Sanofi-aventis (NYSE:SNY) booked a solid quarter, even raised earnings estimates, but investors are thinking a little more long-term and there isn't much -- not even the swine flu -- that can help sanofi's long-term revenue trajectory.

CEO Chris Viehbacher was pretty clear, "At the moment, we don’t think the H1N1 sales will necessarily be that significant this year." Production is likely to be the limiting factor, rather than demand, but, even if sanofi could make more of the product, it would still be a minor part of sanofi's $40 billion or so in annual revenue. And besides, the production of the vaccine is hopefully a one-time thing. Once the pandemic is over, the corresponding revenue vanishes as well. Investors in GlaxoSmithKline (NYSE:GSK), Novartis (NYSE:NVS), Baxter International (NYSE:BAX), and others trying to make vaccines against the strain that causes swine flu should heed sanofi's warning.

Despite the strong quarter -- revenue was up 6.5% at constant currency and adjusted EPS were up 17.2% on the same basis -- sanofi still faces a major obstacle with generic competition looming for Lovenox, Eloxatin, and Plavix. Add in concern that its insulin product, Lantus, is possibly linked to cancer and you have a company that's going to have a difficult time growing earnings in the future, even if it's looking good now and might eventually get a small bump from the swine flu.

Much like Eli Lilly (NYSE:LLY), sanofi isn't getting any kick in its share price from raising earnings today, because investors can see through the facade. Until the patent cliff happens, investors are going to have to be happy collecting their substantial 4.4% dividend and hope Viehbacher can make some smart acquisitions or changes that help make the fall from the cliff as soft as possible.

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Fool contributor Brian Orelli, Ph.D., doesn't own shares of any company mentioned in this article. The Fool has a disclosure policy.