President Obama called on Americans on Tuesday to take common-sense steps to help contain the expected impact of swine flu, including staying home from work when they are sick, frequently washing their hands, and covering their sneezes with a sleeve instead of a hand. Obama told reporters in the Rose Garden that the federal government is taking a coordinated approach to fighting the expected outbreak, including ramping up what he says will be a 'voluntary but strongly recommended' H1N1 flu vaccination program. The president has received regular briefings on the flu pandemic, including one Tuesday from several Cabinet members and other top officials. He has asked officials to 'spare no effort in addressing this national security challenge,' according to the White House. The H1N1 virus brushed the United States this spring, and health officials expect a stronger impact this fall and winter. Half of Americans could be infected with the virus and as many as 90,000 could die -- more than double the typical death toll from seasonal flu -- according to a planning scenario issued late last month by the President's Council of Advisers on Science and Technology. The medical community could be overwhelmed by the outbreak, which could lead to as many as 1.8 million patients being hospitalized in the United States, according to the planning scenario. Obama said steady progress is being made on developing a swine flu vaccine and that a huge inoculation program 'will begin soon.' 'I don't want anybody to be alarmed,' he said about the scenarios sketched about the possible impact of the flu. 'But I do want everybody to prepared.' 