HOW DEEP an incursion has human immunodeficiency virus (HIV) made into the population of the United States? Are 1.5 million (estimated) seropositive persons really infected now and likely sooner or later to come down with acquired immunodeficiency syndrome (AIDS)? Could the actual number be much lower—or much higher? The Centers for Disease Control (CDC), Atlanta, is trying to answer these tough questions. Next month, a study that may point the way toward getting part of the answer will begin in a medium-sized city in the mid-Atlantic states. Gary Noble, MD, the CDC's deputy director for AIDS, says the way is being carefully prepared for this initial pilot study, which aims to gather from 300 to 500 households information that will help determine the feasibility of conducting a full-scale National Household Seroprevalence Survey. Early Setback This blood sample and interview survey, planned to be an important part of the Comprehensive Family