Many countries have laws that prohibit donations of blood or tissue for organ transplants from men who have sex with men (MSM), a classification of men who engage (or have engaged in the past) in sex with other men, regardless of whether they identify themselves as bisexual, gay or otherwise. Restrictions on donors are sometimes called "deferrals", since blood donors who are found ineligible may be found eligible at a later date. However, many deferrals are indefinite meaning that donation may not be accepted at any point in the future, thus constituting a de facto ban.
Restrictions vary from country to country, and in some countries practice of protected sex or periods of abstinence are not considered. The restrictions affect these men and, in some cases, any female sex partners. They do not otherwise affect other women, including women who have sex with women. The United States Food & Drug Administration (FDA) asserts that the one year deferral window is "supported by the best available scientific evidence". However, in Canada, the deferral period has been decreased to 3 months, as of June 2019. This change was also based on scientific evidence.
Many LGBT organizations view the restrictions on donation as based on homophobia and not based on valid medical concern since donations are rigorously tested to rule out donors that are infected with known viruses such as HIV, HPV, Hepatitis B, and Hepatitis C. They state the deferrals are based on stereotypes. Proponents of the lifetime restriction defend it because of the asserted risk of false negative test results and because the MSM population in developed countries tends to have a higher prevalence of HIV/AIDS infection. The UK government advisory committee, SABTO, stated in 2013 that "the risk of transfusion of HIV infected blood would increase if MSM were allowed to donate blood". In July 2017 however, the UK government reduced the one year deferral window to three months, to take effect in the following months, resulting from SABTO's updated conclusions that "new testing systems were accurate and donors were good at complying with the rules". Furthermore, NHS Blood and Transplant are in the process of investigating how possible it is for MSM, depending on degree of risk, to donate without even the three-month deferral. NHS has said that there is currently a limited amount of data on effective ways of conducting such risk assessments, and that the initial steps of scoping, evidence gathering and testing will potentially take up to two years to complete.
Advocates for change to MSM prohibitions point out that screening of donors should focus on sexual behavior as well as safe sex practices since many MSM may always have protected sex, be monogamous, or be in other low risk categories. Some groups in favor of lifting the restrictions support a waiting period after the blood is donated when the donor is considered to have had behavior considered higher risk, and before it is used, to match the blood bank's window of testing methods. While HIV is reliably detected in 10 to 14 days with RNA testing, older testing methods provide accuracy for only up to 98% of positive cases after three months.
Since 1982, the risk for HIV infection transmitted via transfusion has been almost eliminated by the use of questionnaires to exclude donors at higher risk for HIV infection and performing screening tests with highly sensitive equipment to identify infected blood donations. According to the 2015 surveillance report by Canadian Blood Services, the risk of HIV transfusion-transmitted infection was fairly low: in 1 in 21.4million donations. Contaminated blood put haemophiliacs at massive risk and severe mortality, increasing the risk of common surgical procedures. People who contracted HIV from a contaminated blood transfusion include Isaac Asimov, who received a blood transfusion following a cardiac surgery.
In many developed countries HIV is more prevalent among men who have sex with men (MSM) than among the general population.
In the United States the population most affected by HIV includes gay, bisexual, and other MSM. Of the 38,739 new HIV diagnoses in the US and dependent areas in 2017, 70% consisted of adult and adolescent gay and bisexual men. Although approximately 492,000 sexually active gay and bisexual men are at high risk for HIV, there are more tools to prevent HIV than ever before.