Quantitative SARS-CoV-2 Serology in Children With Multisystem Inflammatory Syndrome (MIS-C).

We aimed to measure severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) serological responses in children hospitalized with multisystem inflammatory syndrome in children (MIS-C) compared with those with coronavirus disease 2019 (COVID-19), those with Kawasaki disease (KD), and hospitalized pediatric controls. From March 17, 2020, to May 26, 2020, we prospectively identified hospitalized children with MIS-C (n = 10), symptomatic COVID-19 (n = 10), and KD (n = 5) and hospitalized controls (n = 4) at Children's Healthcare of Atlanta. With institutional review board approval, we obtained prospective and residual blood samples from these children and measured SARS-CoV-2 spike receptor-binding domain (RBD) immunoglobulin M and immunoglobulin G (IgG), full-length spike IgG, and nucleocapsid protein antibodies using quantitative enzyme-linked immunosorbent assays and SARS-CoV-2 neutralizing antibodies using live-virus focus-reduction neutralization assays. We statistically compared the log-transformed antibody titers among groups and performed linear regression analyses. All children with MIS-C had high titers of SARS-CoV-2 RBD IgG antibodies, which correlated with full-length spike IgG antibodies (R 2 = 0.956; P < .001), nucleocapsid protein antibodies (R 2 = 0.846; P < .001), and neutralizing antibodies (R 2 = 0.667; P < .001). Children with MIS-C had significantly higher SARS-CoV-2 RBD IgG antibody titers (geometric mean titer 6800; 95% confidence interval 3495-13 231) than children with COVID-19 (geometric mean titer 626; 95% confidence interval 251-1563; P < .001), children with KD (geometric mean titer 124; 95% confidence interval 91-170; P < .001), and hospitalized controls (geometric mean titer 85; P < .001). All children with MIS-C also had detectable RBD immunoglobulin M antibodies, indicating recent SARS-CoV-2 infection. RBD IgG titers correlated with the erythrocyte sedimentation rate (R 2 = 0.512; P < .046) and with hospital (R 2 = 0.548; P = .014) and ICU lengths of stay (R 2 = 0.590; P = .010). Quantitative SARS-CoV-2 serology may have a role in establishing the diagnosis of MIS-C, distinguishing it from similar clinical entities, and stratifying risk for adverse outcomes.

Rostad CA ，Chahroudi A ，Mantus G ，Lapp SA ，Teherani M ，Macoy L ，Tarquinio KM ，Basu RK ，Kao C ，Linam WM ，Zimmerman MG ，Shi PY ，Menachery VD ，Oster ME ，Edupuganti S ，Anderson EJ ，Suthar MS ，Wrammert J ，Jaggi P ... -  《-》

Dynamic changes in anti-SARS-CoV-2 antibodies during SARS-CoV-2 infection and recovery from COVID-19.

Li K ，Huang B ，Wu M ，Zhong A ，Li L ，Cai Y ，Wang Z ，Wu L ，Zhu M ，Li J ，Wang Z ，Wu W ，Li W ，Bosco B ，Gan Z ，Qiao Q ，Wu J ，Wang Q ，Wang S ，Xia X ... -  《Nature Communications》

Pediatric evaluation of clinical specificity and sensitivity of SARS-CoV-2 IgG and IgM serology assays.

Bohn MK ，Hall A ，Wilson S ，Taher J ，Sepiashvili L ，Adeli K ... -  《-》

A Combination of N and S Antigens With IgA and IgG Measurement Strengthens the Accuracy of SARS-CoV-2 Serodiagnostics.

Primary diagnosis of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection is based on detection of virus RNA in nasopharyngeal swab samples. In addition, analysis of humoral immunity against SARS-CoV-2 has an important role in viral diagnostics and seroprevalence estimates. We developed and optimized an enzyme immunoassays (EIA) using SARS-CoV-2 nucleoprotein (N), S1 and receptor binding domain (RBD) of the viral spike protein, and N proteins from SARS, Middle East respiratory syndrome (MERS), and 4 low-pathogenic human CoVs. Neutralizing antibody activity was compared with SARS-CoV-2 IgG, IgA, and IgM EIA results. The sensitivity of EIA for detecting immune response in COVID-19 patients (n = 101) was 77% in the acute phase and 100% in the convalescent phase of SARS-CoV-2 infection when N and RBD were used as antigens in IgG and IgA specific EIAs. SARS-CoV-2 infection significantly increased humoral immune responses against the 229E and NL63 N proteins. S1 and RBD-based EIA results had a strong correlation with microneutralization test results. The data indicate a combination of SARS-CoV-2 S1 or RBD and N proteins and analysis of IgG and IgA immunoglobulin classes in sera provide an excellent basis for specific and sensitive serological diagnostics of COVID-19.

Jalkanen P ，Pasternack A ，Maljanen S ，Melén K ，Kolehmainen P ，Huttunen M ，Lundberg R ，Tripathi L ，Khan H ，Ritvos MA ，Naves R ，Haveri A ，Österlund P ，Kuivanen S ，Jääskeläinen AJ ，Kurkela S ，Lappalainen M ，Rantasärkkä K ，Vuorinen T ，Hytönen J ，Waris M ，Tauriainen S ，Ritvos O ，Kakkola L ，Julkunen I ... -  《-》

Comparison of 2 fully automated tests detecting antibodies against nucleocapsid N and spike S1/S2 proteins in COVID-19.

Automated assays for detecting severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) antibodies in coronavirus disease 2019 (COVID-19) diagnostics have recently come available. We compared the performance of the Elecsys® Anti-SARS-CoV-2 and LIAISON® SARS-CoV-2 S1/S2 IgG tests. The seroconversion panel comprised of 120 samples from 13 hospitalized COVID-19 patients. For the sensitivity and specificity testing, samples from COVID-19 outpatients >15 days after positive nucleic acid amplification test (NAAT) result (n = 35) and serum control samples collected before the COVID-19 era (n = 161) were included in the material. Samples for the detection of possible cross-reactions were also tested. Based on our results, the SARS-CoV-2 antibodies can be quite reliably detected 2 weeks after NAAT positivity and 3 weeks after the symptom onset with both tests. However, since some COVID-19 patients were positive only with Elecsys®, the antibodies should be screened against N-antigen (Elecsys®) and reactive samples confirmed with S antigen (LIAISON®), but both results should be reported. In some COVID-19 patients, the serology can remain negative.

Flinck H ，Rauhio A ，Luukinen B ，Lehtimäki T ，Haapala AM ，Seiskari T ，Aittoniemi J ... -  《-》