Bob Roehr (doi:10.1136/bmj.b311) says that the current ban on blood donations from gay men is not supported by evidence, but Jay P Brooks says that the risk of transmission of infection is too great

New HIV infections in the US among men who have had sex with men (MSM) declined in the 1980s and 1990s but increased by 11% from 2001 to 2005, and MSM still account for most new HIV infections.1 Men who have had sex with men since 1977 have an HIV prevalence 60 times higher than the general population, 800 times higher than first time blood donors, and 8000 times higher than repeat blood donors.2

The approach to minimising infections in the US all-volunteer blood supply is two pronged—the donor questionnaire and laboratory testing. Testing for HIV includes antibody testing as well as molecular methods (nucleic acid amplification testing).