(Posted By: Josi Creek)
January 22, 2010

NEW YORK (Dow Jones)--Biogen Idec Inc. (BIIB) will communicate with doctors once a month on the occurrence of new cases of a rare brain infection in patients using its multiple sclerosis treatment Tysabri, as the biotech strives to find the right balance in keeping the medical and financial communities updated on that important number.

The situation is closely watched because Tysabri, a highly effective treatment sold with Elan Corp. (ELN), was previously pulled from the market because of its association with progressive multifocal leukoencephalopathy, or PML, a debilitating and often fatal condition. The infection rate has hurt the sales growth of the drug, which is key to Biogen's future and is Elan's biggest seller.

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