(MONEY.CNN) — As flu season hits, a lot of people who should be home sick will instead be dragging themselves to work.

While some are likely just workaholics, others don’t have a choice: An estimated 41.7 million American workers can’t take sick days, according to the Bureau of Labor Statistics. That’s nearly a third of the nation’s employees, and a problem that raises health risks for everyone.

The nation’s current flu epidemic is more widespread in part because of the many sick people who can’t afford to stay home. A study published last year in the American Journal of Public Health estimates that an additional 5 million people became infected with flu symptoms in 2009 alone due to workplace policies, such as lack of paid sick leave.

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