Objectives. We aimed to measure SARS-CoV-2 serologic responses in children hospitalized with multisystem inflammatory syndrome (MIS-C) compared to COVID-19, Kawasaki Disease (KD) and hospitalized pediatric controls.
Methods. From March 17, 2020 – May 26, 2020, we prospectively identified hospitalized children at Children’s Healthcare of Atlanta with MIS-C (n=10), symptomatic COVID-19 (n=10), KD (n=5), and hospitalized controls (n=4). With IRB approval, we obtained prospective and residual blood samples from these children and measured SARS-CoV-2 spike receptor binding domain (RBD) IgM and IgG, full-length spike IgG, and nucleocapsid protein antibodies by quantitative ELISAs and SARS-CoV-2 neutralizing antibodies by live-virus focus reduction neutralization assays. We statistically compared the log-transformed antibody titers among groups and performed linear regression analyses.
Results. All children with MIS-C had high titers of SARS-CoV-2 RBD IgG antibodies, which correlated with full-length spike IgG antibodies (R2 =0.956, P<0.001), nucleocapsid protein antibodies (R2 =0.846,P<0.001), and neutralizing antibodies (R2 =0.667, P<0.001). Children with MIS-C had significantly higher SARS-CoV-2 RBD IgG antibody titers (geometric mean titer [GMT] 6800, 95% CI 3495-13231) than children with COVID-19 (GMT 626, 95% CI 251-1563, P<0.001), KD (GMT 124, 95% CI 91-170, P<0.001) and hospitalized controls (GMT 85, P<0.001). All children with MIS-C also had detectable RBD IgM antibodies, indicating recent SARS-CoV-2 infection. RBD IgG titers correlated with erythrocyte sedimentation rate (R2 =0.512, P<0.046) and with hospital (R2 =0.548, P=0.014) and ICU lengths of stay (R2 =0.590, P=0.010).
Conclusion. 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.
The Fulgent COVID-19 IgM/IgG DR Test is a solid phase immunochromatographic assay for the rapid, qualitative, and differential detection of human IgG and IgM antibodies against SARS-Cov-2 from whole blood, plasma, or serum samples.
The presence of these antibodies is indicative of an adaptive immune response to COVID-19, indicating recent or prior infection. The test uses anti-human IgM and IgG antibodies immobilized on separate nitrocellulose membrane strips to capture and detect antibodies against COVID-19 antigens. IgM antibodies are produced during the early phase of infection (first few days), whereas IgG antibodies are typically detectable during the active, late, and recovery phase of infection (7-10 days post-infection). Fulgent’s Antibody Test screens for both markers to maximize the detection of antibodies against SARS-CoV-2.
* This test has not been cleared or approved by the FDA. Fulgent’s laboratory is regulated under CLIA and is qualified to perform high-complexity testing for investigational or research purposes. This test should not be used as a diagnostic test. Since systematic and technical factors can affect the accuracy of testing, the results of testing should always be interpreted in the context of clinical and familial data.
Whole blood, plasma, or serum sample
Test results will be reported as positive, negative, or indeterminate
The option to retest if indeterminate is available
Results are typically available within 1-2 days of your sample being received by the lab.
We review aspects of the antibody response to SARS-CoV-2, the causative agent of the COVID-19 pandemic. The topics we cover are relevant to immunotherapy with plasma from recovered patients, monoclonal antibodies against the viral S-protein, and soluble forms of the receptor for the virus, angiotensin converting enzyme 2. The development of vaccines against SARS-CoV-2, an essential public health tool, will also be informed by an understanding of the antibody response in infected patients. Although virus-neutralizing antibodies are likely to protect, antibodies could potentially trigger immunopathogenic events in SARS-CoV-2-infected patients or enhance infection. An awareness of these possibilities may benefit clinicians and the developers of antibody-based therapies and vaccines.