Customs agents have stopped and cleared 41 people with flulike symptoms at U.S. borders and are awaiting test results on eight more.
Homeland Security Secretary Janet Napolitano cited the numbers as she explained why no tightening of the U.S. border was needed.
She said the novel swine flu virus already has spread into this country and others, and it's too late for border closures to contain.
At the border, none of the 49 people stopped so far was detained for more than a few hours while health officials checked them. She didn't say where along the border people were stopped. Because symptoms may arise later, officials are handing out cards explaining the flulike symptoms to arriving travelers.