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BackgroundModification of vaccination strategies is needed to improve the immune response to SARS-CoV-2 vaccination in kidney transplant recipients (KTRs). MethodsThis multicenter observational study aimed to determine antibody kinetics among 60 seropositive KTRs and analyzed the effects of the third vaccination against SARS-CoV-2 in 174 previously seronegative KTRs. We investigated whether mycophenolate mofetil (MMF) dose reduction by 25-50% prior the third vaccination influences vaccination success. Results18 of 60 (30%) seropositive KTRs became seronegative in the serological assay within six months. Loss of antibodies was predicted by low initial antibody levels ([≤]206.8 BAU/ml), older age, and impaired graft function. A third vaccination in previously seronegative KTRs induced seroconversion in 56 of 174 (32.1%) KTRs with median antibody levels 119 (76-353) BAU/ml and median neutralizing capacity titer of 1:10 (0- 1:40). Multivariate logistic regression revealed that initial antibody levels (OR 1.39, 95% CI 1.09-1.76), graft function (OR 0.05, 95% CI 0.01-0.39), time after transplantation (OR 1.04, 95% CI 1.02-1.07) and MMF trough levels (OR 0.43, 95% CI 0.21-0.88) correlated with seroconversion, p<0.05. After controlling for these confounders, the effect of MMF dose reduction was calculated using propensity score matching. KTRs in the MMF reduction group had significantly lower MMF serum concentrations prior to the third vaccination and were more likely to develop antibody levels [≥]35.2 BAU/ml than their matched KTRs (p=0.02). ConclusionsTemporary reduction in MMF dose might be a promising approach to improve the immune response in KTRs.
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BackgroundThe role of pre-school children as a source and distributor of SARS-CoV-2 infections is still unclear. Daycare facilities that care particularly for young children with limited hygiene measures may contribute to the infection dynamics during the pandemic. The aim of this study was to implement and evaluate a voluntary SARS-CoV-2 screening program in daycare facilities. MethodsThe study was conducted over a period of 4 weeks, from June 10th to July 7th 2020. The aim was to screen a representative group of 5000 individuals (children and staff at a ratio 3:1) attending daycare facilities in Dusseldorf, North Rhine-Westphalia. Tests were performed twice per week with oral rinsing water as sample material for the detection of SARS-CoV-2-RNA by molecular pool testing. ResultsA total number of 5210 participants (75.9% children and 24.1% staff) from 115 day care centers participated in the study. Of a total of 34,068 returned samples (81.7%) during the study period, only one SARS-CoV-2 infection of a child was detected in the study cohort with one likely secondary infection within the daycare facility. Of note, during the study phase, no increase of SARS- CoV-2 infections was observed in daycare center compared to the overall incidence in Dusseldorf. ConclusionsA voluntary screening program for SARS-CoV-2 infections could successfully be implemented in daycare facilities. Although the low overall incidence during the study period precludes firm conclusions, there was no evidence for increased transmission in children attending daycare facilities compared to the general population of Dusseldorf. SummarySARS-CoV-2 screening programs in daycare facilities may help to detect asymptomatic infections at an early stage and thereby support containment. Here, a large screening study was evaluated suggesting similar infection rates in daycare facilities compared to the general population.
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The determination of anti-SARS-CoV-2 neutralizing antibodies (NAbs) is of interest in many respects. High NAb titers, for example, are the most important criterion regarding the effectiveness of convalescent plasma therapy. However, common cell culture-based NAb assays are time-consuming and feasible only in special laboratories. Our data reveal the suitability of a novel ELISA-based surrogate virus neutralization test (sVNT) to easily measure the inhibition-capability of NAbs in the plasma of COVID-19 convalescents. We propose a combined strategy to detect plasma samples with high NAb titers ([≥] 1:160) reliably and to, simultaneously, reduce the risk of erroneously identifying low-titer specimens. For this approach, results of the sVNT assay are compared to and combined with those acquired from the Euroimmun anti-SARS-CoV-2 IgG assay. Both assays are appropriate for high-throughput screening in standard BSL-2 laboratories. Our measurements further show a long-lasting humoral immunity of at least 11 months after symptom onset.
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During the SARS-CoV-2 outbreak, several epidemiological measures, such as cumulative case-counts, incidence rates, effective reproduction numbers and doubling times, have been used to inform the general public and to justify interventions such as lockdown. During the course of the epidemic, it has been very likely that not all infectious people have been identified, which lead to incomplete case-detection. Apart from asymptomatic infections, possible reasons for incomplete case-detection are availability of test kits and changes in test policies during the course of the epidemic. So far, it has not been examined how biased the reported epidemiological measures are in the presence of incomplete case detection. In this work, we assess the four frequently used measures with respect to incomplete case-detection: 1) cumulative case-count, 2) incidence rate, 3) effective reproduction number and 4) doubling time. We apply an age-structured SIR model to simulate a SARS-CoV-2 outbreak followed by a lockdown in a hypothetical population. Different scenarios about temporal variations in case-detection are applied to the four measures during outbreak and lockdown. The biases resulting from incomplete case-detection on the four measures are compared. It turns out that the most frequently used epidemiological measure, the cumulative case count is most prone to bias in all of our settings. The effective reproduction number is the least biased measure. With a view to future reporting about this or other epidemics, we recommend to use of the effective reproduction number for informing the general public and policy makers.
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The coronavirus disease 2019 (COVID-19) pandemic caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) affects millions of people and killed hundred-thousands of individuals. While acute and intermediate interactions between SARS-CoV-2 and the immune system have been studied extensively, long-term impacts on the cellular immune system remained to be analyzed. Here, we comprehensively characterized immunological changes in peripheral blood mononuclear cells in 49 COVID-19 convalescent individuals (CI) in comparison to 27 matched SARS-CoV-2 unexposed individuals (UI). Despite recovery from the disease for more than 2 months, CI showed significant decreases in frequencies of invariant NKT and NKT-like cells compared to UI. Concomitant with the decrease in NKT-like cells, an increase in the percentage of Annexin V and 7-AAD double positive NKT-like cells was detected, suggesting that the reduction in NKT-like cells results from cell death months after recovery. Significant increases in regulatory T cell frequencies, TIM-3 expression on CD4 and CD8 T cells, as well as PD-L1 expression on B cells were also observed in CI, while the cytotoxic potential of T cells and NKT-like cells, defined by GzmB expression, was significantly diminished. However, both CD4 and CD8 T cells of CI showed increased Ki67 expression and were fully capable to proliferate and produce effector cytokines upon TCR stimulation. Collectively, we provide the first comprehensive characterization of immune signatures in patients recovering from SARS-CoV-2 infection, suggesting that the cellular immune system of COVID-19 patients is still under a sustained influence even months after the recovery from disease.
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We analysed SARS-CoV-2 specific antibody responses in 42 social and working contacts of a super-spreader from the Heinsberg area in Germany. Consistent with a high-prevalence setting 26 individuals had SARS-CoV-2 antibodies determined by in-house neutralisation testing. These results were compared with four commercial assays, suggesting limited sensitivity of the assays in such a high-prevalence setting. Although SARS-CoV-2 nucleocapsid-restricted tests showed a better sensitivity, spike-based assays had a stronger correlation with neutralisation capacity.
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COVID-19 pandemic caused by SARS-CoV-2 infection is a public health emergency. COVID-19 typically exhibits respiratory illness. Unexpectedly, emerging clinical reports indicate that neurological symptoms continue to rise, suggesting detrimental effects of SARS-CoV-2 on the central nervous system (CNS). Here, we show that a Dusseldorf isolate of SARS-CoV-2 enters 3D human brain organoids within two days of exposure. Using COVID-19 convalescent serum, we identified that SARS-CoV-2 preferably targets soma of cortical neurons but not neural stem cells, the target cell type of ZIKA virus. Imaging cortical neurons of organoids reveal that SARS-CoV-2 exposure is associated with missorted Tau from axons to soma, hyperphosphorylation, and apparent neuronal death. Surprisingly, SARS-CoV-2 co-localizes specifically with Tau phosphorylated at Threonine-231 in the soma, indicative of early neurodegeneration-like effects. Our studies, therefore, provide initial insights into the impact of SARS-CoV-2 as a neurotropic virus and emphasize that brain organoids could model CNS pathologies of COVID-19. One sentence summaryCOVID-19 modeling in human brain organoids
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Oral swabs, sputum and blood samples from 18 patients with SARS-CoV-2 infection were examined using real-time reverse transcription polymerase chain reaction (RT-PCR) testing. Whereas oral swabs or sputum from the lower respiratory tract were tested RT-PCR positive in all patients, RNAemia was neither detected in 3 patients without symptoms nor in 14 patients with flu-like symptoms, fever or pneumonia. The only patient with RNAemia suffered from acute respiratory distress syndrome (ARDS) and was artificially ventilated in an intensive care unit. Risk for SARS-CoV-2 transmission through blood components in asymptomatic SARS-CoV-2 infected individuals therefore seems negligible but further studies are needed.
