An international review of the characteristics of viral nucleic acid-amplification testing (NAT) reveals a trend towards the use of smaller pool sizes and individual donation NAT.

BACKGROUND AND OBJECTIVES: Nucleic acid-amplification testing (NAT) is used for screening blood donations/donors for blood-borne viruses. We reviewed global viral NAT characteristics and NAT-yield confirmatory testing used by blood operators. MATERIALS AND METHODS: NAT characteristics and NAT-yield confirmatory testing used during 2019 was surveyed internationally by the International Society of Blood Transfusion Working Party Transfusion-Transmitted Infectious Diseases. Reported characteristics are presented herein. RESULTS: NAT was mainly performed under government mandate. Human immunodeficiency virus (HIV), hepatitis C virus (HCV) and hepatitis B virus (HBV) NAT was performed on all donors and donation types, while selective testing was reported for West Nile virus, hepatitis E virus (HEV), and Zika virus. Individual donation NAT was used for HIV, HCV and HBV by ~50% of responders, while HEV was screened in mini-pools by 83% of responders performing HEV NAT. Confirmatory testing for NAT-yield samples was generally performed by NAT on a sample from the same donation or by NAT and serology on samples from the same donation and a follow-up sample. CONCLUSION: In the last decade, there has been a trend towards use of smaller pool sizes or individual donation NAT. We captured characteristics of NAT internationally in 2019 and provide insights into confirmatory testing approaches used for NAT-yields, potentially benefitting blood operators seeking to implement NAT.

International review of blood donation nucleic acid amplification testing.

BACKGROUND AND OBJECTIVES: Nucleic acid amplification testing (NAT), in blood services context, is used for the detection of viral and parasite nucleic acids to reduce transfusion-transmitted infections. This project reviewed NAT for screening blood donations globally. MATERIALS AND METHODS: A survey on NAT usage, developed by the International Society of Blood Transfusion Working Party on Transfusion-transmitted Infectious Diseases (ISBT WP-TTID), was distributed through ISBT WP-TTID members. Data were analysed using descriptive statistics. RESULTS: Forty-three responses were received from 32 countries. Increased adoption of blood donation viral screening by NAT was observed over the past decade. NAT-positive donations were detected for all viruses tested in 2019 (proportion of donations positive by NAT were 0.0099% for human immunodeficiency virus [HIV], 0.0063% for hepatitis C virus [HCV], 0.0247% for hepatitis B virus [HBV], 0.0323% for hepatitis E virus [HEV], 0.0014% for West Nile virus [WNV] and 0.00005% for Zika virus [ZIKV]). Globally, over 3100 NAT-positive donations were identified as NAT yield or solely by NAT in 2019 and over 22,000 since the introduction of NAT, with HBV accounting for over half. NAT-positivity rate was higher in first-time donors for all viruses tested except WNV. During 2019, a small number of participants performed NAT for parasites (Trypanosoma cruzi, Babesia spp., Plasmodium spp.). CONCLUSION: This survey captures current use of blood donation NAT globally. There has been increased NAT usage over the last decade. It is clear that NAT contributes to improving blood transfusion safety globally; however, there is a need to overcome economic barriers for regions/countries not performing NAT.

Implementation of amotosalen plus ultraviolet A-mediated pathogen reduction for all platelet concentrates in France: Impact on the risk of transfusion-transmitted infections.

BACKGROUND AND OBJECTIVES: Pathogen reduction (PR) technology may reduce the risk of transfusion-transmitted infections (TTIs), notably transfusion-transmitted bacterial infection (TTBI) associated with platelet concentrates (PCs). PR (amotosalen/UVA treatment) was implemented for all PCs transfused in France in November 2017. No bacterial detection was in place beforehand. The study aimed to assess the impact of PR PC on TTI and TTBI near-miss occurrences. MATERIALS AND METHODS: TTI and TTBI near-miss occurrences were compared before and after 100% PR implementation. The study period ran from 2013 to 2022. Over 300,000 PCs were transfused yearly. RESULTS: No PC-related transmission of human immunodeficiency virus, hepatitis C virus, hepatitis B virus and human T-cell lymphotropic virus was reported throughout the study period. PC-mediated hepatitis E virus and hepatitis A virus infections occurred irrespective of PR implementation. Mean PC-mediated TTBI occurrence before PR-PC implementation was 3/year (SD: 1; n = 15; 1/92,687 PC between 2013 and 2016) with a fatal outcome in two patients. Since PR implementation, one TTBI has been reported (day 4 PC, Bacillus cereus) (1/1,645,295 PC between 2018 and 2022; p < 0.001). Two PR PC quarantined because of a negative swirling test harboured bacteria: a day 6 PC in 2021 (B. cereus and Staphylococcus epidermidis) and a day 7 PC in 2022 (Staphylococcus aureus). Five similar occurrences with untreated PC were reported between 2013 and 2020. CONCLUSION: Transfusion of 100% PR PC resulted in a steep reduction in TTBI occurrence. TTBI may, however, still occur. Pathogen-reduced PC-related TTI involving non-enveloped viruses occurs as well.

Human immunodeficiency virus, hepatitis C virus and hepatitis B virus incidence in blood donors from 2000 to 2020 in France: Trends and lessons from haemovigilance surveillance.

BACKGROUND AND OBJECTIVES: Data from 21 years (2000-2020) of haemovigilance were used to assess human immunodeficiency virus (HIV), hepatitis B virus (HBV) and hepatitis C virus (HCV) incidence rates in repeat blood donors and the occurrence of transfusion-transmitted (TT) viral infections. MATERIALS AND METHODS: Blood donors who converted for HIV, HCV or HBV markers within serial three-year analysis periods were included. Epidemiological and virological data were retrieved from the national epidemiological donor database and were supplemented with information on blood components and the infection status of recipients of the previous negative donation (D.N-1) of donors who seroconverted. RESULTS: Incidence rates declined from 1.27 to 0.35/100,000 person-years for HIV, from 0.59 to 0.19 for HCV and from 1.66 to 0.18 for HBV. Risk factors and lookback for 232 HIV, 90 HCV and 74 HBV seroconversions were investigated. The main risk factor identified at post-donation interview was having sex with men (47.8% of males) for HIV and a sexual risk for HCV (30.6%) and HBV (37.1%). The viral loads and sequences were retrospectively tested in 191 HIV, 74 HCV and 62 HBV D.N-1 archived samples. Six (five HBV and one HIV-1) were positive all low viral loads. Two recipients were infected by red blood cells from two HBV seroconverting donors before the introduction of HBV-nucleic acid testing. CONCLUSION: HIV, HCV and HBV incidence rates in blood donors declined over the two past decades in France. There is a very small risk of a blood component that tests negative entering the blood supply resulting in TT infections, especially after introduction of molecular assays in donor screening.

Evolving deferral criteria for blood donation in France: Plasma donation by men who have sex with men.

BACKGROUND AND OBJECTIVES: Since the advent of AIDS, men who have sex with men (MSM) have often been deferred from blood donation. In France, quarantine plasma donation by MSM donors with the same deferral rules as for other donors was introduced in July 2016 and continued up to March 2022. At this time, MSM-specific deferral criteria were lifted for all blood or plasma donation. The donor deferral, as well as rate of infectious markers in plasma donors who would have been otherwise deferred for MSM activity, was evaluated and compared with those of the other donors during the same time period from June 2016 to March 2022. RESULTS: A total of 8843 MSM donors made 12,250 plasma donation applications. The overall deferral rate was very high (75.2%), mainly due to the absence of apheresis capacity at the donation site. The deferral criteria for sexual risk were present in 12.1% of MSM donors compared with 1.0% in other plasma and blood donors (p < 0.001). Overall, 994 MSM donors made 2880 plasma donations. Of these, one donation was HIV positive (34.7 vs. 0.6/105 donations by other donors, relative risk [RR]: 61.0 [95% confidence interval [CI]: 8.5-437.7]), one was HBV positive (34.7 vs. 4.5/105 , RR: 7.7 [95% CI: 1.1-54.6]) and none were HCV positive (0 vs. 2.4/105 ). Additionally, 21 donations were syphilis positive (729.2 vs. 10.7/105 , RR: 67.9 [95% CI: 44.2-104.4]). A post hoc analysis of eligible MSM donors who were unable to donate plasma due to logistic constraints yielded similar findings. CONCLUSION: Plasma donation by donors who would have been otherwise deferred for MSM activity was associated with both an increased deferral rate for sexual risk and an increased rate of infectious markers, notably syphilis.

Are International Units of Anti-HBs Antibodies Always Indicative of Hepatitis B Virus Neutralizing Activity?

OBJECTIVE: Anti-HBs antibodies are elicited upon hepatitis B vaccination, and concentrations above 10 mIU/mL are considered protective. Our aim was to assess the relationship between IU/mL of anti-HBs and neutralization activity. METHODS: Immunoglobulins G (IgGs) were purified from individuals who received a serum-derived vaccine (Group 1), a recombinant vaccine, Genevac-B or Engerix-B (Group 2), or who recovered from acute infection (Group 3). IgGs were tested for anti-HBs, anti-preS1, and anti-preS2 antibodies and for their neutralizing activity in an in vitro infection assay. RESULTS: Anti-HBs IUs/mL value did not strictly correlate with neutralization activity. The Group 1 antibodies demonstrated a greater neutralizing activity than those of Group 2. Anti-preS1 antibodies were detected in Groups 1 and 3, and anti-preS2 in Group 1 and Group 2/Genhevac-B, but the contribution of anti-preS antibodies to neutralization could not be demonstrated. Virions bearing immune escape HBsAg variants were less susceptible to neutralization than wild-type virions. CONCLUSION: The level of anti-HBs antibodies in IUs is not sufficient to assess neutralizing activity. Consequently, (i) an in vitro neutralization assay should be included in the quality control procedures of antibody preparations intended for HB prophylaxis or immunotherapy, and (ii) a greater emphasis should be placed on ensuring that vaccine genotype/subtype matches with that of the circulating HBV.

Seven years (2015-2021) of blood donor screening for HEV-RNA in France: lessons and perspectives.

BACKGROUND: The French health authorities are considering expanding the current selective hepatitis E virus (HEV)-RNA testing procedure to include all donations in order to further reduce transfusion-transmitted HEV infection. Data obtained from blood donors (BDs) tested for HEV-RNA between 2015 and 2021 were used to assess the most efficient nucleic acid testing (NAT) strategy. MATERIALS AND METHODS: Viral loads (VLs) and the plasma volume of blood components, as well as an HEV-RNA dose of 3.85 log IU as the infectious threshold and an assay with a 95% limit of detection (LOD) at 17 IU/mL, were used to assess the proportion of: (i) HEV-RNA-positive BDs that would remain undetected; and (ii) blood components associated with these undetected BDs with an HEV-RNA dose >3.85 log IU, considering 4 NAT options (Individual testing [ID], MP-6, MP-12, and MP-24). RESULTS: Of the 510,118 BDs collected during the study period, 510 (0.10%) were HEV-RNA-positive. Based on measurable VLs available in 388 cases, 1%, 15.2%, 21.8%, and 32.6% of BDs would theoretically pass undetected due to a VL below the LOD of ID, MP-6, MP-12, and MP-24 testing, respectively. All BDs associated with a potentially infectious blood component would be detected with ID-NAT while 13% of them would be undetected with MP-6, 19.6% with MP-12, and 30.4% with MP-24 depending on the plasma volume. No red blood cell (RBC) components with an HEV-RNA dose >3.85 log IU would enter the blood supply, regardless of the NAT strategy used. DISCUSSION: A highly sensitive ID-NAT would ensure maximum safety. However, an MP-based strategy can be considered given that: (i) the risk of transmission is closely related to the plasma volume of blood components; (ii) RBC are the most commonly transfused components and have a low plasma content; and (iii) HEV-RNA doses transmitting infection exceed 4 log IU. To minimise the potential risk associated with apheresis platelet components and fresh frozen plasma, less than 12 donations should be pooled using an NAT assay with a LOD of approximately 20 IU/mL.

Characterization of hepatitis B viral forms from patient plasma using velocity gradient: Evidence for an excess of capsids in fractions enriched in Dane particles.

Hepatitis B virus (HBV) morphogenesis is characterized by a large over-production of subviral particles and recently described new forms in parallel of complete viral particles (VP). This study was designed to depict circulating viral forms in HBV infected patient plasmas, using velocity gradients and most sensitive viral markers. Plasmas from chronic hepatitis B (CHB) patients, HBeAg positive or negative, genotype D or E, were fractionated on velocity and equilibrium gradients with or without detergent treatment. Antigenic and molecular markers were measured in plasma and in each collected fraction. Fast Nycodenz velocity gradients revealed good reproducibility and provided additional information to standard equilibrium sucrose gradients. HBV-RNAs circulated as enveloped particles in all plasmas, except one, and at lesser concentrations than VP. Calculations based on standardized measurements and relative virion and subviral particle molecular stoichiometry allowed to refine the experimental approach. For the HBeAg-positive plasma, VP were accompanied by an overproduction of enveloped capsids, either containing HBs, likely corresponding to empty virions, or for the main part, devoid of this viral envelope protein. Similarly, in the HBeAg-negative sample, HBs enveloped capsids, likely corresponding to empty virions, were detected and the presence of enveloped capsids devoid of HBs protein was suspected but not clearly evidenced due to the presence of contaminating high-density subviral particles. While HBeAg largely influences HBcrAg measurement and accounts for two-thirds of HBcrAg reactivity in HBeAg-positive patients, it remains a 10 times more sensitive marker than HBsAg to characterize VP containing fractions. Using Nycodenz velocity gradients and standardized biomarkers, our study proposes a detailed characterization of circulating viral forms in chronically HBV infected patients. We provide evidence for an excess of capsids in fractions enriched in Dane particles, likely due to the presence of empty virions but also by capsids enveloped by an HBs free lipid layer. Identification of this new circulating viral particle sets the basis for studies around the potential role of these entities in hepatitis B pathogeny and their physiological regulation.

Risk of a blood donation contaminated with hepatitis E virus entering the blood supply before the implementation of universal RNA screening in France.

BACKGROUND AND OBJECTIVES: The risk of a blood donation contaminated with hepatitis E virus (HEV) entering the blood supply before introducing universal HEV-RNA screening in France was estimated to assess the benefit of such a measure. MATERIALS AND METHODS: The results of selective HEV nucleic acid testing (HEV-NAT) performed in mini pool of six plasma donations between 2018 and 2020 were extrapolated to the whole blood donor (BD) population after adjustment on three variables: regional establishment, sex and age group. RESULTS: Among the 246,285 plasma donations collected from 172,635 BDs tested for HEV-RNA, 248 (10.1/10,000) were positive. The extrapolation to all BDs led to an estimated rate of 5.9/10,000 donations (95% confidence interval [CI]: 4.5-7.4) which would be positive to HEV-RNA and a prevalence of 9.9/10,000 BDs (95% CI: 7.5-12.3). This prevalence was 4.4 times higher in males than females (16.8/10,000 vs. 3.8/10,000, p < 10-4 ). The highest prevalence was observed in males in the 30-39 age group (20.5/10,000) and the lowest in females in the 50-70 age group (2.8/10,000). CONCLUSION: The risk of an HEV-RNA-positive donation entering the blood supply was estimated at 1 in 1682 donations. This risk does not translate directly to the risk of HEV transfusion transmission, which mainly depends on the total number of viral particles in the transfused blood component and the sensitivity of NAT.

Insights on 21 Years of HBV Surveillance in Blood Donors in France.

Hepatitis B virus (HBV) infection is the most frequent viral infection found in blood donors (BDs) in France. We analyzed the epidemiological and sero-molecular data on HBV infection gathered over the past two decades by the French haemovigilance surveillance network, blood screening laboratories, and the national reference center for transfusion infectious risks (NRC). Between 2000 and 2020, 6149 of the 58,160,984 donations (1.06/10,000) tested HBV positive, 98% of them from first-time blood donors (FTBDs). In addition, 2212 (0.0071%) of the 30,977,753 donations screened for HBV DNA tested DNA positive, of which 25 (1.1%) were positive only for this marker. HBV prevalence decreased by 2.8-fold and the residual risk for transfusion-transmitted HBV infection decreased 13-fold and was divided by 13. The major risk factor for HBV infection was the origin of donors (endemic country, 66.5%), followed by parenteral exposure (10.7%). In the whole HBV-positive BD population, genotype D was predominant (41.8%), followed by genotypes A (26.2%) and E (20.4%), reflecting the geographical origin of donors. The low and decreasing prevalence and incidence of HBV infection in French BDs, coupled with a screening strategy using three HBV markers (HBsAg, anti-HBc and DNA), ensures a high level of blood safety, further reinforced by the implementation of pathogen-reduction measures.

Multicenter performance evaluation of the Elecsys HCV Duo immunoassay.

BACKGROUND: The diagnostic accuracy of the Elecsys® HCV Duo antigen-antibody combination immunoassay (Roche Diagnostics GmbH) was evaluated for the detection of hepatitis C virus (HCV) infection, versus commercially available comparators. METHODS: This multicenter study (August 2020-March 2021) assessed the specificity of the Elecsys HCV Duo immunoassay and comparator assays in blood donor and routine clinical laboratory samples; sensitivity was determined in confirmed HCV-positive samples and seroconversion panels. The Elecsys HCV Duo immunoassay was compared with the Monolisa HCV Ag-Ab ULTRA V2, Murex HCV Ag/Ab Combination and ARCHITECT HCV Ag assays, as well as nucleic acid testing (NAT). The antibody (anti-HCV) module of the Elecsys HCV Duo immunoassay was compared with the Elecsys Anti-HCV II, Alinity s Anti-HCV, ARCHITECT Anti-HCV and RIBA HCV 3.0 SIA assays. RESULTS: The specificity of the Elecsys HCV Duo immunoassay was 99.94% (95% confidence interval [CI], 99.89-99.97) and 99.92% (95% CI, 99.71-99.99) in blood donor (n = 20,634) and routine clinical laboratory samples (n = 2531), respectively. The specificity of the Elecsys HCV Duo immunoassay was similar or better than comparator assays. The sensitivity of the Elecsys HCV Duo immunoassay in confirmed HCV-positive samples (n = 257) was 99.6%. In seroconversion panels, the Elecsys HCV Duo immunoassay detected infections earlier (2.2-21.9 days) than all but one of the comparator assays and detected HCV 1.8 days later than NAT. CONCLUSIONS: The Elecsys HCV Duo immunoassay shows high diagnostic accuracy, reduces the diagnostic window, and could be used when NAT is not possible.

Anti-HBc-nonreactive occult hepatitis B infections with HBV genotypes B and C in vaccinated immunocompetent adults.

Absence of anti-HBc reactivity with detectable anti-HBs was observed in blood donors with occult hepatitis B virus (HBV) infection (OBI). The prevalence and mechanisms underlying this uncommon condition were investigated over time in Chinese blood donors with OBI. Isolated anti-HBs OBI status was identified from 466,911 donors from Dalian, China, and monitored in follow-up (range: 2.6-84.3 months). HBV vaccination status was documented, and infecting viral strains were characterized. Of 451 confirmed OBIs (1:1035), 43 (9.5%; 1:10,858) had isolated anti-HBs as only serological marker. Isolated anti-HBs OBIs differed from anti-HBc-reactive OBIs by significantly younger age (median 24 years), higher HBV DNA (median: 20 IU/ml) and anti-HBs (median 60.5 IU/L) levels, paucity of mutations in HBV Core and S proteins, and high vaccination rate (72%). Vaccinated isolated anti-HBs OBIs (n = 31) differed from unvaccinated (n = 11) by significantly younger age (22 vs 38 years), higher anti-HBs level at index (48% vs 9% with anti-HBs >100 IU/L) and higher frequency of anti-HBs immune response (44% vs 20%). Of 15 vaccinated and 5 unvaccinated OBIs follow-up, 65% (8 vaccinated and 5 unvaccinated) became HBV DNA negative suggesting aborted recent infection, while 35% (7 vaccinated) had low persistent viraemia 2 to 65 months post index. In conclusion, isolated anti-HBs OBI in Chinese blood donors appears associated with young, vaccinated, adults exposed to HBV who predominantly develop low level aborted infection revealed by transient HBV DNA and immune anti-HBs response. However, a subset of individuals still experienced low but persistent viral replication whose clinical outcome remains uncertain.

Reduced neutralizing antibody potency of COVID-19 convalescent vaccinated plasma against SARS-CoV-2 Omicron variant.

BACKGROUND AND OBJECTIVE: The SARS-CoV-2 Omicron variant displays increased infectiveness as well as mutations resulting in reduced neutralizing activity of antibodies acquired after vaccination or infection involving earlier strains. To assess the ability of vaccinated COVID-19 convalescent plasma (CCP-V) collected before November 2021 to seroneutralize Omicron, we compared neutralizing antibody (nAb) titres of 63 samples against Omicron and earlier B.1 (D614G) strains. METHODS AND FINDINGS: Relationship between anti-Omicron titres and IgG anti-S1 levels (binding arbitrary unit: BAU/ml) was studied. Although correlated, anti-Omicron titres were significantly lower than anti-B.1 titres (median = 80 [10-1280] vs. 1280 [160-10,240], p < 0.0001). Omicron nAb titres and IgG anti-S1 levels were correlated (Spearman's rank correlation coefficient = 0.67). Anti-S1 IgG threshold at 7000 BAU/ml may allow to discard CCP-V without anti-Omicron activity (nAb titre <40). Conversely, only those with highest titres (≥160) had systematically anti-S1 IgG levels >7000 BAU/ml. CONCLUSION: A fraction of CCP-V collected before November 2021 retains anti-Omicron seroneutralizing activity that may be selected by quantitative anti-IgG assays, but such assays do not easily allow the identification of 'high-titre' CCP-V. However, collecting plasma from vaccinated donors recently infected with Omicron may be the best option to provide optimal CCP-V for immunocompromised patients infected with this variant.

SARS-CoV-2 and post-donation information: a one-year experience of the French haemovigilance network.

BACKGROUND: There is growing evidence to support the hypothesis that SARS-CoV-2 is probably not transmissible by blood transfusion. In this study, we use the data gathered over one year by the French haemovigilance network on post-donation information related to SARS-CoV-2, and virological investigations on corresponding plasma to explore viral transmission by transfusion. MATERIALS AND METHODS: Whenever a donor reported COVID-19 symptoms and/or a positive SARS-CoV-2 nasopharyngeal (NP) PCR test, information regarding diagnosis and symptoms was collected using a specific questionnaire, and repository plasmas were screened using the SARS-COV-2 R-GENE® assay (Biomérieux). RNA sequencing (Sanger and deep sequencing) and virus isolation on Vero E6 cells were applied in plasma from donors testing positive. RESULTS: We investigated 1,092 SARS-CoV-2-related post-donation information (PDI) reports. PDI donors were younger than the global donor population and donated more often in the Paris region. Sixty-eight percent reported a positive NP real-time (RT)-PCR or antigenic testing and 22% of these also had symptoms at the time of testing. Thirty-seven (3.4%) donations tested positive for SARS-CoV-2 RNA, 11 (30%) were confirmed by another molecular assay, and 7 (19%) by sequencing, confirming low viral level. Most RNAemic blood donors donated in southern regions and in Paris. There was no difference in demographic data or duration parameter between RNAemic and non-RNAemic donors. Duration parameter was determined as the time elapsed between donation and: i) the onset of symptoms; ii) a positive NP RT-PCR; and iii) PDI. Cell culture experiments did not show any infectivity related to RNAemic plasmas. DISCUSSION: SARS-CoV-2 RNA can be detected in a small fraction of blood donors with PDI, reporting very low levels of RNA. The corresponding plasma is probably not infectious. These findings highlight the value of haemovigilance and PDI to guide blood safety strategies.

Low rate of RNAemia in blood donations collected during the first wave of COVID-19 in France.

BACKGROUND: To investigate the transmission of SARS-CoV-2 via blood, we conducted retrospective molecular screening in blood donated during the first pandemic peak in the two French regions with the highest community transmission. METHODS: Archived plasma samples randomly selected from donations collected between March 23 and 29, 2020, in Eastern and Northern regions of France were tested for SARS-CoV-2 RNA in minipools of 4 donations (MP4) using the Grifols ProcleixSARS-CoV-2 assay. Reactive MP4 and the four corresponding plasmas were further tested with alternative RT-PCRs and sequencing. Testing for SARS-CoV-2 antibodies and in vitro infectivity in cell culture were also performed. RESULTS: Among the 2818 MP4 (corresponding to 9672 donations) tested for viral RNA, 5 were weakly reactive. Among the 20 plasmas included in these five MP4, one presented low-level reactivity with RT-PCRs and Procleix SARS-CoV-2 and was confirmed on sequencing. The estimated prevalence was 1.03/10,000 (95% CI 0-3.1). The 20 plasmas were antibody nonreactive and none of them showed cytopathic effects in cell culture. When recalled, the index-donor declared having had symptoms compatible with SARS-CoV-2 infection a few days after donation. The two immunocompromised recipients transfused with red blood cells and an inactivated pooled platelet product did not develop COVID-19. CONCLUSION: Our results indicated a low prevalence of SARS-CoV-2 RNA in the plasma of asymptomatic blood donors during the pandemic peak and no evidence of infectivity in vivo and in vitro. The transfusion risk remains theoretical and does not justify the implementation of SARS-CoV-2 NAT for blood donations.

Accuracy assessment of total or IgG Immunoglobulin to hepatitis A virus tests around immunity threshold.

BACKGROUND: Anti-hepatitis A virus (HAV) antibody titers at 20 IU/L are assumed to correlate with protection against HAV challenge. METHODS: We examined the accuracy and precision of currently in use immunoassays for total or anti-HAV IgG determination, by repeated testing of dilutions of the international anti-HAV standard, within a 10-50 IU/mL concentration range. RESULTS AND CONCLUSION: Eight immunoassays were evaluated. All could confidently identify people who need to be vaccinated, or who might benefit from a booster vaccine: no positive interpretation for the 10 and 15 IU/mL concentrations. However, qualitative interpretation may differ from test to test in the 15-30 IU/mL range. This variation has to be taken into account when comparing seroprevalence data.

Effectiveness of the HCV blood screening strategy through eighteen years of surveillance of HCV infection in blood donors in France.

BACKGROUND: The question of maintaining blood screening based on both Hepatitis C virus (HCV) infection antibodies (Ab) and Nucleic Acid Testing (NAT) has been raised in several countries. The French blood donor surveillance database was used to address this issue. MATERIALS AND METHODS: In France, HCV-NAT was implemented in mini pools (MP) in 2001 and in individual testing (ID) in 2010. HCV-positive donations are further investigated including detection of RNA with an alternative polymerase chain reaction assay: Amplicor HCV v2.0 (Roche; LOD95 50 IU/mL) from 2001 to 2006 and CobasTaqMan (CTM) HCV 2.0 assay (Roche; LOD95 9.3 IU/mL) since 2007. RESULTS: From 2001 to 2018, 3,058/48.8 million donations were confirmed HCV positive: 64.4% were Ab+/NAT+, 35.1% Ab+/NAT- and 0.5% Ab-/NAT+. From 2001 to 2018, the NAT yield decreased from 0.65 per million donations to 0, and NAT+ donations dropped from 77% to 46% of the total of HCV donations. 2,491/3,058 were further tested for HCV-RNA: 1,032 (816 NAT+, 216 NAT-) with Amplicor and 1,459 (897 NAT+, 562 NAT-) with CTM. Four (3 MP and 1 ID-NAT, 0.5%) of the 778 NAT negative donations had low viral loads. DISCUSSION: The decline in HCV-NAT yield cases raises the question of the relevance of NAT. Conversely, the increase in Ab+/NAT-donors, suggesting a growing number of resolved infections, argue for Ab discontinuation. In our experience, at least 0.5% of Ab+/NAT-donations had low RNA level when retested. Although the risk of viral transmission by such donations is probably low, the uncertainty associated with their infectivity goes against the removal of Ab in blood screening in our country.

Alternative hepatitis B virus DNA confirmatory algorithm identified occult hepatitis B virus infection in Chinese blood donors with non-discriminatory nucleic acid testing.

BACKGROUND: Multiplex viral nucleic acid testing (NAT) and a discriminatory testing algorithm have been used to detect viral infections in blood donors. Non-discriminated reactive (NDR) results may arise from low hepatitis B virus (HBV) DNA levels and are challenging for donor management by blood services. The aim of this study was to evaluate the performance and feasibility of alternative viral particle concentration methods to confirm and to characterise HBV infection status in NDR donors from Dalian, China, in order to improve routine donor management according to the potential residual risk estimate. MATERIALS AND METHODS: Individual donations were tested with ULTRIO Plus, and discriminated when reactive. Virions were concentrated from 12 and 6 mL plasma samples by ultracentrifugation (UC) and polyethylene glycol (PEG) precipitation, respectively. HBV DNA was detected with four nested polymerase chain reactions (95% limit of detection: 5-25 IU/mL). Amplified products were sequenced for definitive confirmation. Anti-HBc and anti-HBs were tested. RESULTS: Of 77,556 donors, 79 (0.1%) were NAT NDR. After viral particle concentration by UC and PEG precipitation, HBV DNA was detected in 46 (58.2%) and 34 (43.0%) NDR donors, respectively, including 61.7% of samples that were repeatedly non-reactive with multiple NAT testing. Anti-HBc and anti-HBs (median titre: 37 mIU/mL) were detected in 87.3% and 46.8% of NDR donors, respectively. Sequencing confirmed HBV DNA in 65.8% of NDR donors, of whom 96.2% were occult HBV carriers with rare mutations in S and core proteins. DISCUSSION: A HBV DNA confirmatory procedure with limited technical constraints was implemented successfully. The majority of NDR donors had occult HBV infections with extremely low viral DNA levels, which may constitute a potential residual threat for blood safety. Only a minority of anti-HBc+ NDR donors had anti-HBs levels high enough to consider their reinstatement as donors. The data support the permanent deferral of NDR donors to ensure maximum blood safety in areas of high HBV endemicity.

New insights into Human Pegivirus-1 (HPgV-1) genotypes diversity in sub-Saharan Africa.

In the framework of a viral discovery research program using metagenomics, Human Pegivirus-1 reads (HPgV-1, formerly known as GBV-C) were detected in plasma pools of healthy blood donors from seven sub-Saharan African countries. For five of these countries, Mauritania, Mali, Niger, Burundi and Madagascar, no data about HPgV-1 genotypes was reported to date. To confirm our metagenomic findings and further investigate the genotype diversity and distribution of HPgV-1 in Africa, 400 blood donations from these five localities as well as from Cameroon, the Democratic Republic of Congo (DRC) and the Burkina Faso were screened with a RT-nested PCR targeting the viral 5'NCR region. Amplified products were sequenced, and the virus was genotyped by phylogenetic analysis. Out of the 400 plasma samples tested, 65 were positive for HPgV-1 RNA and 61 were successfully genotyped. Among these, 54 strains (88.5%) clustered with genotype 1, six (9.8%) with genotype 2 and one (1.6%) with genotype 5. Genotype 1 was observed in all countries studied, except in Madagascar, genotype 2 was detected in Mauritania and Madagascar, and genotype 5 in DRC. Overall, our results extend the geographic distribution of HPgV-1 in Africa and provide six additional nearly complete genomes. Considering that some HPgV-1 genotypes have been reported as potential predictive indicators of lower disease progression in HIV-1 infected subjects, further investigations should be conducted to better understand the positive impact, if any, of this virus.