Why should men wait 4 months after sexual contact with a man to give blood?

Clarity of the subject

Belgian Red Cross-Flanders is a blood establishment recognized by law. Our main mission in this area is to provide sufficient and safe blood for patients. In doing so, we must take into account an important safety risk, namely that infectious diseases can be transmitted through blood transfusion. At the end of the 20th century, many people were infected with hepatitis C and HIV because little was known about these infections. We knew for some time that syphilis and hepatitis B were transmissible through blood and tested systematically. These tests were expanded to include hepatitis C and HIV in the early 21st century.

The current generation of sensitive tests provide a high degree of safety. Nevertheless, shortly after an infection, there always remains a window period in which an incipient infection cannot yet be detected by a test. This while the pathogen can already be transmitted through blood and thus make the recipient sick. For other suspected and also proven blood-borne infections such as hepatitis A and E, the Belgian government does not provide funding for testing and Belgian Red Cross-Flanders does not test for these.

In addition to the systematic testing of every donation, there are 2 other pillars that help us ensure a particularly high degree of safety of our blood products.

• The application of pathogen reduction techniques: Pathogen reduction involves treating blood products so that any bacteria and viruses present can no longer multiply. Unfortunately, these techniques are not equally effective toward all pathogens. In addition, they are currently applied only to plasma and platelets and not to the red blood cells administered during a conventional blood transfusion.
• Donor selection: Through the medical questionnaire and donor selection, health factors and situations that may pose a risk to the donor himself and/or to the recipient of his blood products during a donation are probed. Many of the questions aim to identify risk situations where blood-borne infections can be contracted such as travel, surgical procedures, piercing or tattooing,... and also sexual behavior. Donor selection is the main form of protection against recently contracted HIV/HBV/HCV/syphilis infections where tests may initially still show false negatives and against other blood-borne infections not (yet) tested for. After such risk situations, donors will be delayed for some time until we know that the tests are reliable or until we know that the period that a person can be infectious has passed. These risk situations and the corresponding deferral periods have been determined based on scientific data and, to a large extent, are also established by law.  

In 2017, the government set a legal 12-month deferral period for all persons who have had a sexual contact that poses an increased risk of contracting HIV and other blood-borne infections. Specifically, this includes persons with multiple sex partners, persons who have/were paid for sex and persons with a partner at risk for contracting HIV (for example, men who have sex with men or persons with a partner recently from an area with a higher prevalence for HIV). That relaxation was then also supported by research conducted by Belgian Red Cross-Flanders. A recent systematic review confirms the safety of a 12-month deferral period(Schroyens N et al. Men who have sex with men and risk for transfusion-transmissible infections in blood donors in Western countries: A systematic review update. Vox Sang. 2023.)

Specifically for men who have sex with men (MSM)

Men who have sex with men are a population group in Western countries in whom HIV is much more frequent than in the general population. 6 to 10% of men who have sex with men are thought to be affected by HIV. Also among MSM in monogamous relationships, the risk of undiagnosed HIV infection is significantly higher (55x) than among men in heterosexual relationships, even with a new partner.

We also see that the use of the HIV prevention pill (PrEP) is increasing in Belgium, with more than 95% of starters reporting MSM contacts. PrEP may cause tests for HIV to show delayed or no positive signs. At the same time, PrEP users may be under the false belief that their blood is safe.

But undetectable=untransmissible as with sex contacts, does not apply to blood transfusion. Here an undetectable low viral load can lead to infection of the patient anyway.

In addition to HIV, other sexually transmitted diseases (syphilis, gonorrhea, genital Herpes, Chlamydia) are more frequent among MSM. Sciensano also names men who have sex with men as a risk group for HAV, HEV, HBV and HCV. The outbreaks of COVID-19 and monkeypox have shown that we must always be vigilant for new or re-emerging pathogens where possible blood transmissibility is not yet known or not yet ruled out. Recently, the spread of monkeypox virus appeared to occur almost exclusively in MSM.

The new legislation

Even though the recent systematic review shows that there is too little evidence at present to conclude that a 4-month deferral period provides as high a degree of safety as a 12-month deferral period(Schroyens N et al. Men who have sex with men and risk for transfusion-transmissible infections in blood donors in Western countries: A systematic review update. Vox Sang. 2023.), yet in June 2022 the House of Representatives decided - for political-social reasons - to implement a more lenient policy for the group of MSM than for other high-risk groups. They chose to lower the deferral period from 12 to 4 months after the last sexual contact.

For other persons who had a sexual contact with increased risk, a 12-month deferral period remains provided in the legislation. As a blood establishment recognized by the law, we follow the legislation and implemented the relaxation of the deferral period after MSM from 12 months to 4 months on July 1, 2023.

We are well aware that in the meantime in quite a few countries the relaxation goes even further and where there is no more respite after MSM within a permanent homosexual relationship. In this, each country has its own legislation which, apart from scientific findings, is also based on political choices. And within each country, government funding helps determine the testing policy as well as the modalities within which collections can be organized. Based on models, the governments of these countries estimate that the additional risk they take - which is borne by the patient - is acceptable. In countries where individual risk assessments have been used for some time, such as Spain and Italy, we see that infections among donors are more frequent. Currently, there are certainly no data or studies available that show that a thorough questioning can adequately identify and reduce the higher risk among MSM.