A pilot study that could lead to changes in federal rules prohibiting sexually active men who have sex with men from donating blood is seeking 200 more participants in the Bay Area before July.

The study is called the ADVANCE Study, which stands for Assessing Donor Variability And New Concepts in Eligibility. The study comes as the American Red Cross declared a blood supply shortage January 11 and as 22 U.S.

senators sent a letter to Xavier Becerra, the secretary of the Department of Health and Human Services, and Dr. Janet Woodcock, the acting commissioner of the Food and Drug Administration, asking them to scrap decades of restrictions on gay and bisexual men donating blood.