Based on its review of the limited information provided, the committee has a few overarching concerns. First, it appears that the contractor has not yet: been responsive to the committee’s recommendation that qualitative analyses addressing the three questions3 raised in our 2008 letter report be prepared first. Quantitative analysis should then be used to supplement the qualitative approach for the pathogens and release scenarios for which there appear to be potentially significant risk and where there are sufficient data to support the analyses. The committee has a related concern about the inputs to the modeling, most importantly the fact that a modified Delphi process was used to gather expert opinions that were then used as a substitute for actual data for modeling. This approach would not have been necessary if the committee’s recommendation that qualitative assessments be developed first had been followed. The committee also reiterates the need to include actual data in the models when they are available, for example, data on the speed of secondary transmission of SARS based on published results. Again, the models used must also be transparent, couched in the context of the risk assessment, and include attendant uncertainties.

While the committee commends NIH, Tetra Tech, and its subcontractors for carrying out some illustrative quantitative risk calculations, much work still needs to be done to adequately assess and communicate the risks associated with the NEIDL. Our report offers additional specific comments on the uncertainty analyses used in the modeling; the need to document assumptions; other issues concerning modeling; the need for case studies; and identification of vulnerable and susceptible populations.

This report reflects the consensus of the committee and has been reviewed in accordance with standard NRC procedures. The work was supported by Frances Sharples, Director of the NRC’s Board on Life Sciences, Panola Golson of the Board on Environmental Studies and Toxicology, and Kathi Hanna, our professional science writer.

The committee thanks NIH for seeking its input as it works to develop resources for advancing the national capacity to protect and improve health. The committee hopes that its suggestions will be useful in this regard.


John F. Ahearne, Chair

Committee on Continuing Assistance to the National Institutes of Health on Preparation of Additional Risk Assessments for the Boston University NEIDL


Risk triplet, as per S. Kaplan and B.J. Garrick. (1981). On the quantitative definition of risk. Risk Analyses 1 (1):11-27.

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