“The 2009 H1N1 virus, also known as swine flu, is the predominant virus this season,” says Keri Peterson, MD, of the American College of Physicians and the American Medical Association. And while many workers place their jobs as a top priority, they should not do so at the expense of their health—and the health of their colleagues. “As always, vaccination is the first step in flu prevention, but it’s also important for everyone to help prevent the spread of the flu virus.” Fever, severe coughing, and sneezing are all signs to stay home, she says. (Learn the difference between a cold and the flu.) Every workplace is different, but your supervisor should understand the adverse effects of coming in when you’re under the weather. If you have an unsympathetic boss, consider reminding him or her that you staying home really is what’s best for the company—after all, if your bug spreads around the office it won’t just tamp down your productivity, but your coworkers’ too.  More from Prevention: Bounce Back From A Cold Or Flu—Fast