Low risk of viral infection after administration of vapor-heated factor VIII concentrate. International Investigator Group

Pharmacokinetics, efficacy and safety of IMMUNATE solvent/detergent (IMMUNATE S/D) in previously treated patients with severe hemophilia A: results of a prospective, multicenter, open-label phase III study

BACKGROUND

IMMUNATE Solvent/Detergent (S/D) is a plasma-derived, human factor VIII (FVIII)/von Willebrand factor (VWF) complex subjected to S/D and vapor heat treatment.

METHODS

This prospective clinical study evaluated the pharmacokinetics (PK) (compared to IMMUNATE), efficacy and safety of IMMUNATE S/D in 56 previously treated patients with severe hemophilia A. Subjects received IMMUNATE S/D either on-demand (47/56), as a prophylactic regimen (49/56), or both (40/56).

RESULTS

IMMUNATE and IMMUNATES/D were equivalent with respect to the FVIII and VWF PK parameters assessed. Bleeding episodes (623) were reported in 47/56 subjects. For 89% of episodes, subjects required only 1 infusion with a mean dose of 29.6 IU/kg and 96% of episodes had an excellent or good response. The duration of prophylaxis ranged from 0.1 to 5.2 months. The median number of bleeds per month in subjects on prophylaxis was 0 (range 0-10). No FVIII inhibitory antibodies were observed in 56 subjects after 2,646 treatment exposure days. No related serious adverse events were reported.

CONCLUSION

The introduction of S/D treatment did not alter the PK characteristics and function of VWF and FVIII molecules in IMMUNATE S/D which is effective and safe for treatment of bleeding episodes, management of surgical procedures and prophylaxis.

Consideration in Hemophilia Therapy Selection

The risk of pathogen transmission via clotting factor therapies has been reduced over the last two decades through the development of effective and progressively more sensitive pathogen screening and inactivation methods and the introduction of recombinant clotting factors for hemophilia, beginning with recombinant factor VIII (FVIII) in 1992. However, new understanding about the potential for transmission of an emerging infectious agent through blood and blood products has renewed concerns about vulnerabilities that remain in plasma-derived and some recombinant clotting therapies that still use plasma components during some stages of the manufacturing process. In the 1980s, patients with hemophilia became "canaries in the coal mine" for human immunodeficiency virus (HIV) and hepatitis C virus (HCV) in the blood supply. Moving forward, healthcare providers must continue to take a proactive role in educating themselves about new information regarding emerging pathogens and develop approaches to discussing this risk with their patients as part of their therapy selection process.

Ensuring the biologic safety of plasma-derived therapeutic proteins: detection, inactivation, and removal of pathogens

Human plasma-derived proteins, such as immunoglobulins, coagulation factors, α₁-antitrypsin, fibrin sealants, and albumin, are widely used as therapeutics for many serious and life-threatening medical conditions. The human origin of these proteins ensures excellent efficacy and compatibility but may also introduce the risk of unintentional disease transmission. Historically, only viruses, particularly hepatitis and HIV, have posed serious threats to the safety of these therapeutics. Fortunately, between 1970 and 1990, the molecular biology of each of the major viruses was elucidated. These advances led to the development and implementation of effective donor screening tests, mainly based on immunoassays and nucleic acid testing, which resulted in a significant reduction of disease transmission risk. In addition, viral inactivation and removal steps were implemented and validated by manufacturers, further reducing the risk associated with known, as well as unidentified, viruses. Since the late 1990s, a different class of transmissible agent, referred to as prions, has been identified as a new risk for disease transmission. However, prion diseases are very rare, and prion transmission through plasma-derived proteins has not been reported to date. The prion-related risk is minimized by deferring donors with certain key risk factors, and by the manufacturing processes that are capable of removing prions. Advances in science and pathogen safety-related technology, compliance with good manufacturing practices by manufacturers, and increasingly stringent regulatory oversight, has meant that plasma-derived proteins have been developed into today’s highly effective therapeutics with very low risk of disease transmission.

Short Scar Face-Lift with the Use of Fibrin Sealant

Fibrin sealants have been used in surgical procedures for decades. This article focuses on the short scar face-lift and the applicability of Tisseel fibrin sealant, or "tissue glue," in expediting the healing process in a series of consecutive patients undergoing face-lift surgery. The evolution of the face-lift incision into the short scar and the adjunctive use of the Tisseel fibrin sealant have both resulted in faster recovery.

Pathogen inactivation technology: cleansing the blood supply

The calculated residual infectious risk of HIV, hepatitis B virus (HBV) and hepatitis C virus (HCV) from blood transfusion is extremely low. However, the risk of bacterial contamination remains and a variety of other agents including emerging viruses, protozoa and tick-borne agents threaten blood supplies and undermine public confidence in blood safety. Traditional methods of donor screening and testing have limited ability to further reduce disease transmission and cannot prevent an emerging infectious agent from entering the blood supply. Pathogen inactivation technologies have all but eliminated the infectious risks of plasma-derived protein fractions, but as yet no technique has proved sufficiently safe and effective for traditional blood components. Half-way technologies can reduce the risk of pathogen transmission from fresh frozen plasma and cryoprecipitate. Traditional methods of mechanical removal such as washing and filtration have limited success in reducing the risk of cell-associated agents, but methods aimed at sterilizing blood have either proved toxic to the cells or to the recipients of blood components. Several promising methods that target pathogen nucleic acid have recently entered clinical testing.

The epidemiology of hepatitis C virus infection

The prevalence of hepatitis C virus (HCV) infection varies in different populations, ranging from as low as 0.6% in volunteer blood donors to as high as 80% in injection drug users. The prevalence of HCV in a population can be predicted by risk factors associated with the transmission of infection. These risk factors include injection drug use, blood product transfusion, organ transplantation, hemodialysis, occupational injury, sexual transmission, and vertical transmission. We review the literature regarding the incidence and prevalence of HCV infection and the evidence supporting various modes of HCV transmission.

Treatment strategies in children with hemophilia

Hemophilia is an inherited bleeding disorder caused by quantitative or qualitative defects in the synthesis of factor VIII (FVIII) or factor IX (FIX). Clinically, it is divided into severe, moderate and mild disease depending on the levels of FVIII or FIX in the blood. The bleeding tendency is most pronounced and can start at a very young age in severe hemophilia, which is characterized by repeated hemorrhage into the joints and muscles. Without treatment, these episodes lead to severe arthropathy, and there is also a high risk of lethal cerebral hemorrhage. The treatment of bleeding symptoms requires the correction of the coagulation defect. Factor concentrates have been available for 30 years, initially with the development of cryoprecipitate, subsequently with increasingly purified plasma-derived forms, and ultimately with recombinant clotting factor concentrates. The advantage of this highly effective therapy has been subdued by the outbreak of HIV and Hepatitis C infections in patients with hemophilia treated with factor concentrates which did not have adequate viral inactivation steps in the purification process. Plasma-derived and recombinant factor concentrates are today considered to have a good safety profile, but are only available for a small group of hemophilia patients worldwide. A multidisciplinary team approach is important for early diagnosis, communication with the patient and parents, and to tailor the best treatment possible with the amount of clotting factor concentrates available. The main goal of hemophilia treatment is to prevent bleeding symptoms and allow normal integration in social life. In patients with severe hemophilia, this can best be achieved by early home treatment and primary prophylaxis. Future developments in gene therapy may transform severe hemophilia to a mild form, with no need for regular injections of clotting factor concentrates.

State of care for hemophilia in pediatric patients

On demand treatment of bleeding episodes is still the main approach to hemophilia care of patients of any age. Prompt infusion of coagulation factor concentrate in the home setting allows treatment of hemorrhages at early onset, reducing the incidence of complications and improving the quality of life. Nevertheless, the technological evolution and progressive improvement in the safety of therapeutic products have changed the management of the disease, particularly in children. The current availability of safer concentrates has drastically reduced the risk of transmission of blood-borne infections. Innovative approaches, such as early primary prophylaxis and immune tolerance induction, have become feasible and their introduction represents a major advance in the achievement of the main therapeutic goals: control of the bleeding diathesis and elimination of inhibitors. Prophylactic regimens have been shown to be effective in preventing the occurrence not only of joint bleeding but also of arthropathy when started early in children with severe hemophilia. Inhibitor development still represents the main complication of hemophilia treatment, making concentrate administration ineffective. Immune tolerance induction by daily infusion of coagulation factor concentrate was shown to eradicate the inhibitors in 63 to 83% of patients. These intensive treatment regimens are administered at home to very young children and create the problem of adequate venous access. Subcutaneous venous ports have been used in patients with hemophilia if peripheral veins could not be frequently accessed; however, the risk of infection is an important limit to their use.

Inactivation of parvovirus B19 in coagulation factor concentrates by UVC radiation: assessment by an in vitro infectivity assay using CFU-E derived from peripheral blood CD34+ cells

BACKGROUND

Nonenveloped and thermostable viruses such as parvovirus B19 (B19) can be transmitted to patients who are receiving plasma-derived coagulation factor concentrates treated by the S/D method for inactivating enveloped viruses. Therefore, it is important to develop and validate new methods for the inactivation of nonenveloped viruses.

STUDY DESIGN AND METHODS

Suspensions of B19 in coagulation factor concentrates (FVIII) were irradiated with UVC light. B19 infectivity was determined by an indirect immunofluorescence assay using CFU-E, as a host cell, derived from peripheral blood CD34+ cells. The effects of catechins on B19 infectivity and on FVIII activity after UVC illumination were also examined.

RESULTS

The indirect immunofluorescence assay estimated the B19 infectivity of samples containing virus copies of 10(5) to 10(11) per 10 microL to be a median tissue culture-infectious dose of 10(0.3) to 10(5.4) per 10 microL. B19 was inactivated by 3 log at 750 J per m(2) of UVC radiation and was undetectable after 1000 or 2000 J per m(2) of irradiation. However, FVIII activity decreased to 55 to 60 percent of pretreatment activity after 2000 J per m(2) of UVC radiation. This was inhibited in the presence of rutin or catechins. Epigallocatechin gallate could maintain FVIII activity at almost 100 percent of pretreatment activity after 2000 J per m(2) of UVC radiation, while B19 infectivity was decreased to undetectable levels, which resulted in >3.9 log inactivation.

CONCLUSION

UVC radiation in the presence of catechins, especially epigallocatechin gallate, appears to be an effective method of increasing the viral safety of FVIII concentrates without the loss of coagulation activity.

Risk factors for infection with HBV and HCV in a largecohort of hemophiliac males

BACKGROUND

Before the implementation of donor screening and the development of effective virus-inactivation procedures, persons with hemophilia (PWHs) were at risk of infection with HBV and HCV transmitted through clotting factor concentrates.

STUDY DESIGN AND METHODS

Data collected from the medical records of a cohort of 2,772 males with hemophilia who resided in six states of the United States were used to examine relations between demographic and clinical characteristics and laboratory markers of past or present infection with HBV and HCV using logistic regression.

RESULTS

Test results were available for 60 percent of the cohort. Among those tested, 30 percent were positive for markers of HBV infection and 64 percent for HCV infection. Factors associated with increased odds of positive HBV markers and HCV infection were greater severity of hemophilia, larger amounts of factor use, and HIV infection. Markers of HBV infection persisted in birth cohorts as late as 1992 and those of HCV infections in birth cohorts through 1991. Compared to same-age US males, PWHs born between 1987 and 1989 were more likely to have markers of HBV and HCV infection.

CONCLUSION

PWHs who received clotting factor concentrates before 1990 may be at risk for infection with hepatitis B or hepatitis C and should be tested.

Hepatitis C virus and blood transfusion: past and present risks

The risk of HCV transmission by blood and blood products has been greatly reduced since the early 1980's. Selection of non-remunerated donors, donor selection to prevent HIV transmission, initial surrogate testing in some regions, and introduction of anti-HCV testing have all contributed to this. ALT surrogate testing has become obsolete since the introduction of anti-HCV testing. The residual risk of HCV transmission due to donations in the anti-HCV window period at present is about 1 in 100 000 transfusions of cellular products, and transmission of HCV by plasma products treated with modern inactivation methods such as solvent-detergent treatment, has not been reported. Hemovigilance programmes, which are presently being installed, will provide more data on the safety of blood transfusion. Introduction of HCV nucleic amplification technology (NAT) as a quality control of manufacturing pools for plasma products or as a form of blood donor screening by minipools is anticipated in many European countries for the coming year. Given industrial developments, NAT testing of individual blood donations may become available within the next 2 years. HCV NAT testing will further annihilate the residual risk, and the cost-effectiveness will become relatively low in comparison with other public health measures.

Guidelines on replacement therapy for haemophilia and inherited coagulation disorders in Italy

In the last years, the availability in Italy of technologically advanced products for replacement therapy has produced significant changes in the management of haemophilia and of hereditary bleeding disorders in general. With the aim of a uniform approach to treatment, the Italian Association of Haemophilia Centres express in these guidelines a consensus on therapeutic strategies designed to ensure the highest degree of safety and efficacy for the treatment of inherited coagulopathies. The guidelines provide specific recommendations for the choice of the product according to updated scientific evidence, and advice on optimal dosages for the treatment of rare bleeding disorders. The system for haemophilia care and funding in Italy is briefly described.

Hemostatic efficacy of fibrin sealant (human) on expanded poly-tetrafluoroethylene carotid patch angioplasty: a randomized clinical trial

PURPOSE

The efficacy of solvent-detergent-treated fibrin sealant (human [FSH]) for controlling anastomotic bleeding from expanded polytetrafluoroethylene (ePTFE) patch angioplasty during carotid endarterectomy was evaluated, and FSH was compared with thrombin-soaked gelatin sponge (Gelfoam; TSG).

METHODS

The study was of a randomized, open-label, single-site, single-treatment, parallel design that took place in a referral center with hospitalized patients. Forty-seven adult patients (33 men, 14 women) underwent elective carotid endarterectomy. Patients were randomized to receive either FSH (N = 24) or TSG (N = 23). FSH was obtained as an investigational new drug. FSH was applied as a liquid by means of a dual-syringe technique. Heparin anticoagulation, patch thickness, and suture type were standardized. Two different needle sizes were used (CV-6, PT-13: N = 21 [FSH: N = 10, TSG: N = 11]; CV-6, PT-9: N = 26 [FSH: N = 14, TSG: N = 13]). The FSH or TSG was applied to the ePTFE patch, and then blood flow was restored through the carotid artery. Degree of anticoagulation was assessed by anti-factor Xa activity. The time from restoration of carotid blood flow until achieving hemostasis was recorded. The blood loss from patch suture hole bleeding was measured. Completion intraoperative duplex ultrasound scanning was performed in all cases. Heparin was reversed with protamine sulfate. The primary end point was successful hemostasis within 15 minutes of restoration of carotid blood flow. The secondary end points were the amount of blood loss caused by suture line bleeding and the time to achieve hemostasis.

RESULTS

There was no difference in the number of patients with complete hemostasis at 15 minutes (TSG, 13 of 23; FSH, 12 of 24; P =.77). The measured blood loss was 99.0 +/- 119.9 (SD) mL for TSG, and 105.0 +/- 107.9 mL for FSH (P =.86). The time to hemostasis was the same for both groups (TSG, 16.5 +/- 16.5 minutes; FSH, 16.6 +/- 14.2 minutes; P =.97). Within both treatment groups, the use of larger needles (PT-13) was associated with greater blood loss (FSH, 169.7 +/- 124.2 mL; TSG, 172.7 +/- 151.5 mL) than was the use of smaller needles (PT-9; FSH, 58.8 +/- 66.3 mL; TSG, 34.1 +/- 25.6 mL; P =.036, P =.001, respectively). There were no postoperative strokes or bleeding complications in either group. No abnormalities were shown in either group by means of completion carotid duplex ultrasound scanning.

CONCLUSION

FSH was equivalent, but not superior to, TSG in achieving hemostasis during carotid endarterectomy performed with ePTFE patch angioplasty. Adhesion properties of FSH to ePTFE are possibly different than those to native tissue and warrant additional investigation.

Safety of coagulation factor concentrates

Many of the adverse effects of the early crude plasma-derived concentrates were ameliorated by increasing their purity. Ironically, this strategy may have increased the risks of inhibitor formation and pathogen transmission due to the addition of processing steps which can alter the immunogenicity of clotting factors and the use of very large plasma pools, as dictated by economic considerations. In the absence of extremely sensitive donor screening, these large pools have a high probability of contamination with pathogens, which may be only partially offset by their removal during protein purification. One approach to minimize the risk of viral transmission is to use recombinant clotting factors produced without the use of human or animal plasma proteins at any step in the manufacturing or formulation process. However, as these proteins are synthesized in mammalian cells, even they pose a theoretical risk of pathogen transmission. For plasma-derived concentrates, the initial viral burden is minimized by screening individual donations and plasma pools with tests which detect virus-specific antibodies, protein antigens, or nucleic acid. These techniques are supplemented by non-specific viral reduction steps based on physical partitioning and/or inactivation of pathogens which share chemical or physical characteristics. Prion proteins, the putative causative agents of transmissible spongiform encephalopathies, do not share these characteristics with viruses, and it remains to be determined whether they partition into clotting factor concentrates and whether the current strategies can efficiently remove or inactivate them. For all blood-borne pathogens, active immunization (currently available only for hepatitis B and A) and continued surveillance of susceptible recipients are critical approaches to achieving optimal safety of coagulation factor concentrates.

Treatment of hereditary angioedema with a vapor-heated C1 inhibitor concentrate

BACKGROUND

Hereditary angioedema results from a congenital deficiency of functional C1 inhibitor and is characterized by episodic bouts of edema, which may be life-threatening when they involve the larynx. We evaluated the effectiveness of a C1 inhibitor concentrate in the prevention and treatment of attacks of hereditary angioedema. The concentrate was vapor-heated to inactivate hepatitis and human immunodeficiency viruses.

METHODS

We conducted two double-blind, placebo-controlled studies. The first was a crossover study consisting of two 17-day trials in which prophylactic infusions of either C1 inhibitor (25 plasma units per kilogram of body weight) or placebo were given intravenously every third day to six patients with hereditary angioedema. The second study was conducted in patients with acute attacks of hereditary angioedema and assessed the length of time to a clinical response after infusions of either 25 plasma units of C1 inhibitor per kilogram (55 infusions in 11 patients) or placebo (49 infusions in 11 patients).

RESULTS

The infusions of C1 inhibitor concentrate resulted in close to normal functional levels of C1 inhibitor and C4. As compared with placebo, prophylactic infusions of C1 inhibitor resulted in significantly lower daily symptom scores for the severity of edema of the extremities (P<0.01), larynx (P<0.05), abdomen (P<0.05), and genitourinary tract (P<0.05). Likewise, during the treatment study the time from the start of an infusion to the beginning of improvement in symptoms was shorter for the C1 inhibitor infusions than the placebo infusions (55 vs. 563 minutes, P<0.001). There was no evidence of toxicity.

CONCLUSIONS

Infusions of a vapor-heated C1 inhibitor concentrate are a safe and effective means of both preventing attacks of hereditary angioedema and treating acute attacks.

The choice of plasma-derived clotting factor concentrates

The gloomy picture caused by the AIDS epidemic is now partially lightened by spectacular improvements in therapy. One important step forward toward elimination of the risk of transfusion of blood-borne infections by plasma products was the development of virucidal methods and their application to clotting factor concentrates. Another important advance was the production of ultrapure factor VIII concentrates by immuno-affinity chromatographic techniques. Not only are these concentrates at least as safe as less-pure concentrates in terms of transmission of blood-borne viral infections, but there is also a hint that the deteriorating immune system of HIV-positive haemophiliacs may be stabilized by these highly purified concentrates. Factor VIII produced by recombinant DNA technology is licensed for treatment of haemophilia A. Hopefully, it will be free of the risk of transmitting infections and will be available in sufficiently large amounts to meet the needs of haemophiliacs worldwide. The availability of concentrates containing only factor IX is another substantial step forward in the treatment of haemophilia B, while we wait for the cure of this disease through gene-transfer therapy.

Triosite implants and fibrin glue in the treatment of atrophic rhinitis: technique and results

Nine patients with primary or secondary atrophic rhinitis were treated by narrowing of the nasal fossae using a new surgical technique (derived from the Eryes procedure) in which a Triosite and fibrin glue mixture is implanted via the labial vestibule route. The results were good or excellent in seven patients. No rejections occurred. Osseocoalescence, as evaluated by computed axial tomography at 6 months, was good. Inspiratory intrasnasal pain in patients with postsurgical atrophic rhinitis improved following the operation. The surgical technique, which is quick and easy to perform, avoids the discomfort of nostril closure or the implantation of grafts from other parts of the body. Complicated flap procedures are also avoided.

Homozygous protein C deficiency--management with protein C concentrate

Two unrelated female infants with homozygous protein C (Pr C) deficiency are reported. Both are of U.K. Pakistani origin and in each case the parents are consanguinous. A previous sibling had died in each family. Both sets of parents were shown to be carriers. The concentration of Pr C in both infants was low at birth. Both developed necrotic skin lesions (purpura fulminans) and responded well to Pr C concentrate. Both are developing normally although one has visual impairment due to retinal artery thrombosis which occurred before treatment was commenced. Both infants are treated with intravenous Pr C concentrate administered daily by the parents at home. Studies of the half-life of exogenous Pr C in one of the patients has shown an increase from 2.7 to 10.8 h during the course of treatment thus enabling it to be administered once daily while still maintaining effective plasma concentrations. In the other patient half-life has fluctuated but Pr C is also given once daily. This is the first report of this condition being treated in this way in the United Kingdom.

CONCLUSION

Infusion of Pr C is a safe and efficient way of treating infants with homozygous Pr C deficiency in the medium term.

Low risk of viral infection after administration of vapor-heated factor VII concentrate or factor IX complex in first-time recipients of blood components. International Factor Safety Study Group

BACKGROUND

Vapor-heated human factor VII concentrate and human factor IX complex are both obtained from prothrombin complex, undergo similar methods of manufacture, and are subjected to an identical two-step vapor-heating process for virus inactivation.

STUDY DESIGN AND METHODS

Intermediate-purity vapor-heated human factor VII concentrate and vapor-heated human factor IX complex were monitored for safety with regard to viral infection in the context of an International Factor Safety Study, a prospective study that follows the revised recommendations from the International Congress of Thrombosis and Hemostasis (ICTH). Because the rarity of the respective hereditary deficiencies would have made separate analyses unrealizable, the results were combined for the final analysis. Entry required that patients have no history of transfusion with any blood derivative. After the first infusion of the study drug, patients were monitored for 6 months for the development of non-A, non-B hepatitis (NANBH) and infection with hepatitis B virus (HBV) and for 15 months for infection with hepatitis C virus (HCV) and human immunodeficiency virus (HIV). An event was defined as a positive result on any test for any infection. An alanine aminotransferase level more than 2.5 times the upper limit of normal on two consecutive occasions was defined as an event for NANBH. HBV infection was monitored with tests for three different HBV markers: the HBV surface antigen, antibody against the HBV surface antigen, and antibody against HBV core antigen. HCV and HIV infection were monitored with tests for HCV and HIV antibodies.

RESULTS

The 25 patients who completed the study (1 has not completed the study and 1 dropped out) received a total of 434 infusions comprising 17 different production lots of the concentrates. Twenty patients were analyzable for NANBH and 25 for HCV and HIV infection. Since most patients had been given HBV vaccination, only 4 patients were analyzable for this end point. None of the patients showed evidence of having developed an event. These data satisfy ICTH criteria when the products are considered together, but vapor-heated factor VII concentrate does not qualify alone because there were only five patients in this group.

CONCLUSION

Vapor-heated factor VII concentrate and vapor-heated factor IX complex are associated with a low risk of viral infection. Preliminary results are also presented, indicating that the concentrates are safe with regard to inhibitor development.

Prevalence of infection with the hepatitis C virus among Italian hemophiliacs before and after the introduction of virally inactivated clotting factor concentrates: a retrospective evaluation

In July 1985, all coagulation factor concentrates were withdrawn from the market in Italy and replaced with virally inactivated concentrates. A retrospective survey comparing the prevalence of the antibody to the hepatitis C virus (anti-HCV) in hemophiliacs multitransfused with nonvirally inactivated concentrates until 1985 with that in previously untreated hemophiliacs transfused exclusively with virally inactivated concentrates since 1985 has been conducted in 9 Italian hemophilia centers. The centers, which follow about one-fourth of all the Italian hemophiliacs, provided information about 708 patients infused for the first time before 1985 (group A) and 80 patients infused for the first time between 1985 and 1991 (group B). The prevalence of anti-HCV was 83% (591/708) in group A and 6% (5/80) in group B. For the 5 anti-HCV-seropositive patients from group B, dry heating, hydrophobic interaction chromatography plus dry heating (2 patients), hot vapor and pasteurization were the virucidal methods used for the concentrates implicated in HCV transmission. In the case associated with pasteurization, there is the possibility of intrafamilial transmission of HCV. It appears from this retrospective analysis that there has been a substantial reduction in the risk of HCV transmission since the adoption of virucidal methods. However, these methods do not eliminate completely the risk, which might be further reduced by the recent adoption of anti-HCV screening for plasma donations used to manufacture concentrates.

Clinical evaluation of viral safety of coagulation factor VIII and IX concentrates

Virucidal methods to inactivate infectious agents are based on various methods of heating or chemically treating plasma concentrates of coagulation factors VIII and IX used in the treatment of hemophilia A and B. This clinical evaluation of the viral safety of such 'treated' concentrates is mainly based on the prospective study of previously untreated hemophiliacs by means of clinical and serological markers of viral infection. Although there have been a few focal episodes of human immunodeficiency virus (HIV) transmission by clotting factors, these have been traced to ineffective virucidal methods that are no longer used or to clerical errors during the manufacturing process. Viral inactivation by pasteurization, vapor heating, heating in the lyophilized state at 80 degrees C and addition of solvent/detergent definitely decreases the risk of infection with hepatitis B and C. The current screening of plasma units for antibody to hepatitis C virus prior to inclusion in pools for concentrate production should further decrease the risk of hepatitis C infection. Other viruses, such as parvovirus and the hepatitis A virus, may still cause infections because they are quite resistant to virucidal methods. On the whole, virucidal methods have greatly reduced the risk of new HIV infections and, to a lesser degree, hepatitis.