A federal advisory committee on Tuesday unanimously approved over-the-counter sale of a rapid HIV test, acknowledging the need for new tools against an epidemic that is driven largely by people who don’t know their status and infect others.

If the Food and Drug Administration agrees with its advisers, the oral swab screening device made by OraSure Technologies Inc. of Bethlehem, Pa., would become the first infectious disease test approved for home use.

The panel overcame considerable unknowns and concerns that the test cannot pick up newly acquired infections.

“I still can’t get past the quarter-million people who don’t get tested,” said member Steven W. Pipe, a pediatrics and communicable diseases specialist at the University of Michigan.

An estimated 240,000 Americans are unaware that they are HIV positive, and are responsible for 50 percent to 70 percent of the 50,000 new infections each year.

The test uses fluid from a swab of the gums. If a single horizontal line appears after 20 minutes, it has not detected antibodies to HIV. Two lines mean it is HIV positive, a preliminary finding that must be confirmed by a laboratory blood test.

“We believe we are at a deciding moment in the trajectory of the AIDS epidemic,” Phill Wilson, executive director of the Black AIDS Institute, told the panel, referring to treatments that dramatically reduce transmission of HIV, the virus that causes AIDS. “The key to that begins with getting them tested.”

The company has not disclosed a retail price or projected sales, although it estimated the entire market for rapid home HIV tests at $500 million retail. FDA staff projected that the test would be used by 2.8 million people in the first year. It would discover about 45,000 infections that otherwise would have remained unknown, and in turn, prevent HIV from spreading to 4,000 more people, the agency said.

But it also would result in several thousand false negatives, either because consumers didn’t use it properly or their infections were too new to trigger the immune system response that produces antibodies picked up by the test.

Much of Tuesday’s discussion among the advisory committee was about labeling and other ways to make clear to people at high risk of HIV that a negative test should be repeated three months later or confirmed with a laboratory blood test. Of particular concern was that people not use a negative result as a free pass to engage in risky sex.

The company has said that each test kit would include two booklets - one with detailed information about HIV and the other on the meaning of test results - in English and Spanish. It also would refer people to a 24-hour call center. In addition to helping people understand their test results, the bilingual staff would be trained as crisis counselors and could link callers to local counseling and a medical treatment.

In a teleconference with reporters after the advisory panel’s 17-0 vote, OraSure officials said they would immediately begin working with the FDA to address labeling issues.

“We are extremely pleased with the outcome of today’s meeting,” said Douglas A. Michels, president and CEO of the company, which has 270 employees.