The efficacy of individual-donation and minipool testing to detect low-level hepatitis B virus DNA in Taiwan

An economic reappraisal of hepatitis B virus testing strategy for blood donors in Taiwan

BACKGROUND AND OBJECTIVES

Taiwan is among the few hepatitis B virus (HBV) high-endemic countries that implement universal mini-pool nucleic acid testing (MP-NAT) and hepatitis B surface antigen (HBsAg) testing together with confirmatory individual donor nucleic acid testing (ID-NAT) for its blood supply since 2013. The aim of this study was to reappraise the value of HBsAg test in Taiwan's HBV testing strategy.

MATERIALS AND METHODS

A Markov model was constructed, and cost-effectiveness analysis was conducted in order to reappraise the existing HBV screening strategy in Taiwan.

RESULTS

The incremental cost-effectiveness ratio (ICER) for the current testing strategy in Taiwan was estimated to be $US 443 154 per quality-adjusted life year (QALY) gained. This is almost six times the willingness-to-pay (WTP) threshold that reflects local preferences.

CONCLUSION

Universal HBsAg and MP-8-NAT together with confirmatory ID-NAT testing prevents a significant amount of HBV infections from entering the Taiwan blood supply. However, this comes at a disproportionate increase in cost.

Considerations for Group Testing: A Practical Approach for the Clinical Laboratory

Group testing, also known as pooled sample testing, was first proposed by Robert Dorfman in 1943. While sample pooling has been widely practiced in blood-banking, it is traditionally seen as anathema for clinical laboratories. However, the ongoing COVID-19 pandemic has re-ignited interest for group testing among clinical laboratories to mitigate supply shortages. We propose five criteria to assess the suitability of an analyte for pooled sample testing in general and outline a practical approach that a clinical laboratory may use to implement pooled testing for SARS-CoV-2 PCR testing. The five criteria we propose are: (1) the analyte concentrations in the diseased persons should be at least one order of magnitude (10 times) higher than in healthy persons; (2) sample dilution should not overly reduce clinical sensitivity; (3) the current prevalence must be sufficiently low for the number of samples pooled for the specific protocol; (4) there is no requirement for a fast turnaround time; and (5) there is an imperative need for resource rationing to maximise public health outcomes. The five key steps we suggest for a successful implementation are: (1) determination of when pooling takes place (pre-pre analytical, pre-analytical, analytical); (2) validation of the pooling protocol; (3) ensuring an adequate infrastructure and archival system; (4) configuration of the laboratory information system; and (5) staff training. While pool testing is not a panacea to overcome reagent shortage, it may allow broader access to testing but at the cost of reduction in sensitivity and increased turnaround time.

Highly sensitive and specific detection of hepatitis B virus DNA and drug resistance mutations utilizing the PCR-based CRISPR-Cas13a system

OBJECTIVES

Undetectable or low-level hepatitis B virus (HBV) DNA and drug resistance mutations in patients may increase the risk of HBV transmission or cause active viral replication and other clinical problems. Here, we established a highly sensitive and practical method for HBV and drug resistance detection using a polymerase chain reaction (PCR) -based CRISPR-Cas13a detection system (referred to as PCR-CRISPR) and evaluated its detection capability using clinical samples.

METHODS

Specific CRISPR RNAs (crRNAs) are designed for HBV DNA detection and YMDD (tyrosine-methionine-aspartate-aspartate) variant identification. The HBV DNA was detected in 312 serum samples for HBV diagnosis using quantification PCR (qPCR) and PCR-CRISPR. Additionally, 424 serum samples for YMDD testing were detected by qPCR, direct sequencing, and our assay.

RESULTS

Using PCR-CRISPR, one copy per test of HBV DNA was detected with HBV-1 crRNA in 15 min after PCR amplification. Consistent results with qPCR were observed for 302 samples, while the remaining 10 samples with low-level HBV DNA were detectable by PCR-CRISPR and droplet digital PCR but not by qPCR. PCR-CRISPR diagnosed all 412 drug-resistant samples detected by the YMDD detection qPCR kit and direct sequencing, as well as the other 12 drug-resistant samples with low-level HBV DNA undetectable by qPCR and direct sequencing.

CONCLUSIONS

We developed a novel PCR-CRISPR method for highly sensitive and specific detection of HBV DNA and drug resistance mutations. One copy per test for HBV DNA and YMDD drug resistance mutations could be detected. This method has wide application prospects for the early detection of HBV infection, drug resistance monitoring and treatment guidance.

Recent and occult hepatitis B virus infections among blood donors in the United States

BACKGROUND

Characteristics of US blood donors with recent (RBI) or occult (OBI) hepatitis B virus (HBV) infection are not well defined.

METHODS

Donors with RBI and OBI were identified by nucleic acid and serologic testing among 34.4 million donations during 2009-2015. Consenting donors were interviewed and their HBV S-gene sequenced.

RESULTS

The overall rate of HBV-infected donors was 7.95 per 100,000; of these, 0.35 per 100,000 and 1.70 per 100,000 were RBI and OBI, respectively. RBI (n = 120) and OBI (n = 583) donors constituted 26% of all HBV-infected (n = 2735) donors. Detection of HBV DNA in 92% of OBI donors required individual donation nucleic acid testing. Donors with OBI compared to RBI were older (mean age, 48 vs 39 years; p < 0.0001) with lower median viral loads (9 vs. 529 IU/mL; p < 0.0001). A higher proportion of OBI than RBI donors were born or resided in an endemic country (39% vs. 5%; p = 0.0078). Seventy-seven percent of all RBI and OBI donors had multiple sex partners, an HBV-risk factor. Of 40 RBI and 10 OBI donors whose S gene was sequenced, 33 (83%) and 6 (60%), respectively, carried HBV subgenotype A2; 18 (55%) and 2 (33%), respectively, shared an identical sequence. Infection with 1 or more putative HBV-immune-escape mutants was identified in 5 (50%) of OBI but no RBI donors.

CONCLUSION

RBI and OBI continue to be identified at low rates, confirming the importance of comprehensive HBV DNA screening of US blood donations. HBV-infected donors require referral for care and evaluation and contact tracing; their HBV strains may provide important information on emergent genotypes.

Occult Hepatitis Infection in Transfusion Medicine: Screening Policy and Assessment of Current Use of Anti-HBc Testing

HBV still represents a global risk factor in transfusion medicine. The residual risk of HBV is not limited to pre-seroconversion window period but it extends to donors with occult HBV infection (OBI) characterized by the presence of HBV DNA in liver and by the absence of the virus surface antigen. Each country developed an appropriate blood screening policy according to local HBV prevalence, yields of infectious units per different screening methods and cost-effectiveness. We underline the need of maintaining a high level of attention for OBI carrier identification in all blood banks worldwide where the screening procedures are generally based on a combination of both serological markers and nucleic acid amplification test. In this context, markers such as hepatitis B surface antibodies and hepatitis B core antibodies (anti-HBc) might be useful, although the use of this latter is highly debated and still controversial. Our aim is to give an overview on the relevant diagnostic approaches for the routine screening for HBV focusing on the feasibility of anti-HBc testing as precautionary measure in preventing OBI transmission worldwide. In our tailored algorithm, the loss of about 1% of 'anti-HBc only' donors, does not significantly affect the blood supply while improving recipient safety.

Detection of occult hepatitis B and window period infection among blood donors by individual donation nucleic acid testing in a tertiary care center in South India

With the introduction of highly sensitive hepatitis B surface antigen immunoassay, transfusion associated HBV infection have reduced drastically but they still tend to occur due to blood donors with occult hepatitis B infection (OBI) and window period (WP) infection. Sera from, 24338 healthy voluntary blood donors were screened for HBsAg, HIV and HCV antibody using Vitros Enhanced Chemiluminescent Immunoassay. The median age of the donor population was 30 (range 18-54) with male preponderance (98%). All serologically negative samples were screened by nucleic acid testing (NAT) for viral DNA and RNA. NAT-positive samples were subjected to discriminatory NAT for HBV, HCV, and HIV and all samples positive for HBV DNA were tested for anti-HBc, anti-HBs, HBeAg. Viral load was determined using artus HBV RG PCR Kit. Of the 24,338 donors screened, 99.81% (24292/24338) were HBsAg negative of which NAT was positive for HBV DNA in 0.0205% (5/24292) donors. Four NAT positive donors had viral load of <200 IU/ml making them true cases of OBI. One NAT positive donor was negative for all antibodies making it a case of WP infection. Among OBI donors, 75% (3/4) were immune and all were negative for HBeAg. Precise HBV viral load could not be determined in all (5/5) NAT positive donors due to viral loads below the detection limit of the artus HBV RG PCR Kit. The overall incidence of OBI and WP infections was found to be low at 1 in 6503 and 1 in 24214 donations, respectively. More studies are needed to determine the actual burden of WP infections in Indian blood donors.

Association of preS/S Mutations with Occult Hepatitis B Virus (HBV) Infection in South Korea: Transmission Potential of Distinct Occult HBV Variants

Occult hepatitis B virus infection (HBV) is characterized by HBV DNA positivity but HBV surface antigen (HBsAg) negativity. Occult HBV infection is associated with a risk of HBV transmission through blood transfusion, hemodialysis, and liver transplantation. Furthermore, occult HBV infection contributes to the development of cirrhosis and hepatocellular carcinoma. We recently reported the characteristic molecular features of mutations in the preS/S regions among Korean individuals with occult infections caused by HBV genotype C2; the variants of preS and S related to severe liver diseases among chronically infected patients were also responsible for the majority of HBV occult infections. We also reported that HBsAg variants from occult-infected Korean individuals exhibit lower HBsAg secretion capacity but not reduced HBV DNA levels. In addition, these variants exhibit increased ROS-inducing capacity compared with the wild-type strain, linking HBV occult infections to liver cell damage. Taken together, our previous reports suggest the transmission potential of distinct HBV occult infection-related variants in South Korea.

Occult hepatitis B virus infection and blood transfusion

Transfusion-transmitted infections including hepatitis B virus (HBV) have been a major concern in transfusion medicine. Implementation of HBV nucleic acid testing (NAT) has revealed occult HBV infection (OBI) in blood donors. In the mid-1980s, hepatitis B core antibody (HBc) testing was introduced to screen blood donors in HBV non-endemic countries to prevent transmission of non-A and non-B hepatitis. That test remains in use for preventing of potential transmission of HBV from hepatitis B surface antigen (HBsAg)-negative blood donors, even though anti-hepatitis C virus tests have been introduced. Studies of anti-HBc-positive donors have revealed an HBV DNA positivity rate of 0%-15%. As of 2012, 30 countries have implemented HBV NAT. The prevalence of OBI in blood donors was estimated to be 8.55 per 1 million donations, according to a 2008 international survey. OBI is transmissible by blood transfusion. The clinical outcome of occult HBV transmission primarily depends on recipient immune status and the number of HBV DNA copies present in the blood products. The presence of donor anti-HBs reduces the risk of HBV infection by approximately five-fold. The risk of HBV transmission may be lower in endemic areas than in non-endemic areas, because most recipients have already been exposed to HBV. Blood safety for HBV, including OBI, has substantially improved, but the possibility for OBI transmission remains.

Serological characterization of occult hepatitis B virus infection among blood donors in India

INTRODUCTION

Discovery of hepatitis B infections characterized by the presence of viral genome without detectable HBsAg (Occult Hepatitis; OBI) has initiated a considerable amount of research in this regard. Our study is a serological and molecular characterization of OBI among the donors who donated at our blood bank during the study period.

MATERIAL AND METHOD

During the study period HBsAg ELISA non reactive ID-NAT reactive donors samples were screened for presence of antibody against HBc, HBs and HBe. Molecular analysis of these NAT yield samples was undertaken for detection of the viral load and genotyping.

RESULT

We studied 28,134 HBsAg ELISA non reactive donor samples. On testing them with ID-NAT, HBV DNA was detected in 25 samples. Eighteen samples out of these 25 NAT yield were further worked up. The 66.6% of the NAT yield samples (12 out of 18) were reactive for antibody against HBc. The 25% (3 out of 12) of these NAT yield samples having antibody against core antigen also had antibody against HBs. The 27.7% (5 out of 18) of NAT yield detected by ID-NAT did not have any detectable serological marker in blood. Four out of 12 core antibody positive NAT yield samples had genotype A HBV infection.

CONCLUSION

As per our study molecular detection of HBV DNA by ID-NAT, we were able to analyze 18 HBV NAT yield cases among 28,134 HBsAg ELISA non reactive donors. Out of 18, 12 donors were OBI whereas the rest (6) were in window period (WP yield) of HBV infection. One out of every 3.6 NAT yield detected by ID-NAT was non reactive for all serological markers.

Sensitivity of individual and mini-pool nucleic acid testing assessed by dilution of hepatitis B nucleic acid testing yield samples

Introduction:

For nucleic acid testing (NAT) of blood donations, either the blood samples can be pooled together in a batch of six or eight prior to testing (mini-pool-NAT [MP-NAT]), or the tests can be run on every individual sample (individual donor-NAT [ID-NAT]). It has been debated in various studies whether pooling of samples results in decreased sensitivity of detection as the volume of individual samples gets lesser in a pool. The objective of this study was to investigate the effect of dilution on the sensitivity of tests.

Materials and Methods:

The study was performesd on nine plasma samples which were hepatitis B reactive exclusively by Procleix Ultrio Plus and not by Procleix Ultrio or serology. These nine exclusive UltrioPlus ID-NAT yield samples were diluted in 1:2, 1:4. 1:6 and 1:8 dilutions using previously tested negative plasma and each dilution of every sample along with archived undiluted sample were retested in three replicates with Procleix Ultrio Plus Assay.

Results:

Among NAT yield samples, 88.88% of the samples were detected when retested in ID-NAT in undiluted form. Samples with higher viral load (sample 5 and 6) were detected by all dilutions. When samples with viral load below 20 IU/mL were tested in dilutions of 1:6 or 1:8, only 9 out of 27 replicates (33.33%) were detected. This means that more than 67% of low viral load samples were missed by MP-NAT of 1:6 or 1:8 dilution out of total NAT yield samples.

Conclusion:

Individual Donor NAT is ideal methodology for NAT as dilution due to pooling may miss samples with low viral load as evident in this study.

Hepatitis B virus nucleic acid amplification testing of Australian blood donors highlights the complexity of confirming occult hepatitis B virus infection

BACKGROUND

We present an analysis of the first 2 years of hepatitis B virus (HBV) nucleic acid testing (NAT) of the Australian donor population.

STUDY DESIGN AND METHODS

Between July 5, 2010, and July 4, 2012, all blood donations were screened for HBV DNA and hepatitis B surface antigen (HBsAg). Donors who tested HBsAg negative but HBV NAT positive were assessed as occult hepatitis B infections (OBI) if reactive for antibodies to HBV core antigen (anti-HBc). Donors who were anti-HBc reactive but with nonrepeatable or nondiscriminated NAT results were assessed as HBV inconclusive pending follow-up testing.

RESULTS

During the study period a total of 2,673,521 donations were screened for HBV. Forty-two chronic OBI infections (5.55/100,000 donors) were identified compared to eight acute serologic window period infections (1.06/100,000 donors). Of the 42 OBI cases, 23 (54.8%) were detected the first time they were screened for HBV DNA while 19 (45.2%) gave one or more HBV NAT-nonreactive results before detection. Of 68 donors initially assessed as HBV inconclusive and available for follow-up, 10 later confirmed as OBI cases while 51 were NAT nonreactive but remained anti-HBc reactive and OBI could not be excluded.

CONCLUSION

This study demonstrated a substantially higher prevalence of OBI compared to acute serologic window period HBV infections in Australian blood donors. Follow-up testing of OBI cases indicates that HBV DNA is often only intermittently detectable in OBI, highlighting the importance of including anti-HBc to optimize the HBV testing algorithm.

A pilot study on screening blood donors with individual-donation nucleic acid testing in China

BACKGROUND

Nucleic acid amplification testing (NAT) is not yet obligatory in China for blood donor screening and the risk of enzyme immunoassay (EIA)-negative, NAT-reactive donations in Chinese blood donors has rarely been reported. The aim of this study was to screen a population of Chinese blood donors using a triplex individual-donation (ID)-NAT assay and assess the safety benefits of implementing NAT.

MATERIALS AND METHODS

Between 1st August, 2010 and 31st December, 2011 all donations at a Chinese blood centre were screened individually using the Procleix® Ultrio® assay, a multiplex NAT assay for the detection of hepatitis B virus (HBV) DNA, hepatitis C virus (HCV) RNA and human immunodeficiency virus-1 (HIV-1) RNA. All donations were also screened for HBsAg, anti-HIV and anti-HCV using two different EIA for each marker. Samples with discordant results between NAT and EIA were further tested with an alternative NAT assay (Cobas® TaqMan®). Potential yield cases (serologically negative/NAT-reactive donors) were further evaluated when possible.

RESULTS

During the study period a total of 178,447 donations were screened by NAT and EIA, among which 169 HBV NAT yield cases (0.095%) were detected. No N AT yield cases were found for HIV-1 or HCV. For the HBV NAT yield cases, follow-up results showed that 11 (6.51%) were probable or confirmed HBV window period infections, 5 (2.96%) were chronic HBV carriers and 153 (90.53%) were probable or confirmed occult HBV infections. There was a statistically significant difference between the NAT-positive rates for first-time vs repeat donations (0.472% vs 0.146%, respectively; P<0.001).

DISCUSSION

Our data demonstrate that the potential HBV yield rate was 1:1,056 for blood donations in the Zhejiang province of China. Implementation of NAT will provide a significant increment in safety relative to serological screening alone.

Detection and identification of occult HBV in blood donors in Taiwan using a commercial, multiplex, multi-dye nucleic acid amplification technology screening test

BACKGROUND

The ability of a new generation commercial, multiplex, multi-dye test from Roche, the cobas TaqScreen MPX test, version 2.0, to detect and identify occult HBV infections was evaluated using routine donor samples from Kaohsiung Blood Bank, Taiwan.

STUDY DESIGN AND METHODS

A total of 5973 samples were tested by nucleic acid amplification technology (NAT); 5898 in pools of six, 66 in pools of less than six and nine samples individually. NAT-reactive samples were retested with alternative NAT tests, and follow-up samples from the donors were tested individually by NAT and for all the HBV serological markers.

RESULTS

Eight NAT-only-reactive donors were identified, and follow-up samples were obtained from six of the donors. The results indicated that all eight donors had an occult HBV infection with viral loads <12 IU/ml.

CONCLUSION

The cobas(®) TaqScreen MPX test, version 2.0, has an advantage over the current Roche blood screening test, the cobas TaqScreen MPX test, for screening donations in countries with a high prevalence of occult HBV infections since the uncertainty associated with identifying samples with very low viremia is removed by the ability of the test to identify the viral target in samples that are reactive with the cobas TaqScreen MPX test, version 2.0.

Stochastic model for estimating the risk of transfusion-transmitted hepatitis B in Vietnam

BACKGROUND AND OBJECTIVE

Transfusion-transmitted hepatitis B virus (HBV) infection may originate from hepatitis B surface antigen (HBsAg) false-negative blood donors, HBsAg negative and anti-HBc positive blood donors and blood donors with both tests negative. HBV DNA may be present in all these cases and blood may be infectious. The aim of the study was to estimate the risk of transfusion-transmitted HBV in Vietnam using a stochastic Monte Carlo model.

METHODS

A cross-sectional study of HBV prevalence in 1200 potential blood donors in rural Vietnam is used as basis for the Monte Carlo model together with expert panel estimates of occult hepatitis B infection (OBI) prevalence in blood donors.

RESULTS

With 1 000 000 blood donors running in the model, the potential OBI ranged from 658 to 747 blood units per million at 5 percentile and from 1342 to 2507 blood units per million at 95 percentile resulting in the risk of post-transfusion hepatitis ranging from 66 to 250 blood units per million assuming that risk of post-transfusion from potential OBI is 10%. Using the manufacturer's HBsAg sensitivity, the mean rate of blood units per million donations having false-negative HBsAg results was 298 (5-95 percentile: 14-893). When the test sensitivity was set lower, false-negative tests was observed at a mean of 1087 per million (5-95 percentile: 762-3220). The fraction of potential OBI donors increased with the increasing age in both genders.

CONCLUSION

Current HBsAg screening in Vietnam is insufficient in eliminating the risk of transfusion-transmitted HBV infection. The major risk factors are HBsAg false-negative results and OBI. Increased test sensitivity and locally validated HBsAg assays are recommended.

Residual risk of transfusion-transmitted hepatitis B virus (HBV) infection caused by blood components derived from donors with occult HBV infection in Japan

BACKGROUND

Nucleic acid amplification testing (NAT) for hepatitis B virus (HBV) during blood screening has helped to prevent transfusion-transmitted HBV infection (TT-HBV) in Japan. Nevertheless, 4 to 13 TT-HBV infections arise annually.

STUDY DESIGN AND METHODS

The Japanese Red Cross (JRC) analyzed repository samples of donated blood for TT-HBV that was suspected through hemovigilance. Blood donations implicated in TT-HBV infections were categorized as either window period (WP) or occult HBV infection (OBI) related. In addition, we analyzed blood from 4742 donors with low antibody to hepatitis B core antigen (anti-HBc) and antibody to hepatitis B surface antigen (anti-HBs) titers using individual-donation NAT (ID-NAT) to investigate the relationship between anti-HBc titer and proportion of viremic donors.

RESULTS

Introduction of a more sensitive NAT method for screening minipools of 20 donations increased the OBI detection rate from 3.9 to 15.2 per million, while also the confirmed OBI transmission rate increased from 0.67 to 1.49 per million. By contrast the WP transmission rate decreased from 0.92 to 0.46 per million. Testing repository samples of donations missed by minipools of 20 donations NAT showed that 75 and 85% of TT-HBV that arose from WP and OBI donations, respectively, would have been interdicted by ID-NAT. The ID-NAT trial revealed that 1.94% of donations with low anti-HBc and anti-HBs titers were viremic and that anti-HBc titers and the frequency of viremia did not correlate.

CONCLUSIONS

The JRC has elected to achieve maximal safety by discarding all units with low anti-HBc and anti-HBs titers that account for 1.3% of the total donations.

Role of molecular diagnostics in the management of viral hepatitis B

INTRODUCTION

Despite the availability of a safe and effective vaccine, chronic hepatitis B virus (HBV) infection continues to be a global health concern with an estimated 350 - 400 million people infected worldwide. Globally, HBV is the leading cause of chronic liver disease that may progress to cirrhosis and hepatocellular carcinoma. Therefore, accurate diagnosis and classification of the disease are important to determine whether therapy is needed.

AREAS COVERED

The review contains an overview of recent data on the existing and emerging developments in the molecular diagnostic and monitoring tools for chronic liver disease.

EXPERT OPINION

Monitoring of HBV viral load is the most widely used method in assessing liver disease severity, predicting development of cirrhosis and hepatocellular carcinoma, deciding initiation of antiviral therapy, assessing treatment response as well as early detection of emergence of drug resistance. Some recent studies have downplayed the importance of viral load in HBV management. Phenotyping/genotyping methods can establish emergent resistance to antivirals. Increasing number of reports suggest that clinical outcome and efficacy of antiviral treatment might vary with HBV genotype and precore/core promoter mutants. The importance of covalently closed circular DNA is also becoming apparent in this regard. Further studies on the development of newer molecular methods for a better management of chronic hepatitis B (CHB) will minimize morbidity in CHB.

Hepatitis B virus in transfusion medicine: still a problem?

Hepatitis B virus (HBV) has probably evolved with humans for nearly 35,000 years. HBV diversified into 9 genotypes (A-I) presenting specific features directing epidemiology, clinical expression and testing. Genotypes E and C are more infectious and carry higher risk of chronicity and cancer. HBsAg blood screening implemented 40 years ago enormously decreased the risk of transfusion transmission but the remaining risk requires extremely sensitive nucleic acid testing (NAT) to be removed. Limitations of the host immune system, the impact of immunodeficiency and the mechanisms utilised for viral persistence were recently identified. HBV replication produces excess HBsAg and infectious and defective viral particles but screening assays for HBsAg or viral particles alone do not allow fully efficient detection, making necessary screening for both. The host immune system fails to completely control the virus that escapes and persists unrecognized at very low levels or as immuno-selected variants. Variants may not be identified by assays, explaining false negative results. Specific mutations may affect post-transcriptional mechanisms including HBV RNA splicing. Asymptomatic HBV infected blood donors are at risk of long-term complications through mechanisms to be understood for appropriate counselling. Infectivity of occult HBV infection (OBI) by transfusion appears low, anti-HBc (anti-core antigen) only being more infectious than anti-HBs (anti-S protein) positive units.

Hepatitis B virus nucleic acid testing in Chinese blood donors with normal and elevated alanine aminotransferase

BACKGROUND

Nucleic acid testing (NAT) is currently not a routine donor test in China. The aim of this study was to evaluate the current residual risk of hepatitis B virus (HBV) transmission and the value of ALT testing in preventing HBV infection.

STUDY DESIGN AND METHODS

From January 2008 to September 2009, a total of 5521 qualified donations by routine screening and 5034 deferred donations due to elevated ALT alone were collected from five blood centers. Samples were tested for HBV DNA by triplex individual-donation (ID)-NAT (ULTRIO assay, on the TIGRIS system, Novartis Diagnostics). HBV NAT-reactive samples were further analyzed by HBV serology, alternative NAT, and viral load and were diluted to simulate if they could be detected in a minipool-NAT.

RESULTS

There was no significant difference in the HBV NAT-yield rate between the qualified donations group (5/5521) and the deferred donations group (4/5034). Of these nine potential HBV-yield cases, one donor (11%) was a possible HBV window-period donor, one (11%) was a chronic HBV carrier, and seven (78%) had probable or confirmed occult HBV infections. Of seven potential HBV-yield cases quantified, the viral loads were less than or equal to 70.0 IU/mL. Minipool testing (minipools of 4, 8, and 16 donations) would miss 43% to 79% of the nine HBV-yield donations.

CONCLUSIONS

Based on our findings in qualified donations, we estimate that the nationwide implementation of ID-NAT testing for HBV DNA in China would detect an additional 9964 viremic donations per year. ALT testing seems to have no significant value in preventing transfusion-transmitted HBV infection. ID-NAT versus simulated minipool-NAT using the ULTRIO test demonstrates the benefit to implement a more sensitive NAT strategy in regions of high HBV endemicity.

The clinical significance of occult hepatitis B transfusion in Taiwan--a look-back study

OBJECTIVES

A look-back study was conducted to determine the clinical significance of occult hepatitis B virus (HBV) blood transfusion in an HBV hyperendemic area.

AIM

To improve the blood transfusion safety.

BACKGROUND

Occult HBV is transmissible through blood transfusion in HBV-naÏve recipients. However, its impact on recipients with prevalent HBV infection in HBV hyperendemic areas is unclear.

METHODS/MATERIALS

In 2006, 12 occult HBV blood donors were found from 10 824 repository samples by nucleic acid testing. The 74 corresponding recipients were identified and their pre- and post-transfusion clinical information was gathered, and the living recipients were recalled for follow-up. From the available archival sera, the HBV DNA was examined and sub-genomic sequences between paired donor and recipient were compared using polymerase chain reaction-based assays.

RESULTS

Among the 74 recipients, 18 were still alive and 12 returned to our clinic. From the available serological profiles, 76% of recipients had ongoing or recovered HBV infection before transfusion. Only 24 recipients had available post-transfusion serological profiles and none seroconverted to be hepatitis B surface antigen (HBsAg) positive. Moreover, except for the prior HBsAg carriers, the recipients' HBV DNA levels after transfusion were low (<20 IU/mL). One recipient had identical HBV surface gene sub-genomic sequence (384 nucleotides) to his donor. After transfusion, no recipient developed post-transfusion hepatitis (PTH) and the clinical outcome was good.

CONCLUSION

In HBV hyperendemic areas, occult hepatitis B transfusion might not lead to HBsAg carriage or PTH. The risk of transfusion-transmitted HBV infection was probably lower than that in non-endemic areas because most recipients had already experienced HBV infection.