Both the FDA and its joint advisory committee concluded that the risk for vCJD posed by vaccines is theoretical and remote. Studies of the BSE agent have shown that infectivity depends on nature of material used, how much is used and the route of administration.

Other factors, such as the country of origin of the cattle used to supply the manufacturing material, also have to be factored into any risk estimate. Both the European Community and the US Pharmaceutical industry have presented risk assessment calculations which attempt to account for all these factors.

In 1999, the Council on Scientific Affairs (CSA) of American Medical Association considered the risk of BSE to public health and determined that the current risk of transmission of BSE in the US is minimal, concluding that adequate guidelines exist to prevent high risk bovine materials from contaminating products intended for human use.

The report from the CSA did not address the possibility that regulated industry might not follow all of the recommendations made by the FDA. However, both FDA and the joint advisory committee meeting have considered the risks posed by bovine material in vaccines and concluded that any risk is remote and theoretical.