By Dr. George Huang

We're about to see a huge epidemic. As many as one in five people will get sick. U.S. and global corporations will lose billions of dollars.

Half a million people will die.

Every year around this time, the influenza virus, commonly known as the flu, infects 10%-20% of the world population. The World Health Organization estimates as many as 500,000 people die annually from influenza-associated complications.

While the plain vanilla seasonal flu causes substantial suffering, it rarely hits the mainstream press. And no one really takes it too seriously.

A flu vaccine offers full protection two-thirds of the time. Yet, in the U.S., only a third of the population opts to get one. So the flu market, while profitable, doesn't usually conjure much investor excitement.

This year, the threat of a swine flu pandemic changed all that. And it's going to be a windfall for a few select drugmakers...

To demonstrate their worth to constituents, government bureaucrats worldwide are scrambling to arrange mass vaccinations. Greece, the Netherlands, Canada, and Israel, for example, have ordered enough swine flu vaccine to inoculate their entire populations.

But the seasonal flu vaccine will not protect you from the swine flu. So a minimum of two shots – one for the seasonal flu and one for the swine flu – will be necessary for full protection in the upcoming flu season.

Such generosity with tax-payer money will result in massive sales increases for manufacturers of flu vaccines... Big vaccine makers, like GlaxoSmithKline (GSK), could generate additional revenue of $1 billion to $2 billion this year. But the increase won't even be a blip in its $40 billion budget.

Instead, we should target companies where flu vaccine sales make up a large portion of total revenue. My favorite play is Dutch biotech company Crucell (CRXL).

Crucell, the seventh-largest vaccine maker in the world, sells the flu vaccine Inflexal. Mild flu seasons over the last two years have made it difficult for Crucell to grow its flu vaccine franchise. But if advance orders from competing firms are any indication, Crucell could increase its seasonal flu vaccine sales by at least 50% this year. That could translate to an extra, unexpected $40 million in revenue. For a firm with about $400 million in sales, that's no chump change.

I recommended Crucell to my FDA Report subscribers early this year. We are up 20% already on the trade. But it's not too late to get in.

With a market cap of only $1.4 billion, Crucell has plenty of room to run. I expect shares to jump from about $22 to above $25 as the flu season picks up. That's good for a quick 20% return in a few weeks.