The secretaries of commerce, education and homeland security offered guidance to businesses on how to prevent the spread of the H1N1 virus and how to prepare for a major outbreak. They stressed the importance of allowing employees who exhibit flu symptoms to go home and stay home until at least 24 hours after their fevers subside. They also said that businesses should consider eliminating policies requiring a doctor’s note to justify a sick day and that employers should be prepared to operate with fewer people. In the U.S., 7,511 people have been hospitalized and 477 have died of swine flu, according to Aug. 13 figures from the CDC. Still, as the H1N1 virus swept across the world, many Americans who were infected had only mild symptoms and recovered without incident, while countries such as Mexico suffered a high mortality rate for reasons that aren’t clear. Kids six months to nine years old who’ve never been immunized against seasonal flu require two doses of that vaccine while those who’ve been previously immunized only need one. Clinical trial results from the H1N1 flu vaccine aren’t in yet, so it’s not clear whether one or two doses will be required.