During the last few decades, efforts to increase the safety of blood and blood products have mainly focused on preventing the viral infections HCV, HIV, HBV and
. The evolution of these approaches ...and the achieved increase in safety is shown for the last 25 years in Switzerland. In detail, the prevalences and incidences of the infection disease and the theoretical estimated residual risks (RR) of these blood-borne infections are presented. Prevalences, incidences and, in particular, the RR have decreased considerably over the last 25 years. This was achieved primarily by the adoption of strict criteria for the selection of blood donors, refined questionnaires, the introduction of increasingly sensitive serological screening tests and the implementation of nucleic acid testing (NAT) for these blood-borne pathogens. These NAT assays have significantly shortened the window period between infection and the first detection of the infectious agent in the blood of an infected individual. A form of "real life" comparison or confirmation is provided by the reported lookback procedures (LBP) and the haemovigilance data of the Swiss competent authority, Swissmedic. These data are in agreement, and thus support the very low prevalences, incidences and RR.
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IZUM, KILJ, NUK, PILJ, PNG, SAZU, UL, UM, UPUK
Introduction
We performed a multicentre evaluation of the Elecsys
®
Anti-SARS-CoV-2 immunoassay (Roche Diagnostics), an assay utilising a recombinant protein representing the nucleocapsid (N) ...antigen, for the in vitro qualitative detection of antibodies to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2).
Methods
Specificity was evaluated using serum/plasma samples from blood donors and routine diagnostic specimens collected before September 2019 (i.e., presumed negative for SARS-CoV-2-specific antibodies); sensitivity was evaluated using samples from patients with polymerase chain reaction (PCR)-confirmed SARS-CoV-2 infection. Point estimates and 95% confidence intervals (CIs) were calculated. Method comparison was performed versus commercially available assays.
Results
Overall specificity for the Elecsys Anti-SARS-CoV-2 immunoassay (
n
= 9575) was 99.85% (95% CI 99.75–99.92): blood donors (
n
= 6714; 99.82%), routine diagnostic specimens (
n
= 2861; 99.93%), pregnant women (
n
= 2256; 99.91%), paediatric samples (
n
= 205; 100.00%). The Elecsys Anti-SARS-CoV-2 immunoassay demonstrated significantly higher specificity versus LIAISON SARS-CoV-2 S1/S2 IgG (99.71% vs. 98.48%), EUROIMMUN Anti-SARS-CoV-2 IgG (100.00% vs. 94.87%), ADVIA Centaur SARS-CoV-2 Total (100.00% vs. 87.32%) and iFlash SARS-CoV-2 IgM (100.00% vs. 99.58%) assays, and comparable specificity to ARCHITECT SARS-CoV-2 IgG (99.75% vs. 99.65%) and iFlash SARS-CoV-2 IgG (100.00% vs. 100.00%) assays. Overall sensitivity for Elecsys Anti-SARS-CoV-2 immunoassay samples drawn at least 14 days post-PCR confirmation (
n
= 219) was 93.61% (95% CI 89.51–96.46). No statistically significant differences in sensitivity were observed between the Elecsys Anti-SARS-CoV-2 immunoassay versus EUROIMMUN Anti-SARS-CoV-2 IgG (90.32% vs. 95.16%) and ARCHITECT SARS-CoV-2 IgG (84.81% vs. 87.34%) assays. The Elecsys Anti-SARS-CoV-2 immunoassay showed significantly lower sensitivity versus ADVIA Centaur SARS-CoV-2 Total (85.19% vs. 95.06%) and iFlash SARS-CoV-2 IgG (86.25% vs. 93.75%) assays, but significantly higher sensitivity versus the iFlash SARS-CoV-2 IgM assay (86.25% vs. 33.75%).
Conclusion
The Elecsys Anti-SARS-CoV-2 immunoassay demonstrated very high specificity and high sensitivity in samples collected at least 14 days post-PCR confirmation of SARS-CoV-2 infection, supporting its use to aid in determination of previous exposure to SARS-CoV-2.
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IZUM, KILJ, NUK, PILJ, PNG, SAZU, UL, UM, UPUK
Introduction
To assess the risk for COVID‐19 of police officers, we are studying the seroprevalence in a cohort. The baseline cross‐sectional investigation was performed before a vaccination campaign ...in January/February 2021, and demonstrated a seroprevalence of 12.9%. Here, we demonstrate serosurveillance results after a vaccination campaign.
Methods
The cohort consists of 1022 study participants. The 3‐ and 6‐month follow‐up visits were performed in April/May and September 2021. Data on infection and vaccination rates were obtained via measuring antibodies to the nucleocapsid protein and spike protein and online questionnaires.
Results
The mean age of the population was 41 (SD 8.8) years, 72% were male and 76% had no comorbidity. Seroconversion was identified in 1.05% of the study population at the 3‐month visit and in 0.73% at the 6‐month visit, resulting in an infection rate of 1.8% over a time period of 6 months. In comparison, the infection rate in the general population over the same time period was higher (3.18%, p = .018). At the 6‐month visit, 77.8% of participants reported being vaccinated once and 70.5% twice; 81% had an anti‐S antibody titer of >250 U/ml and 87.1% of ≥2 U/ml. No significant association between infection and job role within the department, working region, or years of experience in the job was found. Anti‐spike antibody titers of vaccinated study participants showed a calculated decreasing trend 150–200 days after the second vaccine dose.
Conclusion
These data confirm the value of the vaccination campaign in an exposed group other than healthcare professionals.
Graphical
In this serosurveillance study, we observed a high vaccination and low infection rate during the delta surge in a police cohort. Anti‐Spike antibody titers of vaccinated study participants showed a calculated decreasing trend 150–200 days after the second vaccine dose.
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FZAB, GIS, IJS, IZUM, KILJ, NLZOH, NUK, OILJ, PILJ, PNG, SAZU, SBCE, SBMB, UL, UM, UPUK
An important antiinflammatory mechanism of intravenous immunoglobulin preparations (IVIG) is their ability to block complement activation. The purpose of this study was to compare the ...complement-inhibitory activity of four IVIG preparations differing in isotype composition. The preparations were: (1) IVIgG (48 g/L IgG, 2 g/L IgA; Intraglobin F); (2) Pentaglobin (38 g/L IgG, 6 g/L IgM, 6 g/L IgA); (3) IVIgM (35 g/L IgM, 12 g/L IgA, 3 g/L IgG); and (4) IVIgA (41 g/L IgA, 9 g/L IgG), all from Biotest Pharma GmbH, Dreieich, Germany. Their complement inhibitory activity was assessed in vitro by measurement of the blocking of C1q-, C4-, and C3 deposition on solid-phase aggregated rabbit IgG by enzyme-linked immunosorbent assay (ELISA). Complement inhibition in this ELISA was best for IVIgM, followed by Pentaglobin and IVIgG; IVIgA did not exhibit an inhibitory effect. Control experiments with excess concentrations of C1q as well as with C1q-depleted serum showed that the inhibitory effects of IVIG were not caused by complement activation and thus, consumption, but that C4 and C3 were scavenged by IgM and to a lesser extent by IgG. These results were confirmed in vivo in the rat anti-Thy 1 nephritis model, in which a single dose of 500 mg/kg of IVIgM prevented C3-, C6-, and C5b-9 deposition in the rat glomeruli, whereas the effect of IVIgG was much less pronounced. Reduction of complement deposition was paralleled by a diminished albuminuria, which was completely absent in the IVIgM-treated rats. IVIgM and to a lesser extent IVIgG also prevented rat C3 deposition on cultured rat glomerular mesangial cells in vitro, but did not influence anti-Thy 1 binding. Neither IVIgM nor Pentaglobin nor IVIgG negatively affected in vitro phagocytosis of Escherichia coli (E coli) by human granulocytes. In conclusion, we have shown that IgM enrichment of IVIG preparations enhances their effect to prevent the inflammatory effects of complement activation.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
During the last few decades, efforts to increase the safety of blood and blood products have mainly focused on preventing the viral infections HCV, HIV, HBV and Treponema pallidum. The evolution of ...these approaches and the achieved increase in safety is shown for the last 25 years in Switzerland. In detail, the prevalences and incidences of the infection disease and the theoretical estimated residual risks (RR) of these blood-borne infections are presented. Prevalences, incidences and, in particular, the RR have decreased considerably over the last 25 years. This was achieved primarily by the adoption of strict criteria for the selection of blood donors, refined questionnaires, the introduction of increasingly sensitive serological screening tests and the implementation of nucleic acid testing (NAT) for these blood-borne pathogens. These NAT assays have significantly shortened the window period between infection and the first detection of the infectious agent in the blood of an infected individual. A form of “real life” comparison or confirmation is provided by the reported lookback procedures (LBP) and the haemovigilance data of the Swiss competent authority, Swissmedic. These data are in agreement, and thus support the very low prevalences, incidences and RR.
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IZUM, KILJ, NUK, PILJ, PNG, SAZU, UL, UM, UPUK
Background
Nucleic acid test (NAT) hepatitis B virus (HBV) screening for all blood donations with a sensitivity limit of 25 IU/mL in the individual donation is mandatory in Switzerland since 2009. ...The aims of the two studies were to define the percentage of antibody to hepatitis B core antigen (anti‐HBc) or anti‐HBc and antibody to hepatitis B surface antigen (anti‐HBs)‐positive donors bearing HBV DNA and to gather HBV viral load data on HBV NAT yields during the routine screening since the introduction of the HBV NAT.
Study Design and Methods
Archive samples from anti‐HBc–positive donors (Group I) were analyzed with a quantitative HBV DNA test and further with anti‐HBc and anti‐HBs assays. In addition, all the HBV NAT‐only–yield samples (Group II) from the routine donor screening performed between July 2007 and May 2013 were included in the study.
Results
From the 667 samples investigated (131 donors), three donors (2.3%) had donated eight samples (1.2%) with detectable HBV DNA; however, all had very low viral loads (≤10 IU/mL). From the 1,160,426 donations screened with the routine HBV NAT assay, 16 HBV NAT yields were detected: two window period (WP) and 14 occult hepatitis B infection (OBI) cases. In eight of these positive donations (two WP and six OBI), the HBV viral loads were not more than 10 IU/mL, in three cases between 10 and 25 IU/mL, and in the remaining five donations between 37 and 166 IU/mL.
Conclusion
The highly sensitive HBV NAT assay with a threshold significantly below 10 IU/mL is a valuable alternative to anti‐HBc and a less sensitive HBV NAT screening in blood donor screening.
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>bold<>italic<Introduction:>/italic<>/bold< A highly sensitive and specific nucleic acid test (NAT) for the blood-borne viruses human immunodeficiency virus (HIV), hepatitis C (HCV), and hepatitis B ...(HBV) is essential for the safety of blood components. Since more than 2 decades, NAT screening of blood donations has become standard in developed countries that have implemented the individual-donation (ID-NAT) and mini-pool NAT (MP-NAT) approaches. With this powerful technique, confirmation of initial reactive (IR) NAT samples becomes a challenge. Different algorithms are currently in use to eliminate false reactive results. To show that the algorithm implemented in 2007, that uses repeat testing of IR samples in duplicate runs, is a safe strategy, especially in low endemic countries, data from a 10-year experience of ID-NAT were extensively analyzed when follow-up data were available. >bold<>italic<Methods:>/italic<>/bold< From July 2007 to December 2014, the Procleix Ultrio assay on a Procleix Tigris system, and from January 2015 to December 2017, the cobas MPX on a cobas 8800 platform, were used for ID-NAT screening. All IR samples were subjected to repeat testing in duplicate independent runs. Only when both tests remained negative were the products released. Donor data from the last 10 years were investigated retrospectively, looking for the reoccurrence of a reactive result in a follow-up sample. Only those donors with at least an x + 1 donation result were included for the confirmation of a false reactive result. >bold<>italic<Results:>/italic<>/bold< From the 1,830,657 donations tested, 2,450 samples were IR (0.13%); only 228 were repeat reactive (RR, 18 HIV, 61 HCV, and 149 HBV samples), and 2,222 were non-RR (0.12%). Follow-up data were available from 1,267 donors (57%) for further analysis. All except one of these donors were ID-NAT-negative in all follow-up samples. The one exception was from a donor who acquired a fresh HBV infection 10 years after the IR donation (in the x + 28 donation) and subsequently seroconverted. Subsequent serological tests from all succeeding donations (x + 1, x + 2, etc.) were negative in all the other cases, proving that no seroconversion took place after the IR ID-NAT result. >bold<>italic<Conclusions:>/italic<>/bold< The algorithm to deal with IR ID-NAT donations using duplicate repeat testing is very safe and cost-effective in low-prevalence countries. There is no unnecessary destruction of blood products, no counseling of false reactive donors, and also no need to add further complexity to the screening algorithm.
Background: Population migrations and overseas recreational travel to regions at risk for tropical diseases are increasing. A major challenge in non-endemic countries is to decrease the number of ...blood donor deferrals due those tropical disease pathogens, without compromising the high level of blood safety. The protozoans Trypanosoma cruzi and Plasmodium spp., the causative organisms of Chagas disease (CD) and malaria are becoming a major focus in the blood transfusion community. Methods: National guidelines of the Blood Transfusion Service of the Swiss Red Cross propose an algorithm for dealing with these pathogens, including a mandatory selective serological testing of donors at risk. Results: 6,978 donors at risk for CD were tested. Three of them were confirmed anti-T. cruzi-positive, and in one case a transfusion-transmitted infection was highly possible. The specificity of the assay was 99.94%. For malaria 12,887 donors were at risk and 178 were confirmed positive. The specificity of the assays was 92.8%. Conclusion: CD and malaria in non-endemic countries may represent a certain risk for blood transfusion. Switzerland chose a selective testing approach. The specificity of the assays is a crucial topic for this approach because it ensures a minimal loss of false-reactive donors and helps towards an easier counselling of implicated donors.
Background and aimHepatitis E virus (HEV) is a virus of emerging importance to transfusion medicine. Studies from several European countries, including Switzerland, have reported high seroprevalence ...of hepatitis E as a consequence of endemic infections. Published HEV seroprevalence estimates within developed countries vary considerably; primarily due to improved diagnostic assays. The purpose of this study was to investigate the seroprevalence of anti-HEV IgG in Swiss blood donations.
We used the highly sensitive Wantai HEV IgG EIA and assessed regional distribution patterns. We analysed age- and sex-matched archive plasma dating back 20 years from canton Bern to investigate recent changes in HEV seroprevalence levels.
On average, 20.4% (95% confidence intervals: 19.1-21.8) of the 3,609 blood samples collected in 2014-16 were anti-HEV IgG positive; however, distinct differences between geographical regions were observed (range: 12.8-33.6%). Seroprevalence increased with age with 30.7% of males and 34.3% of women being positive donors over > 60 years old. Differences between sexes may be attributed to dissimilarities in the average age of this group. Within the specified region of the Bern canton, overall prevalence has declined over two decades from 30.3% in 1997/98 to 27.0% in 2006 and 22.3% in 2015/6.
HEV seroprevalence in Switzerland is high, but has declined over the last decades. The result shows that primarily endemic HEV infections occur and that current blood products may pose a risk to vulnerable transfusion recipients. Nucleic acid screening of all blood products for HEV will begin in November 2018.
In a COVID‐19 sero‐surveillance cohort study with predominantly healthy and vaccinated individuals, the objectives were (i) to investigate longitudinally the factors associated with the quantitative ...dynamics of antispike (anti‐S1) IgG antibody levels, (ii) to evaluate whether the levels were associated with protection from SARS‐CoV‐2 infection, and (iii) to assess whether the association was different in the pre‐Omicron compared with the Omicron period. The QuantiVac Euroimmun ELISA test was used to quantify anti‐S1 IgG levels. The entire study period (16 months), the 11‐month pre‐Omicron period and the cross‐sectional analysis before the Omicron surge included 3219, 2310, and 895 reactive serum samples from 949, 919, and 895 individuals, respectively. Mixed‐effect linear, mixed‐effect time‐to‐event, and logistic regression models were used to achieve the objectives. Age and time since infection or vaccination were the only factors associated with a decline of anti‐S1 IgG levels. Higher antibody levels were significantly associated with protection from SARS‐CoV‐2 infection (0.89, 95% confidence interval CI 0.82–0.97), and the association was higher during the time period when Omicron was predominantly circulating compared with the ones when Alpha and Delta variants were predominant (adjusted hazard ratio for interaction 0.66, 95% CI 0.53–0.84). In a prediction model, it was estimated that >8000 BAU/mL anti‐S1 IgG was required to reduce the risk of infection with Omicron variants by approximately 20%–30% for 90 days. Though, such high levels were only found in 1.9% of the samples before the Omicron surge, and they were not durable for 3 months. Anti‐S1 IgG antibody levels are statistically associated with protection from SARS‐CoV‐2 infection. However, the prediction impact of the antibody level findings on infection protection is limited.
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