A woman is given a flu shot by at the medical offices of Yaffe Ruden & Associates in New York on Jan. 10, 2013. The Centers for Disease Control and Prevention has said that this year's flu season is expected to be one of the worst the country has seen in 10 years. - 

If you’re out sick today with flu, be assured you have company. The CDC tomorrow release  its latest flu count numbers and the agency’s expecting a big spike. The flu came early and it came on strong this year and that could weaken an economy that’s not in the best of health as it is.

The Centers for Disease Control says your typical flu season -- and this may not be -- costs employers over  $10 billion, just in direct doctor and hospital visits alone.

The $10 billion doesn’t even count lost productivity. Economists say an exceptionally strong flu season could undercut an already struggling U.S. economy and could hurt this quarter’s GDP numbers.

Sick employees who drag themselves into the office could make it worse.

“A lot of people don’t just come into work when they’re sick because that’s kind of the work ethic,” says John Challenger at the outplacement firm Challenger, Gray and Christmas. “It’s because they can’t afford to and they can’t take the risk of losing their jobs.”

Key O’Keefe, a partner at a small CPA firm in Melbourne, Fla., says she’s telling her employees to stay at home of they are sick. “Then they can come in and work as many hours as they’re capable of working.” That could be a lot, given that O’Keefe’s busy season, tax time, is fast-approaching.

Aside from businesses, school districts worry about flu season as well. Districts in states like California, New York and Texas, where state funding depends on daily attendance numbers rather than enrollment, can lose substantial support. In Austin, Texas, for example, the district forfeits $45 a day in state funding when a student misses class.

Of course, makers of vaccines, cold medicines and drugstores can make up for some of flu season’s lost revenues. Walgreens reports that it’s already given out 5.7 million flu shots so far this season as compared to 5.3 million this time last year.

Follow Sarah Gardner at @RadioGardner