As the flu season starts, it appears that Chiron ( CHIR) will be slow in getting its vaccine to market. How slow and how much product will be affected are still subjects of conjecture. The company is awaiting approval from the Food and Drug Administration to clear its Fluvirin vaccine, even as the agency has granted the go-ahead for three competitors to begin shipping some batches of their flu vaccines. Manufacturing problems at its British plant caused Chiron to cancel its flu vaccine in the U.S. last year, and regulatory reviews have pushed back the deadline for Chiron's plans to sell a reduced amount of vaccine for the 2005-2006 season. "Chiron is likely to make it back to the market this year, but it is likely to ship volume at the low end of their previous guidance range of 18 million to 26 million doses," says Geoffrey Porges of Sanford Bernstein in a Monday research report. That range represents a reduction from 25 million to 30 million doses that Chiron had predicted earlier this year and a big cut from the 48 million to 50 million doses that U.S. public health agencies had been expecting for the 2004-2005 flu season. Porges interviewed distributors who told him that Chiron informed them it will provide only half the amount they had expected for October. Chiron also gave them the option to cancel their November shipments, he says. Porges says this "suggests a supply shortfall relative to Chiron's original expectations, rather than a contractual obligation or courtesy." The analyst, who has a market-perform rating on the stock, expects distributors to ask for at least part of their November allotment, adding that Chiron's flu vaccine sales will depend on the severity of the season.