WASHINGTON -- The Food and Drug Administration is pondering a new, stricter test to screen blood donations for the AIDS virus but will likely decide against it because it costs too much.
The test, scientists say, would prevent up to 20 transfusions of HIV-infected blood a year but would come at a cost of at least $24 million.
"While I sympathize, I don't think that's an issue," said Louis M. Katz, chairman of an FDA advisory panel that ruled against the test after a controversial debate. "It's inconceivable in 1995 that we would consider a test that would cost so much."
The FDA is not required to adopt the advisory panel's recommendations, but it usually does so. Although officials would not say when the agency would make a decision, the process often takes months.
The panel's decision to side with the bottom line came after conflicting testimony from blood banks, doctors and people with acquired immune deficiency syndrome who were infected with the human immunodeficiency virus by contaminated blood transfusions.
The Red Cross, the country's premier collector of blood, strongly advised that the panel approve the test. The Council of Community Blood Centers, which collects about 40 percent of the nation's donated blood, advised against it, saying the same result could be achieved by screening high-risk donors.
The test would have improved the ability to spot rare instances of infected blood. Right now, mandatory tests of all blood donations look for signs of antibodies, the cells that immune systems of HIV-infected people produce to fight the virus.
The problem is that the antibodies are not produced at the moment of infection. The body's immune system takes three to six weeks to figure out it is under attack and mount a response recognizable by the test.
If an infected person donates blood in the interim, tests will show the blood to be uninfected. Transfusing such blood results almost certainly in HIV infection for the patient receiving it.
Such "window" transfusions of infected blood are rare.
"About 19 to 27 of the 12 million units of blood collected each year would be in the infected window period," said Eve Lackritz, a scientist at the Centers for Disease Control and Prevention in Atlanta.
The new test would not close the window but shorten it about a week. After the FDA panel vote, scientists and representatives from the blood organizations stressed that the nation's blood supplies were still largely safe. Red Cross spokesman Richard Davey said the risk of getting an infected blood transfusion in the window period was 1 in 420,000.
The scientists stressed that there would always be a small risk, and Mr. Davey said there is a 14-day window that can never be closed by any test.