In order to reduce the risk of blood transfusion-associated HIV transmission during the window period between exposure and detectability among donors, most countries either permanently or temporarily defer gay, bisexual, and other men who have sex with men (MSM). Both Canada and the U.S. defer MSM for three months since the last sexual contact. To inform blood donation selection criteria in Canada, researchers examined factors associated with HIV seroconversion among gay, bisexual and other MSM in three major cities. Between 2017 and 2021, 2008 HIV-negative gay, bisexual and other MSM (aged >16) were recruited using respondent-driving sampling and completed a questionnaire on their drug and sexual activity during the past six months. Participants were also screened for sexually transmitted infections. Participants completed follow-up questionnaires and screenings every 6 to 12 months. During the study, 31 participants seroconverted for an HIV incidence rate 0.4 cases per 100 years (95% C.I., 0.3 to 0.6). Risk factors for recent HIV seroconversion were age <30 years, six or more anal sex partners, and use of crystal methamphetamine during sex. Based on applying combined selection criteria, three screening questions regarding drug injection, new anal sex partners, and total number of anal sex partners would identify all participants who seroconverted (100% sensitivity and 100% negative predictive value). Individualized behavior based-donor eligibility criteria may reduce the number of MSM deferred by one-third.
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