56. Jahrestagung der Deutschen Gesellschaft für Transfusionsmedizin und Immunhämatologie

Vorsitz

Immunoadsorption as a method of antibody donation during the Covid-19 pandemic

Background In the fight against the Covid-19 Pandemic, administration of plasma from convalescent donors containing anti-SARS-CoV-2 antibodies, though promising according to case reports, failed to show a clear benefit in a greater number of trials. We hypothesize that instead of collecting whole plasma units, convalescent donors could donate solely immunoglobulins by undergoing immunoadsorption, a mode of therapy regularly applied in autoimmune diseases.Methods Immunoadsorption using an affinity column adsorber pair (TheraSorb, Miltenyi Biotech) was performed on 6 convalescent plasma donors (4 male and 2 female) that had been tested positive for COVID-19 prior to antibody donations. The resulting eluate contained IgG, IgA and IgM dissolved in a glycine buffer. For bioburden reduction, a Tangential Flow Filtration System (Centramate LV, Pall Corporation) was used to concentrate the eluate and exchange glycine for 0.9% NaCl using diafiltration. The final antibody concentrate was finally sterile filtered, before storage at 4°C or freezing at -80°C.Results Immunoadsorptions were very well tolerated with no side effects. Collected and neutralized eluates were concentrated using Tangential Flow Filtration. The concentrates contained three times more IgG, IgA and IgM as well as specific SARS-CoV2 N and S antibodies compared to the peripheral blood of the donors. The specific SARS-CoV2 virus neutralization capacity was not diminished but rather increased in all but one donation. All ACs passed sterility tests at the collection day and could be stored at -80°C and 4°C with minor loss of function.Conclusion Immunoadsorption proved to be a feasible method of antibody donations for the collection of IgG, IgA and IgM as well as SARS-CoV2 N and S specific antibodies. The antibody concentrates could be produced within one day and final antibody neutralization titers in the ACs were found to be comparatively high. All ACs were sterile, free of hazardous glycine levels and could possibly be administered as a potential therapeutic approach.Offenlegung Interessenkonflikt: Jannik Rothenburg is employed by PALL Corporation Silke Rink-Baron is an employee of Miltenyi Biotec. Lisa Mueller, Philipp Niklas Ostermann, Johannes C. Fischer, Derek Hermsen, Johannes Stegbauer and Anja Moldenhauer have nothing to disclose.

COVID-19

ePoster

PD Dr.

Prof. Dr.

Univ.-Prof. Dr.

Reactivation of Epstein-Barr-Virus is not causative for post-COVID-19-syndrome

Background Post-COVID-19-Syndrome (PCS) frequently occurs after an infection with severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) and is a long-lasting health impairment with a broad range of symptoms. Currently the causative mechanisms remain elusive. Aim of this study was to investigate the PCS rate of SARS-CoV-2 seropositive blood donors as representatives of supposedly healthy adults (n = 400) and to examine whether Epstein-Barr-Virus (EBV) is reactivated in individuals reporting PCS. Methods To ensure that a SARS-CoV-2 infection was experienced, SARS-CoV-2 anti-N total antibodies, which are produced after an infection only, were monitored by an electrochemiluminescence immunoassay (ECLIA). Participants had to fill in questionnaires regarding the time and course of the infection and persisting symptoms, allowing the determination of the PCS rate. Applying ECLIA, the levels of EBV viral capsid-antigen (VCA) IgM, IgG and EBV nuclear antigen 1 (EBNA) IgG were determined. In addition, we performed qRT-PCR to detect EBV DNA. Furthermore, we examined the amount of neopterin, a prognostic marker for a pro-inflammatory immune status, by an enzyme-linked immunosorbent assay (ELISA) and compared it to pre-pandemic values.Results Our data reveal that 18% of SARS-CoV-2 infections result in PCS, with symptoms lasting for up to one year. Quantity and functionality of specific SARS-CoV-2 antibodies were declining in individuals with and without PCS over time, excluding unrecognized reinfections with SARS-CoV-2. All individuals reporting PCS were screened negative for EBV DNA. Furthermore, antibody profiles of VCA IgM, IgG and EBNA IgG revealed past EBV infections in all individuals screened but did not indicate an acute phase of EBV infection after a SARS-CoV-2 infection. Additionally, no elevated levels of neopterin could be found, indicating no pro-inflammatory immune status or enhanced macrophage-related antiviral immune response compared to individuals without PCS.Conclusion Our data did not reveal detectable levels of EBV DNA, a specific antibody response, pro-inflammatory immune status or macrophage-related immune response in healthy adults reporting PCS. Therefore, our study indicates that PCS in immunocompetent adults may not be explained by a reactivation of EBV or by persisting inflammatory processes. Further examination is required to identify the cause of PCS.Offenlegung Interessenkonflikt: none.

SARS-CoV2 mRNA vaccine-specific B-, T-, humoral responses in pediatric stem cell transplant recipients – Importance of a booster vaccination

Background Stem cell transplant recipients (SCTR) suffer from increased COVID-19-associated risks and higher mortality rate than determined for the general population, supporting the need for effective vaccination strategies. Data on immunogenicity of SARS-CoV2 mRNA-based vaccination is limited and it remains largely unaddressed whether and how SARS-CoV2-vaccination-specific humoral and cellular immunity is altered in stem cell transplant recipients, particularly in pediatric cohorts.Methods In this observational study we comprehensively analyzed mRNA vaccine induced humoral and cellular responses after second and third vaccination in pediatric SCTR aged 2-19 years and age-matched healthy children 5 weeks post-vaccination. Vaccine-specific IgG, IgA and Omicron variant neutralizing capacity was assessed by ELISA together with extensive quantification and functional characterization of spike protein-specific B- and T cells by flow cytometry. Spike-specific CD4+ T cells were identified according to the co-expression of CD137 and CD154 after peptide mix stimulation and vaccine-specific B cells were detected by co-staining with fluorescently labeled recombinant receptor binding domain protein and recombinant full spike protein.Results After third vaccination, SCTR reached similar levels of vaccine-specific IgG, IgA and neutralizing antibodies against omicron variant as controls. Although patients showed an increase in frequencies of SARS-CoV2 specific B cells after this booster vaccination, overall frequencies were still fourfold reduced compared to controls. While the majority of individuals enrolled mounted SARS-CoV2 Spike protein-specific CD4+ T helper cell responses, SCTR were characterized by elevated frequencies of vaccine-specific CD4+ T cells compared to controls. Functional analysis revealed significantly diminished portions of specific CD4+IFNγ+ T cells along with an increase in IL-2 producers after the second and third dose in patients compared to controls.Conclusion Our data show multiple quantitative and functional impairments of SARS-CoV2 specific cellular immunity in pediatric SCTR. Moreover, they underline the need of a third vaccine dose for SCTR for mounting sufficient humoral responses, particularly with respect to development of neutralizing antibodies. On the background of vaccination hesitancy amongst parents of SCTR, transplant pediatricians are urged to provide COVID-19-related education and information to protect this vulnerable patient group.Offenlegung Interessenkonflikt: All authors have nothing to disclose.

Validation of a modified rapid antibody test to identify COVID-19 patients with low neutralizing antibody titers in an outpatient setting

Background Primary aim of the presented project was to establish an assay, which allows rapid identification of patients with low anti-SARS-CoV-2 IgG titers in an outpatient setting. Such patients may be eligible for recruitment into the COVIC-19 study and may benefit from treatment with high-titer COVID-19 convalescent plasma.Methods For the validation, the rapid test from Canea for qualitative detection of neutralizing antibodies against SARS-CoV-2 in human serum, plasma or whole blood samples was used. The test cohort included 80 samples from 35 SARS-CoV-2-positive patients. Whole blood (EDTA) and corresponding serum samples were acquired before and on days 3, 14 and 28 after convalescent plasma administration. Modification of the test included a defined pre-dilution of whole blood samples with D-PBS and the introduction of a 5-level grading system to visually evaluate the test results. The main acceptance criterion was a negative predictive value of &gt; 90% to detect a serum antibody concentration of ≤ 700 BAU/ml in the samples.Results With 94.6%, the negative predictive value met the required main acceptance criterion. The overall concordance rate between quantitative anti-spike IgG titers and the results of the modified Canea COVID-19 rapid test was 95%. Furthermore, the analysis showed a highly significant correlation between the rapid test results (5-level grading) and the quantitative antibody measurements (BAU/ml), thereby confirming the semi-quantitative validity of the modified rapid test system (Fig. 1, Pearson, *** p &lt; 0.0001).Conclusion The modified test system from Canea was successfully validated and allows patients with anti-SARS-CoV-2 IgG titers &lt; 700 BAU/ml to be recognized with minimal equipment using whole blood samples. Based on this test method, potential subjects benefiting from a treatment with high-titer convalescent plasma can be easily identified in an outpatient setting. Offenlegung Interessenkonflikt: Keine Interessenkonflikte.

Is immunoapheresis a therapeutic option for post-COVID patients? Data presentation in the treatment of ME/CFS, Post Covid, Post Vaccine (Long Covid syndrome) with immunoadsorption

Background Infection-triggered disease onset, chronic immune activation and autonomic dysregulation in CFS point to an autoimmune disease directed against neurotransmitter receptors. Autoantibodies (Aab) against G-protein coupled receptors were shown to play a pathogenic role in several autoimmune diseases. Therapeutic approaches can be based on the principle of reduction of agonistic Aab. These principles could therefore lead to an improvement in the quality of life of Long Covid patients.Methods All eligible Patients with long COVID (n=) and ME/CFS (n=) received IA (primary device: Spectra Optia, Terumo BCT, Inc. Lakewood, USA/TPE; secondary device: ADAsorb medicap clinic, Ulrichstein, Germany TheraSorb Ig omni 5 Adsorber Miltenyi Biotec B.V. &amp; Co. KG, Bergisch Gladbach, Germany). Patients received 5 treatments on 5 consecutive days. The 2.0-fold individual total plasma volume was processed on days 1–5. Blood was drawn immediately before and after the IA session from an antecubital vein. Patients were followed up directly after last apheresis. The primary endpoint was to remove the autoantibodies and to lower plasma IgG to levels below 2 g/l after the last treatment.Results Between January and December 2022, 99 patients (w=54, m=45), were screened for eligibility, most of them between 30 and 50 years old (&lt; 30 (n=25), 30-39 (n=30), 40-49 (n=24), 50–70 (n=20)).The removal of IgG was successfully high (IgG lowering about 90 %). The symptom descriptions of the patients before and after IA suggest that solely using the evaluation of the Bell score does not reliably reflect the predominantly positive development after IA treatment, since patients have other main problems beside exhaustion! Our specially developed questionnaire shows improvement for most of the treated patients; e.g: How have your symptoms changed since your treatment at the DHZ? -&gt; About 71% improved, 15,5% unchanged, about 14% deteriorated.Conclusion IA is a safe and efficient method for the removal of (auto-)antibodies. A clinical benefit could be demonstrated in most of the patients, but larger trials are needed. Ideally, the free and bound Aab are measured after treatment (antibody screening/biopsy). Maintenance therapy could be a further indication to prevent relapses caused by trigger factors (e.g. infection, vaccination, stress). The treatment decision of the involved physician should be used for a follow-up treatment after IA.Offenlegung Interessenkonflikt: Keine

Prof.

Prevalence of wildtype and vaccination induced SARS-CoV2 antibodies in a blood donor population

Background SARS-CoV-2 (=COVID19) has been a new challenge for health care systems around the world. Blood donation centers were also affected. At some point, vaccination against the virus was possible. In order to examine the prevalence of infections in vaccinated and non-vaccinated donors we performed a prospective observational, single-center study for antibodies against COVID19 ("wildtype" and "vaccination induced") from February until May 2022.Methods After their written informed consent participants were asked to complete a questionnaire about the number of vaccinations against SARS-CoV2 and any known COVID-19 infection. In addition, antibodies against the N-antigen ("nucleocapsid" of the wildtype virus) and the S-antigen ("spike antigen", vaccination induced) were detected via enzyme immune-essays (ECLIA-testing system, Cobas, Roche Diagnostics Mannheim). Laboratory results were compared with the provided information in the questionnaire with a special focus on unrecognized infections.Results 2157 donors were tested between February and May 2022. 92% of them were vaccinated, 4% were not and 4% declined providing information on their vaccination status. Most of the donors (60-80%, depending on the number of vaccinations) were immunized by mRNA-vaccines such as Comirnaty or Spikevax (no matter whether it was the first, second, third, or the fourth vaccination). 398 donors were infected despite being fully vaccinated (18 %). These infections occurred mostly after at least 50 days after the last dose. There were no significant differences between the immunization schedules of the donors. 79 infections with SARS-CoV2 had been unrecognized and were only detected due to this study.Conclusion This single center study showed the success of vaccinations as well as the prevalence of seropositive donors from February until May 2022. By offering antibody testing, the blood donation center was able to address many first-time donors, so besides the study results, this study turned to a successful advertising campaign as well. Interestingly, approximately 24,7 % of infections with SARS-CoV2 had been unrecognized by the respective donor.Offenlegung Interessenkonflikt: The authors have no conflicts of interest to declare. All co-authors have seen and agree with the contents of the manuscript and there are no financial interests to report. We certify that the submission is an original work and is not under review at any other publication.

Immune adsorption as an individual experimental therapy in two patients with multiple autoantibodies and post-COVID-19 syndrome

Background Autoantibodies (AABs) against G-protein-coupled-receptors (GPCRs) may underlie the symptom complex of cognitive and physical deficits in patients with post-COVID-19 syndrome (PCS). Based on this assumption, the hypothesis arose that an AAB removal therapy, e.g. immunoadsorption (IA), could causally lead to symptom relief. To investigate this, we performed IA in two patients using the LIFE21 system and adsorbers Omni 1 and 5, respectively.Methods Two patients (f28; m36) with PCS and pre-known AABs against GPCRs each received one cycle IA (5 treatment days) using the LIFE21 system (Miltenyi Biotec, Germany) with the Omni 1 adsorber (f28) and the Omni 5 adsorber (m36). Myalgic Encephalomyelitis/Chronic Fatigue Syndrome (ME/CFS) was evaluated by the Bell fatigue scale before and after completion of the IA cycle, and immunoglobulins (IgG, IgM, IgA, IgE) were analyzed (Cobas ProRoche) before and after each IA session. At time points before and after each completed IA cycle, relevant pre-existing AABs against β1-/ β2- adrenergic and M3-/ M4- muscarinic acetylcholine receptors and angiotensin II type I receptors (ELISA, IMD laboratory, Berlin) were determined.Results IA sessions with the adsorbers Omni 5 (m36, 5x IA over 13 days) and Omni 1 (f28, 5x IA spread over 44 days - interrupted for 35 days after day 1 due to SARS-CoV-2 re-infection) were clinically well tolerated, and mean plasma volumes treated were 1.3-fold for m36 and 1.8-fold for f28. For each IA, average IgG reduction was 57.1% (m36) and 70.2% (f28). When comparing baseline to final, IgG was reduced by 88.4% (m36) and 90.4% (f28). Elevated AABs (pre-treatment: m36: ß1, ß2, M3, M4, ATII-T1; f28: ß1, ß2, M3, ATII-T1) fell below their reference values in both patients after the IA cycle. Bell fatigue scale did not change when comparing results before/ after the IA cycle and about 4 weeks after (f28: 20/20/10; m36: 50/50/50).Conclusion The Omni 1 and Omni 5 adsorbers are highly capable of removing immunoglobulins non-selectively in a safe and tolerable setting. In both patients, IA was technically successful without the need to treat extraordinary high plasma volumes. However, Bell fatigue scale indicated no improvement in ME/CFS in both patients. Hence, the present investigation does not support a causal relationship between elevated AABs against GPCRs and ME/CFS symptoms.Offenlegung Interessenkonflikt: Techniqual equipment and consumable material was provided by Miltenyi Biotec, Germany.

Autoantibodies against G-protein-coupled receptors can be detected in post/long-COVID-19 patients with fatigue syndrome (ME/CFS) as well as in healthy blood donors

Background Several providers of therapeutic apheresis hypothesize that autoantibodies (AABs) against G protein-coupled receptor (GPCRs) play a crucial role in the development of post-COVID Myalgic Encephalomyelitis/Chronic Fatigue Syndrome (ME/CFS). Their detection is used as an indication for multiple sessions of immune adsorptions as experimental treatment. We investigated whether such AABs also occur in healthy subjects, such as blood donors, in addition to patients with post-COVID ME/CFS.Methods Serum samples from 41 healthy platelet donors and 8 employees of the department for Transfusion Medicine were tested for 5 different AABs against GPCRs: ß1-, ß2-adrenergic receptor-AABs, M3-, M4-muscarinic acetylcholine receptor-AABs and anti-AT1R. The frozen samples (-80°C) were sent to a special laboratory (IMD Labor Berlin). The IgG type AABs were determined using commercial ELISA kits (CellTrends GmbH, Germany) according to the manufacturer's instructions. The experimental procedure has been approved by the university"s ethics committe. Results In 29 of 49 healthy subjects (59.2%) at least one and in 16 persons (35%) all five of the AABs examined were detected above the cut-off. Anti-M3-AABs (61%) and anti-ß2-AABs (59%) were detected most frequently. The mean age of the AAB-positive subjects was 30.9 years (20-55y), with 68.75% being younger than 35 years of age. The COVID-19 history indicated that 62.5% had both recovered and been vaccinated, while 31.25% were vaccinated without ever having experienced confirmed SARS-CoV-2 infection. 6.25% of those testing AAB positive reported being neither vaccinated nor infected with SARS-CoV-2. The gender distribution was: 27 (55%) men, 22 (45%) women. None of the people examined stated to have ever had symptoms of ME/CFS.Conclusion The fact that GPCR-AABs can be detected in a high proportion of healthy individuals suggests that there is no direct causal relationship between AABs and ME/CFS and also raises the question of whether these laboratory findings are indeed clinically relevant. The understanding and significance of the mere detection of AABs as the main indication for immunoadsorption should be seriously reconsidered until causality between them and post-COVID ME/CFS is based on sufficient evidence.Offenlegung Interessenkonflikt: Es bestehen keine Interessenkonflikte.

SARS-CoV-2 vaccination of convalescents boosts neutralization capacity against Omicron subvariants BA.1, BA.2 and BA.5 and can be predicted by anti-S antibody concentrations in serological assays

Background COVID-19 convalescent plasma remains a potential therapy of COVID-19, e.g. for new variants resistant to monoclonal antibodies and for patients with impaired immune response. Significant immune evasion by Omicron has raised concerns that antibody-based therapies may no longer be effective. We assessed whether superimmunized individuals, i.e. vaccinated convalescents, have sufficient cross-neutralization capacity against Omicron to be considered as plasma donors for passive immunotherapy.Methods We report the in-vitro neutralization capacity against SARS-CoV-2 variant B.1 and the Omicron subvariants BA.1, BA.2 and BA.5 of sera from convalescent individuals with and without boost by vaccination. The study included 313 serum samples from 155 individuals with a history of SARS-CoV-2 infection, divided into subgroups without (n=25) and with SARS-CoV-2 vaccination (n=130). We measured anti-SARS-CoV-2 antibody concentrations by serological assays (anti-SARS-CoV-2-QuantiVac-ELISA (IgG) and Elecsys Anti-SARS-CoV-2 S) and neutralizing titers against B.1, BA.1, BA.2 and BA.5 in a pseudovirus neutralization assay.Results Sera of unvaccinated convalescents did not effectively neutralize Omicron sublineages BA.1, BA.2 and BA.5. Neutralizing titers against B.1, BA.1, BA.2 and BA.5 were significantly higher in vaccinated compared to unvaccinated convalescents (p&lt;0.0001) with 52.7-, 210.7-, 141.3- and 105.4-fold higher geometric mean of 50% neutralizing titers in vaccinated compared to unvaccinated convalescents. The increase in neutralizing titers was already achieved by one vaccination dose. Neutralizing titers were highest in the first 3 months after the last immunization event. Concentrations of anti-S antibodies in the anti-SARS-CoV-2-QuantiVac-ELISA (IgG) and Elecsys Anti-SARS-CoV-2 S assays predicted neutralization capacity against B.1 and subvariants.Conclusion These findings confirm substantial immune evasion of the Omicron sublineages, which can be overcome by vaccination of convalescents. This informs strategies for choosing of plasma donors in COVID-19 convalescent plasma programs that shall select specifically vaccinated convalescents with very high titers of anti-S antibodies.Offenlegung Interessenkonflikt: NoneInvited talks abstract/summary

A randomised open-label trial of early, very high-titre convalescent plasma therapy in clinically vulnerable individuals with mild COVID-19 as model of early treatment in a pandemia with a new pathogen: Experience from collection of very high-titer plasma from superimmunized individuals

Background COVID-19 convalescent plasma (CCP) remains a potential therapy of COVID-19. The new CCP trial COVIC-19 takes into account lessons learned from previous trials, including the trial CAPSID, and combines them into a novel approach: - CCP with very high concentrations of SARS-CoV-2 antibodies (≥4,000 BAU/ml) from donors with previous SARS-CoV-2 infection and vaccination - treatment of vulnerable persons early after symptom onset - Sequencing and cross-neutralization analyses to study viral evolution Methods We report the initial experience of collection of very high-titer plasma units for this COVIC-19 trial. We recruited 686 potential donors with previous SARS-CoV-2 infection (inf) and vaccination (vax) who passed initial eligibility check. Anti-SARS-CoV-2 antibody concentrations were measured by anti-SARS-CoV-2 QuantiVac ELISA (Euroimmun) and neutralization capacity was assessed in the GenScript Surrogat neutralization assay and in a pseudovirus neutralization assay. High S-Ab in the QuantiVac assay correlated with high neutralizing capacity.Results The average antibody concentration of those willing to donate was 4,298.58 BAU/ml. S-Ab was ≥4,000 BAU/ml in 41,1% of the individuals and did not significantly differ by gender or ABO type, but were higher among those who had received 3 vax (median 3,746 BAU/ml) or 4 vax (median 4,166 BAU/ml). Highest S-Ab were observed in those with a breakthrough infection after 2 vax, followed by a booster (median 5,159 BAU/ml, 64% ≥4,000 BAU/ml) or breakthrough inf after 3rd or 4th vax (median 3,846; 48% ≥4,000 BAU/ml). 158 qualified individuals ultimately donated CCP with anti-SARS-CoV-2 IgG concentrations ranging from 4,105 BAU/ml to 22,923 BAU/ml with a mean concentration of 8,019 BAU/ml.Conclusion Taking into account all eligibility criteria 31.9 % of the individuals screened could provide plasma units meeting the criteria for high-titer plasma for COVIC-19, however, only 23% actually donated. Collection of very-high titer plasma from super-immunized individuals with previous infection and vaccination is feasible, but requires substantial donor selection and rapid screening and start of apheresis to take advantage of the short period of very high mAb. COVIC-19 is supported by BMBF.Offenlegung Interessenkonflikt: none

Effective neutralizing and cellular immunity against SARS-CoV-2 after mRNA booster vaccination is associated with the activation of B cells and pDCs

Background Recently, we demonstrated that heterologous vaccination regimes against COVID-19, which consisted of a combination of the vector vaccine ChAdOx1 from AstraZeneca and either the mRNA vaccine BNT162b2 from BioNTech or Spikevax from Moderna, resulted in significantly enhanced serological and cellular immune responses against SARS-CoV-2 after second vaccination.Methods In the present follow-up study, we continued to analyze anti-SARS-CoV-2 antibody titers, neutralization capacities against the wildtype virus and the variant of concern (VOC) Omicron BA.1, as well as IFN-g responses against the spike protein up to 6 months after booster vaccination. In addition, applying FACS analysis and cell culture studies using SARS-CoV-2-specific peptides (Novavax), we investigated the potential role of two important antigen-presenting cell types, which circulate in the peripheral blood (plasmacytoid dendritic cells (pDC) and B cells), for the immune response after vaccination.Results One month after booster vaccination, up to 91% of all donors from vaccination regimes containing two or three mRNA doses exhibited detectable Omicron neutralization capacity (Figure 1). Furthermore, we found a stable frequency and expression of antigen-presenting and co-stimulatory molecules on CD19+ B cells up to 3 months after booster vaccination, regardless of the vaccination regime. In pDCs in contrast, we observed a trend for increasing expression of MHC class II and CD40L even after booster vaccination, suggesting an ongoing role in antigen presentation. Performing functional pulsing studies with pDCs and SARS-CoV-2 peptide (Novavax), we demonstrated that pDCs are involved in the presentation of these peptides to T cells (Figure 2).Conclusion In summary, our follow-up study demonstrates that effective neutralizing and cellular immunity against SARS-CoV-2 is associated with the activation of both B cells and pDCs, and that pDCs are functionally involved in antigen presentation after vaccination. Furthermore, our follow-up data up to 6 months after booster vaccination suggests no significant differences in serological and cellular response parameters between vaccination groups, as long as two or three mRNA doses are included.Offenlegung Interessenkonflikt: N/A

SARS-CoV-2 immunity in blood donors during the Omicron BA.5 infection wave – the COVIMBA-study

Background (Re-)Infections of pre-immunized vaccinated or convalescent individuals were the main players in SARS-CoV-2 infection waves with the different omicron strains. There is still a lack of detailed data on how different immunization schemes, exposition risks and antibody tests could predict the probability of (re-)infection. This population-based approach aims to understand the underlying mechanisms of infection and immunization, which is relevant for any future pandemic.Methods To address this issue we selected blood donors who donated blood in June or July 2022 at the beginning of the omicron BA.5 wave. We sent a digital COVID-19 REDCap survey including 170 data fields on SARS-CoV-2 exposure, previous immunizations, and acute infection in the timespan between July and October 2022 to these donors. In close collaboration with data protection supervisors, we thoroughly planned the digital study information and consent forms and permission was granted by the local Ethics committee. Statistical analyses of survey data were performed via &quot;SAS&quot; and &quot;Prism&quot;.Results Of 52.512 blood donors invited for study participation via E-mail, 20% completed the questionnaire. Thus, we recruited a cohort of 10.532 individuals for the investigation of detailed anamnestic data. Analysis revealed that full vaccination with monovalent vaccines significantly reduced infection rates with non-Omicron variants and still had effects on infections with Omicron strains before BA.5 but did not significantly reduce infection rates with the BA.5 strain compared with not fully vaccinated individuals. Carefully partitioned subgroup analysis showed that various combinations of vaccinations and previously experienced infections with different SARS-CoV-2 strains led to significantly varying infections rates during the BA.5 wave.Conclusion REDCap database approach is a suitable method for digital clinical research including anamnestic and serological data. Study concepts based on digital consent forms and questionnaires are convenient for study participants and lead to high response rates. As many countries recently reduced their SARS-CoV-2 surveillance systems and as monitoring does not cover self-testing, digital surveys are a helpful way to capture reliable data on (re-)infection rates keeping evidence up to date.Offenlegung Interessenkonflikt: The authors declare no conflict of interest.

Postersession 3
COVID-19

Appointment

Vorsitz

Topic

Programme

Postersession 3COVID-19

Appointment

Vorsitz

Topic

Programme

Postersession 3
COVID-19