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This article discusses FDA's current thinking on B19 NAT testing for plasma fractionation, including limits on B19 DNA, testing procedures, and the impact on AHF products.
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B19 Testing of Plasma for Fractionation:Current ThinkingMei-ying W Yu, PhDDivision of HematologyCBER/FDASoGAT XVIIMay 26-27, 2004
FDA’s Current Thinking on B19 NAT(Policy Pending) Plasma Fractionators: • Limit B19 DNA to <104 geq/mL, in manufacturing pools, assuming • Anti-B19 in large pools complexes/neutralizes virus • Manufacturing procedures clear the virus • High-titer B19 reactive units, 106 geq/mL, should not be used for manufacturing pools of plasma derivatives, to ensure that the FDA’s proposed limit can be met. • High-titer B19 minipool NAT screening is an in-process test • Reactive minipools are resolved to single donations • Results are used to reject reactive donations
FDA’s Current Thinking on B19 NAT(Policy Pending) Whole Blood: • Reduce the risks to transfusion recipients by withholding high-titer positive units (106 geq/mL) of Whole Blood and its components from use • The overall value of screening WB donors has not been established • Testing for B19 has not been widely implemented • Temporarily defer apheresis donors (used to make transfusion components) but not Whole Blood or Source Plasma donors • Potential medical benefits to close contacts of B19 infected donors warrant notification of high-titer donors, but only if donor notification can be completed within several weeks of donation
Parvovirus B19 NATCurrent Status Source Plasma Fractionators • Most implement voluntarily B19 minipool NAT screening as an in-process test • Reviewed by the FDA as an analytical procedure • Results are used to reject reactive single donations but not donors (due to resolution time and 60-day inventory hold) • Most implement manufacturing pool testing • 105IU/mL (PPTA) or <104 IU/mL of B19 DNA
B19 DNA in Antihemophilic Factor (AHF)1993-1998 Log (geq/mL) Product # Pos/# Lots (%) Max. Mean A 9/13 (69) 4 2.4 B 22/25 (88) 4 3.0 C 14/15 (93) 5 3.4 D 16/16 (100) 6 3.9 E 16/25 (64) 6 3.1 F 24/43 (56) 3 1.7 Total 101/137 (74)
B19 DNA in Antihemophilic Factor (AHF)2002-2003 Log (geq/mL) Product # Pos/# Lots (%) Max Mean A 6/12 (50) 3 1.7 B 1/ 5 (20) 1 1.1 C 6/ 7 (86) 4 3.0 D 4/ 5 (80) 2 1.4 E 5/15 (30) 1 0.9 F 3/16 (19) <1 0.5 Total 25/60 (42) [19/53 (36)]
Effect of B19 NAT Screening on AHFInterim Data Summary • B19 NAT screening effectively lowered B19 DNA levels in most AHF products prepared from Source Plasma. However, some lots still had 103 geq/mL(IU/mL) ofB19 DNA. • Prevalence and levels of B19 DNA in AHF products derived from recovered plasma were high since B19 NAT screening has not been implemented. • It remains to be determined whether Factor VIII products containing low residual levels of B19 still may transmit the infection to susceptible individuals, and whether the risk is reduced compared with products made from unscreened plasma.