Bethesda, Md—In December 1993, concerned about the increasing numbers of animals being diagnosed as having bovine spongiform encephalopathy (BSE or "mad cow disease") in countries abroad, the US Food and Drug Administration (FDA) recommended that US manufacturers of medicinal and biological products not use materials from animals in countries reporting BSE. These materials include serum, bone, and nervous system tissue. The agency's position was that the agent of BSE could be present in these materials and transmitted to patients, where it might cause Creutzfeld-Jakob disease (CJD).
Marwick C. FDA Calls Bovine-Based Vaccines Currently Safe. JAMA. 2000;284(10):1231-1232. doi:10.1001/jama.284.10.1231-JMN0913-3-1