SARS-CoV-2 serology in MIS-C

Abstract

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.

SOURCE: Pediatrics

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How different masks work

Excerpt

Which mask works best? To visualise droplets and aerosols, UNSW researchers used LED lighting system & a high-speed camera, filming people coughing and sneezing in different scenarios — using no mask, two different types of cloth masks, and a surgical mask.

We confirmed that even speaking generates substantial droplets. Coughing and sneezing (in that order) generate even more. A three-ply surgical mask was significantly better than a one-layered cloth mask at reducing droplet emissions caused by speaking, coughing and sneezing, followed by a double-layer cloth face covering. A single-layer cloth face covering also reduced the droplet spread caused by speaking, coughing and sneezing but was not as good as a two-layered cloth mask or surgical mask.

We do not know how this translates to infection risk, which will depend on how many asymptomatic or mildly symptomatic infected people are around. However, it shows a single layer is not as good a barrier as a double layer.

MORE: UNSW

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