OVER 112m blood donations are collected around the world annually. But there will never be enough blood. Fully 90% of eligible donors do not donate and because blood has a short shelf life, hospitals and patients are highly dependent on regular donations. In spite of the need, some groups are not allowed to give blood. Hospitals clearly don’t want blood that could contain dangerous diseases, like HIV or viral hepatitis. Intravenous drug users and sex workers are often crossed off the list. But some restrictions are more contentious. Men who have sex with men are entirely prohibited from donating blood in countries such as Austria, Denmark and Greece. Elsewhere men must abstain from gay sex from between three months to five years before donating. Why are gay or bisexual men still barred from donating blood?

Such policies stem from the AIDS epidemic in the 1980s. At the time, tests to check blood for viruses were not reliable. Contaminated blood supplies caused over 20,000 HIV infections in America alone. As a precaution, governments worldwide prohibited high-risk groups from donating blood. This included men who had sex with men, as well as their female sexual partners. There were no exceptions for men who were in monogamous relationships, stayed protected or had not had sex with a man for years. But what began as an emergency measure soon became a deeply rooted norm.

While it is true that gay men are at higher risk than the general population of contracting a blood-borne virus or infection, there is now no scientific justification for a blanket ban on blood donations. LGBT organisations argue that such measures are homophobic and discriminatory. The risk of blood contamination is extremely low as new technologies allow donations to be rigorously tested before being used in transfusions. The newest generation of tests can spot HIV within a month of infection. What is more, heterosexuals who engage in risky sexual behaviour do not face the same level of scrutiny. Blanket bans imply that all gay and bisexual men are as high-risk as intravenous drug users. Nor are such bans very efficient. In Britain, nearly 11% of men who had had sex with men reported donating blood in spite of restrictions.

Many countries are now abandoning indefinite bans. Many have opted instead for temporary deferrals. A ban was in place in America until 2015. Now men there are required to abstain from gay sex for a year. Britain dropped its ban in 2011, and last year reduced its 12-month quarantine to three months.  Experts in the British department of health found that this was a long enough window for all viruses to be caught in tests. In May, Taiwan will allow gay men to donate blood if they have not had sex with a man for five years. Other states, like Mexico, Spain and South Africa, have no special restrictions for sexual minorities. This is the approach favoured by many LGBT groups, who lobby for risk assessments to focus on individuals not groups. A UCLA study from 2014 estimates that lifting the restrictions on blood donations for sexually active gay men in America would increase the country’s blood supply by 2-4%. As the red blood cells, plasma and platelets of each donation can be used separately, that could amount to millions of saved lives.