention. In this respect, it is necessary. The condom is thus understandable for cases in which a person who already engages in sexual activity needs to avoid a serious risk, just as we insist that this is not a substitute for an adult sexual education.”