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Topic # 2 Assessment for Potential Risk of Exposure to the vCJD Agent in Plasma Products. TSE Advisory Committee February 8, 2005 Dorothy Scott, M.D. LPD/DH/OBRR/CBER/FDA. Issue.
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Topic # 2Assessment for Potential Risk of Exposure to the vCJD Agent in Plasma Products TSE Advisory Committee February 8, 2005 Dorothy Scott, M.D. LPD/DH/OBRR/CBER/FDA
Issue • FDA seeks Committee advice on the design and input parameters of a risk assessment model for potential vCJD exposures from products made with U.S. plasma. • Rationale for vCJD risk assessments for plasma derivatives in the U.S.
Issue • U.S. risk assessment model for products made from U.S. plasma • Data and assumptions • Uncertainties, use of ranges and distributions • Sensitivity analysis
Rationale for Risk Assessment • Transfusion transmission of vCJD reported in the U.K. (12/2003 and 7/2004) • NO cases to date in any plasma derivative recipients • New information on vCJD prevalence and actual transmission by blood allows refinement of risk evaluations • Risk estimates provide a basis for reexamining adequacy of current measures to protect blood and plasma derived products • The risk model provides a framework to update risk estimates, and contributes to public health decisions
Risk Assessment CAN Provide • A framework for more precise risk assessments in the future • Ranking of product classes that may have greater or lesser margins of safety • Estimation of likely, best-case, and worst-case risk of exposure to vCJD via products • Estimation of the need for additional risk reduction measures • Estimation of levels of TSE clearance in manufacturing that are likely to be meaningful • Risk communication to the public
Risk Assessment CANNOT Provide • A precise prediction of risk, because of uncertainties such as • Actual prevalence of vCJD agent in blood/plasma donors • Timing of presence of infectivity in blood of infected individuals during the incubation period • Amount of infectivity in human blood • Effectiveness of blood donor deferrals • vCJD agent clearance in manufacturing processes • Effects of cumulative low-level exposure to vCJD agent • Susceptibility of recipients to infection if exposed to vCJD agent
vCJD Risk Assessments for Blood and Plasma Products • Det Norske Veritas (commissioned by U.K. Health Authorities), at http://www.dnv.com/consulting/news_consulting/RiskofInfectionfromvariantCJDinBlood.aspsite • France (AFSSAPS), at www.agmed.sante.gouv.fr/ang/pdf/mcj02.pdf • and www.agmed.sante.gouv.fr/ang/pdf/mcj04.pdf
Questions to the TSEAC Please comment with regard to: • The U.S. risk assessment model per se; and • Any additional information that is needed to improve risk estimates for the various plasma derivatives