Causality assessment of suspected virus transmission by human plasma products

Evaluation of Risk Minimisation Measures for Blood Components - Based on Reporting Rates of Transfusion-Transmitted Reactions (1997-2013)

BACKGROUND

To assess the impact of safety measures, we compared reporting rates of transfusion-related reactions before and after the implementation of six measures in 1999, 2004, 2006, 2008 and 2009.

METHODS

Reporting rates of transfusion-transmitted bacterial infection (TTBI), viral infection (TTVI) and immune-mediated transfusion-related acute lung injury (TRALI) were calculated on the basis of confirmed annual reports and distributed blood components.

RESULTS

The introduction of HCV NAT testing caused a significant reduction of HCV reporting rate from 1:0.6 to 1:83.16 million administered blood components (p < 0.0001), donor screening for antibodies to hepatitis B core antigen caused a reduction of HBV reporting rate from 1:2.90 to 1:10.70 million units (p = 0.0168). A significant reduction from 1:0.094 to 1:2.42 million fresh frozen plasma (FFP) units could also be achieved by risk minimisation TRALI measures (p < 0.0001). Implementation of pre-donation sampling did not result in a significant decrease in TTBI, whereas limitation of shelf life for platelet concentrate (PC) minimised the TTBI reporting rate from 1:0.088 to 1:0.19 million PC units (p = 0.041). For HIV NAT pool testing, no significant reduction in HIV transmission was found due to very low reporting rates (1:10 million versus 1:27 million blood components, p = 0.422).

CONCLUSION

On the basis of haemovigilance data, a significant benefit could be demonstrated for four of six implemented safety measures.

The German Haemovigilance System--reports of serious adverse transfusion reactions between 1997 and 2007

Data of the German Haemovigilance System were collected from 1997 to 2007 and assessed on the basis of pre-defined safety standards. Suspected cases of serious adverse reactions following transfusions reported to the Paul-Ehrlich-Institut were evaluated on the basis of national criteria, and the definitions of International Society of Blood Transfusion (ISBT) in compliance with defined causality criteria. The suspected cases were rated as confirmed and unconfirmed transfusion reactions. Assessment of causality took into consideration the clinical course of the adverse reaction and, if necessary, information about donation and manufacturing. Of the 5128 suspected serious adverse reactions, 1603 could be confirmed. Referring to the absolute figures, acute transfusion reactions (e.g. allergic reactions, hypotension and dyspnoea) were recorded most frequently, followed by transfusion-related acute lung injury (TRALI), haemolytic reactions, transfusion-related bacterial infections and virus infections. The majority of the 52 transfusion-related fatalities (14 each) were due to TRALI and acute transfusion reactions (mostly severe allergic reactions). Referred to the blood products administered, immune TRALI cases and TRALI-related fatal courses were most frequently reported after administration of fresh frozen plasma (FFP) (15/10(6) and 3.5/10(6) units, respectively), transfusion-related bacterial infections after administration of platelet concentrates (7/10(6) units), acute haemolytic transfusion reactions after administration of red blood cell concentrates (2.3/10(6)units) and acute transfusion reactions after administration of red blood cell or platelet concentrates (7.8/10(6) and 13/10(6) units, respectively). Despite the high safety standard required for blood products in Germany, there is still room for reducing the frequency of isolated cases of transfusion reactions by targeted action.

Experience of mandatory nucleic acid test (NAT) screening across all blood organizations in Germany: NAT yield versus breakthrough transmissions

BACKGROUND

Mandatory nucleic acid test (NAT) blood screening was introduced in Germany in 1999 for hepatitis C virus (HCV) RNA and in 2004 for human immunodeficiency virus Type 1 (HIV-1) RNA. Minimal sensitivity limits of 5000 IU HCV RNA/mL and 10,000 IU HIV-1 RNA/mL were defined for the individual donation facilitating testing of minipools (MPs). The NAT yield obtained from all blood organizations is summarized. Transfusion-associated virus transmissions despite NAT screening ("breakthrough transmissions") are analyzed.

STUDY DESIGN AND METHODS

In Germany, a variety of NAT assays is applied for NAT screening pool sizes of up to 96 donations. Subsets of NAT yield cases were characterized with regard to viral loads by quantitative NAT and with regard to viral genotypes. Confirmed breakthrough transmissions were analyzed using different molecular and serologic assays.

RESULTS

Ninety-two HCV NAT yield cases among 40.8 million and 11 HIV-1 NAT yield cases among 17.1 million donations were identified. During this period, one transmission case was confirmed for HCV and one for HIV-1. The two incidents escaped NAT detection because of low-level viremia and/or suboptimal amplification efficiency. Evidence was obtained for a case of HIV-1 nontransmission by a low-level HIV-1 contaminated red blood cell unit.

CONCLUSION

NAT screening of MPs identified the vast majority of window-phase donations. A significant number of transmission cases was interdicted; breakthrough transmissions may still occur as rare events, even with individual-donation NAT in place. Sensitivity limits might be adapted to the current "state of the art" taking account of viral dynamics during early infection, incidence rates, and costs.

Parvovirus B19 transmission by a high-purity factor VIII concentrate

BACKGROUND

Parvovirus B19 (B19) is known to cause a variety of human diseases in susceptible individuals by close contact via the respiratory route or by transfusion of contaminated blood or blood products. In this study, whether a case of B19 transmission was causally related to the infusion of implicated lots of a solvent/detergent (S/D)-treated, immunoaffinity-purified factor VIII concentrate (antihemophilic factor [human][AHF]) was investigated.

STUDY DESIGN AND METHODS

Anti-B19 (both immunoglobulin M [IgM] and immunoglobulin G [IgG]) and B19 DNA (by a nucleic acid testing [NAT] procedure) were assayed in two implicated product lots, a plasma pool, and a recipient's serum sample. Analysis of the partial B19 sequences obtained from sequencing clones or direct sequencing of the samples was performed.

RESULTS

Only one of the two implicated lots was B19 DNA-positive. It contained 1.3 x 10(3) genome equivalents (geq or international units [IU]) per mL. The negative lot was derived from plasma screened for B19 DNA by NAT in a minipool format to exclude high-titer donations, whereas the positive lot was mostly from unscreened plasma. This high-purity AHF product had no detectable anti-B19 IgG. A 4-week postinfusion serum sample from a recipient, who received both lots and became ill, was positive for the presence of B19 antibodies (both IgM and IgG) as well as B19 DNA. The B19 sequences from the positive lot, its plasma pool, and the recipient's serum sample were closely related.

CONCLUSION

These findings and the recipient's clinical history support a causal relationship between the implicated AHF product and B19 infection in this recipient. The seronegative patient became infected after receiving 2x10(4) IU (or geq) of B19 DNA, which was present in this S/D-treated, high-purity AHF product.