Many countries have laws, regulations, or recommendations that effectively prohibit<unk> s of blood or tissue for organ and corneal transplants from men who have<unk>  with men (MSM), a classification of males who engage or have engaged in<unk>  with other males, irrespective of their<unk> ual activities with same-sex partners and of whether they identify themselves as bisexual or gay. Temporary<unk>  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<unk>  are not accepted at any point in the future, constituting a de facto ban. Even men who have monogamous relations with their same-sex partner are found ineligible.<unk>  vary from country to country, and in some countries practice of protected<unk>  or periods of abstinence are not considered. The<unk>  affect these men and, in some cases, any female<unk>  partners. They do not otherwise affect other women, including women who have<unk>  with women. With regard to blood<unk> , the United States Food & Drug Administration (FDA) enforces a three-month deferral period for MSM and women who have<unk>  with MSM. In Canada, the deferral period for MSM blood donors was decreased to 3 months in June 2019. Meanwhile, for tissues such as corneas, the MSM deferral period is five years in the United States and 12 months in Canada. Many LGBT organizations view the<unk>  on<unk>  as based on homophobia and not based on valid medical concern since<unk> s are rigorously tested to rule out donors that are infected with known viruses such as HIV, hepatitis B, and hepatitis C. They state the deferrals are based on stereotypes. Proponents of the lifetime<unk> 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<unk> ual behavior as well as safe<unk>  practices since many MSM may always have protected<unk> , be monogamous, or be in other low risk categories. Some groups in favor of lifting the<unk>  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<unk> s. According to the 2015 surveillance report by Canadian Blood Services, the risk of HIV transfusion-transmitted infection was fairly low: in 1 in 21.4 million<unk> s. 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.
Blood donation restrictions on men who have sex with men
Vaccination requirements for international travel
Young blood transfusion
Credé's prophylaxis
Contaminated haemophilia blood products
Jehovah's Witnesses and blood transfusions
HIV-tainted blood scandal 
Probiotics in children