Reply to “Studies on Influenza Virus Transmission between Ferrets: the Public Health Risks Revisited”

Lipsitch, Marc; Inglesby, Thomas V.

(ii) The claim of lack of transmission in humans is a sharp departure from earlier claims. Fouchier initiated public discussion of these studies by claiming he had created "probably one of the most dangerous viruses you can make" (29) . Current denials that this is possible seem to be designed to reduce perceived risk from the experiments rather than to describe new scientific data or understanding. Paul Keim, the Chair of the National Science Advisory Board on Biosecurity who reviewed the original submission of the H5N1 paper, stated, "I can't think of another pathogenic organism that is as scary as this one" (29) . The reaction of another member of the NSABB, Michael Imperiale, was as follows: "[Imperiale] also says it was news to him that the mutated virus did not spread between ferrets via the aerosol route as readily as seasonal strains, as Fouchier showed at the ASM meeting. 'That really didn't come across to me in the paper,' he says. 'I didn't see that kind of comparison.'" (30) . Without understanding why this change in interpretation has occurred, it is difficult to incorporate into a risk analysis a speculation that ferret adaptation reduces human adaptation, as Fouchier argues in his paper. Moreover, whether or not this occurred in the particular experiment involving H5N1 in the Fouchier lab, it cannot be assumed to be a reliable outcome of future studies.