Screening for antibody to cytomegalovirus (CMV) is performed on products intended for immunocompromised recipients such as patients undergoing chemotherapy for leukemia or cancer, transplant patients, and low birth-weight infants.

In early 1999, the American Red Cross (and other blood collecting organizations) began studying a new test for HIV and hepatitis C called nucleic acid amplification (NAT), designed to detect portions of the actual virus itself. Based on preliminary data, it is hoped this test will further shorten the "window period" for these viruses, resulting in a significant improvement in blood safety.