Cardiac complications in children with acute COVID-19 vs multisystem inflammatory syndrome in children (MIS-C).

BACKGROUND: Cardiac involvement can lead to significant morbidity in children with acute COVID-19 or multisystem inflammatory syndrome in children (MIS-C). However, the presentation and outcomes of cardiac involvement may differ among these 2 conditions. We aimed to compare the frequency and extent of cardiac involvement among children admitted with acute COVID-19 vs those with MIS-C. METHODS: We conducted a cross sectional study of patients admitted to our hospital from March 2020 to August 2021 with symptomatic acute COVID-19 or MIS-C. Cardiac involvement was defined by presence of 1 or more of the following: elevated troponin, elevated brain natriuretic peptide, reduced left ventricular ejection fraction on echocardiogram, coronary dilation on echocardiogram, or abnormal electrocardiogram reading. RESULTS: Among 346 acute COVID-19 patients with median age of 8.9 years and 304 MIS-C patients with median age of 9.1 years, cardiac involvement was present in 33 acute COVID-19 patients (9.5%) and 253 MIS-C patients (83.2%). The most common cardiac abnormality was abnormal electrocardiogram in acute COVID-19 patients (7.5%) and elevated troponin in MIS-C patients (67.8%). Among acute COVID-19 patients, obesity was significantly associated with cardiac involvement. Among MIS-C patients, non-Hispanic Black race/ethnicity was significantly associated with cardiac involvement. CONCLUSIONS: Cardiac involvement is much more common in children with MIS-C than in those with acute COVID-19. These results reinforce our standardized practice of performing full cardiac evaluations and follow-up in all patients with MIS-C but only in acute COVID-19 patients with signs or symptoms of cardiac involvement.

Six-month cardiac outcomes in children with multisystem inflammatory syndrome in children.

BACKGROUND: Multisystem inflammatory syndrome in children is a rare, post-infectious complication of SARS-CoV-2 infection in children. We aimed to assess the long-term sequelae, particularly cardiac, in a large, diverse population. METHODS: We performed a retrospective cohort study of all children (aged 0-20 years, n = 304) admitted to a tertiary care centre with a diagnosis of multisystem inflammatory syndrome in children from March 1, 2020 to August 31, 2021 and had at least one follow-up visit through December 31, 2021. Data were collected at hospitalisation, 2 weeks, 6 weeks, 3 months, and 1 year after diagnosis, where applicable. Cardiovascular outcomes included left ventricular ejection fraction, presence or absence of pericardial effusion, coronary artery abnormalities, and abnormal electrocardiogram findings. RESULTS: Population was median age 9 years (IQR 5-12), 62.2% male, 61.8% African American (AA), and 15.8% Hispanic. Hospitalisation findings included abnormal echocardiogram 57.2%, mean worst recorded left ventricular ejection fraction 52.4% ± 12.4%, non-trivial pericardial effusion 13.4%, coronary artery abnormalities 10.6%, and abnormal ECG 19.6%. During follow-up, abnormal echocardiogram significantly decreased to 6.0% at 2 weeks and 4.7% at 6 weeks. Mean left ventricular ejection fraction significantly increased to 65.4% ± 5.6% at 2 weeks and stabilised. Pericardial effusion significantly decreased to 3.2% at 2 weeks and stabilised. Coronary artery abnormalities significantly decreased to 2.0% and abnormal electrocardiograms significantly decreased to 6.4% at 2 weeks and stabilised. CONCLUSION: Children with multisystem inflammatory syndrome in children have significant echocardiographic abnormalities during the acute presentation, but these findings typically improve within weeks. However, a small subset of patients may have persistent coronary abnormalities.

Epidemiological and Clinical Features of Kawasaki Disease During the COVID-19 Pandemic in the United States.

Importance: Public health measures implemented during the COVID-19 pandemic had widespread effects on population behaviors, transmission of infectious diseases, and exposures to environmental pollutants. This provided an opportunity to study how these factors potentially influenced the incidence of Kawasaki disease (KD), a self-limited pediatric vasculitis of unknown etiology. Objectives: To examine the change in KD incidence across the United States and evaluate whether public health measures affected the prevalence of KD. Design, Setting, and Participants: This multicenter cohort study included consecutive, unselected patients with KD who were diagnosed between January 1, 2018, and December 31, 2020 (multicenter cohort with 28 pediatric centers), and a detailed analysis of patients with KD who were diagnosed between January 1, 2002, and November 15, 2021 (Rady Children's Hospital San Diego [RCHSD]). Main Outcomes and Measures: For the multicenter cohort, the date of fever onset for each patient with KD was collected. For RCHSD, detailed demographic and clinical data as well as publicly available, anonymized mobile phone data and median household income by census block group were collected. The study hypothesis was that public health measures undertaken during the pandemic would reduce exposure to the airborne trigger(s) of KD and that communities with high shelter-in-place compliance would experience the greatest decrease in KD incidence. Results: A total of 2461 KD cases were included in the multicenter study (2018: 894; 2019: 905; 2020: 646), and 1461 cases (median [IQR] age, 2.8 years [1.4-4.9 years]; 900 [61.6%] males; 220 [15.1%] Asian, 512 [35.0%] Hispanic, and 338 [23.1%] White children) from RCHSD between 2002 and 2021 were also included. The 28.2% decline in KD cases nationally during 2020 (646 cases) compared with 2018 (894 cases) and 2019 (905 cases) was uneven across the United States. For RCHSD, there was a disproportionate decline in KD cases in 2020 to 2021 compared with the mean (SD) number of cases in earlier years for children aged 1 to 5 years (22 vs 44.9 [9.9]; P = .02), male children (21 vs 47.6 [10.0]; P = .01), and Asian children (4 vs 11.8 [4.4]; P = .046). Mobility data did not suggest that shelter-in-place measures were associated with the number of KD cases. Clinical features including strawberry tongue, enlarged cervical lymph node, and subacute periungual desquamation were decreased during 2020 compared with the baseline period (strawberry tongue: 39% vs 63%; P = .04; enlarged lymph node: 21% vs 32%; P = .09; periungual desquamation: 47% vs 58%; P = .16). School closures, masking mandates, decreased ambient pollution, and decreased circulation of respiratory viruses all overlapped to different extents with the period of decreased KD cases. KD in San Diego rebounded in the spring of 2021, coincident with lifting of mask mandates. Conclusions and Relevance: In this study of epidemiological and clinical features of KD during the COVID-19 pandemic in the United States, KD cases fell and remained low during the period of masking and school closure. Mobility data indicated that differential intensity of sheltering in place was not associated with KD incidence. These findings suggest that social behavior is associated with exposure to the agent(s) that trigger KD and are consistent with a respiratory portal of entry for the agent(s).

Distinguishing immune activation and inflammatory signatures of multisystem inflammatory syndrome in children (MIS-C) versus hemophagocytic lymphohistiocytosis (HLH).

BACKGROUND: Multisystem inflammatory syndrome in children (MIS-C) is a potentially life-threatening sequela of severe acute respiratory syndrome coronavirus 2 infection characterized by hyperinflammation and multiorgan dysfunction. Although hyperinflammation is a prominent manifestation of MIS-C, there is limited understanding of how the inflammatory state of MIS-C differs from that of well-characterized hyperinflammatory syndromes such as hemophagocytic lymphohistiocytosis (HLH). OBJECTIVES: We sought to compare the qualitative and quantitative inflammatory profile differences between patients with MIS-C, coronavirus disease 2019, and HLH. METHODS: Clinical data abstraction from patient charts, T-cell immunophenotyping, and multiplex cytokine and chemokine profiling were performed for patients with MIS-C, patients with coronavirus disease 2019, and patients with HLH. RESULTS: We found that both patients with MIS-C and patients with HLH showed robust T-cell activation, markers of senescence, and exhaustion along with elevated TH1 and proinflammatory cytokines such as IFN-γ, C-X-C motif chemokine ligand 9, and C-X-C motif chemokine ligand 10. In comparison, the amplitude of T-cell activation and the levels of cytokines/chemokines were higher in patients with HLH when compared with patients with MIS-C. Distinguishing inflammatory features of MIS-C included elevation in TH2 inflammatory cytokines such as IL-4 and IL-13 and cytokine mediators of angiogenesis, vascular injury, and tissue repair such as vascular endothelial growth factor A and platelet-derived growth factor. Immune activation and hypercytokinemia in MIS-C resolved at follow-up. In addition, when these immune parameters were correlated with clinical parameters, CD8+ T-cell activation correlated with cardiac dysfunction parameters such as B-type natriuretic peptide and troponin and inversely correlated with platelet count. CONCLUSIONS: Overall, this study characterizes unique and overlapping immunologic features that help to define the hyperinflammation associated with MIS-C versus HLH.

Serologic and Cytokine Signatures in Children With Multisystem Inflammatory Syndrome and Coronavirus Disease 2019.

BACKGROUND: The serologic and cytokine responses of children hospitalized with multisystem inflammatory syndrome (MIS-C) vs coronavirus disease 2019 (COVID-19) are poorly understood. METHODS: We performed a prospective, multicenter, cross-sectional study of hospitalized children who met the Centers for Disease Control and Prevention case definition for MIS-C (n = 118), acute COVID-19 (n = 88), or contemporaneous healthy controls (n = 24). We measured severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) spike receptor-binding domain (RBD) immunoglobulin G (IgG) titers and cytokine concentrations in patients and performed multivariable analysis to determine cytokine signatures associated with MIS-C. We also measured nucleocapsid IgG and convalescent RBD IgG in subsets of patients. RESULTS: Children with MIS-C had significantly higher SARS-CoV-2 RBD IgG than children with acute COVID-19 (median, 2783 vs 146; P < .001), and titers correlated with nucleocapsid IgG. For patients with MIS-C, RBD IgG titers declined in convalescence (median, 2783 vs 1135; P = .010) in contrast to patients with COVID-19 (median, 146 vs 4795; P < .001). MIS-C was characterized by transient acute proinflammatory hypercytokinemia, including elevated levels of interleukin (IL) 6, IL-10, IL-17A, and interferon gamma (IFN-γ). Elevation of at least 3 of these cytokines was associated with significantly increased prevalence of prolonged hospitalization ≥8 days (prevalence ratio, 3.29 [95% CI, 1.17-9.23]). CONCLUSIONS: MIS-C was associated with high titers of SARS-CoV-2 RBD IgG antibodies and acute hypercytokinemia with IL-6, IL-10, IL-17A, and IFN-γ.

Giant Coronary Aneurysms in Multisystem Inflammatory Syndrome in Children Associated With SARS-CoV-2 Infection.

Multisystem inflammatory syndrome in children (MIS-C) can cause a myriad of cardiac manifestations, including coronary dilation and aneurysms; giant aneurysms are infrequent. We describe 3patients with giant coronary aneurysms associated with MIS-C, including the youngest case reported to date, treated with intravenous immunoglobulin, corticosteroids, and biologic agents. (Level of Difficulty: Intermediate.).

Intent to Vaccinate SARS-CoV-2 Infected Children in US Households: A Survey.

A paucity of data exists evaluating a guardian's intent to vaccinate their child against COVID-19 in the United States. We administered 102 first (April-November 2020) and 45 second (December-January 2020-2021) surveys to guardians of children (<18 years) who had a laboratory-confirmed diagnosis of COVID-19 and assessed their intent to give a COVID-19 vaccine to their child, when one becomes available. The first and second surveys of the same cohort of guardians were conducted before and following the press releases detailing the adult Pfizer-BioNTech and Moderna Phase 3 results. Both surveys included an intent-to-vaccinate question using the subjective language of "if a safe and effective vaccine" became available, and a second question was added to second surveys using the objective language of "would prevent 19 of 20 people from getting disease". When using subjective language, 24 of 45 (53%) guardians endorsed vaccine administration for their children in the first survey, which decreased to 21 (46%) in the second survey. When adding objective language, acceptance of vaccination increased to 31 (69%, p = 0.03). Common reasons for declining vaccination were concerns about adverse effects and/or vaccine safety. Providing additional facts on vaccine efficacy increased vaccine acceptance. Evidence-based strategies are needed to increase pediatric COVID-19 vaccine uptake.

Multisystem Inflammatory Syndrome in Children: Survey of Protocols for Early Hospital Evaluation and Management.

OBJECTIVE: To describe the similarities and differences in the evaluation and treatment of multisystem inflammatory syndrome in children (MIS-C) at hospitals in the US. STUDY DESIGN: We conducted a cross-sectional survey from June 16 to July 16, 2020, of US children's hospitals regarding protocols for management of patients with MIS-C. Elements included characteristics of the hospital, clinical definition of MIS-C, evaluation, treatment, and follow-up. We summarized key findings and compared results from centers in which >5 patients had been treated vs those in which ≤5 patients had been treated. RESULTS: In all, 40 centers of varying size and experience with MIS-C participated in this protocol survey. Overall, 21 of 40 centers required only 1 day of fever for MIS-C to be considered. In the evaluation of patients, there was often a tiered approach. Intravenous immunoglobulin was the most widely recommended medication to treat MIS-C (98% of centers). Corticosteroids were listed in 93% of protocols primarily for moderate or severe cases. Aspirin was commonly recommended for mild cases, whereas heparin or low molecular weight heparin were to be used primarily in severe cases. In severe cases, anakinra and vasopressors frequently were recommended; 39 of 40 centers recommended follow-up with cardiology. There were similar findings between centers in which >5 patients vs ≤5 patients had been managed. Supplemental materials containing hospital protocols are provided. CONCLUSIONS: There are many similarities yet key differences between hospital protocols for MIS-C. These findings can help healthcare providers learn from others regarding options for managing MIS-C.

Symptomatic Acute Myocarditis in 7 Adolescents After Pfizer-BioNTech COVID-19 Vaccination.

Trials of coronavirus disease 2019 (COVID-19) vaccination included limited numbers of children, so they may not have detected rare but important adverse events in this population. We report 7 cases of acute myocarditis or myopericarditis in healthy male adolescents who presented with chest pain all within 4 days after the second dose of Pfizer-BioNTech COVID-19 vaccination. Five patients had fever around the time of presentation. Acute COVID-19 was ruled out in all 7 cases on the basis of negative severe acute respiratory syndrome coronavirus 2 real-time reverse transcription polymerase chain reaction test results of specimens obtained by using nasopharyngeal swabs. None of the patients met criteria for multisystem inflammatory syndrome in children. Six of the 7 patients had negative severe acute respiratory syndrome coronavirus 2 nucleocapsid antibody assay results, suggesting no previous infection. All patients had an elevated troponin. Cardiac MRI revealed late gadolinium enhancement characteristic of myocarditis. All 7 patients resolved their symptoms rapidly. Three patients were treated with nonsteroidal antiinflammatory drugs only, and 4 received intravenous immunoglobulin and corticosteroids. In this report, we provide a summary of each adolescent's clinical course and evaluation. No causal relationship between vaccine administration and myocarditis has been established. Continued monitoring and reporting to the US Food and Drug Administration Vaccine Adverse Event Reporting System is strongly recommended.

Secretory phospholipase A2 in SARS-CoV-2 infection and multisystem inflammatory syndrome in children (MIS-C).

Secretory phospholipase 2 (sPLA2) acts as a mediator between proximal and distal events of the inflammatory cascade. Its role in SARS-CoV-2 infection is unknown, but could contribute to COVID-19 inflammasome activation and cellular damage. We present the first report of plasma sPLA2 levels in adults and children with COVID-19 compared with controls. Currently asymptomatic adults with a history of recent COVID-19 infection (≥4 weeks before) identified by SARS-CoV-2 IgG antibodies had sPLA2 levels similar to those who were seronegative (9 ± 6 vs.17 ± 28 ng/mL, P = 0.26). In contrast, children hospitalized with severe COVID-19 had significantly elevated sPLA2 compared with those with mild or asymptomatic SARS-CoV-2 infection (269 ± 137 vs. 2 ± 3 ng/mL, P = 0.01). Among children hospitalized with multisystem inflammatory syndrome in children (MIS-C), all had severe disease requiring pediatric intensive care unit (PICU) admission. sPLA2 levels were significantly higher in those with acute illness <10 days versus convalescent disease ≥10 days (540 ± 510 vs. 2 ± 1, P = 0.04). Thus, sPLA2 levels correlated with COVID-19 severity and acute MIS-C in children, implicating a role in inflammasome activation and disease pathogenesis. sPLA2 may be a useful biomarker to stratify risk and guide patient management for children with acute COVID-19 and MIS-C. Therapeutic compounds targeting sPLA2 and inflammasome activation warrant consideration.

Retropharyngeal Edema and Neck Pain in Multisystem Inflammatory Syndrome in Children (MIS-c).

We defined the prevalence of neck pain, trismus, or dysphagia (28.4%) and retropharyngeal edema (2.9%) among 137 patients with multisystem inflammatory syndrome in children (MIS-c). Retropharyngeal edema or phlegmon has been documented radiologically in at least 9 children. Symptoms of neck inflammation are common in MIS-c.

Altered amino acid profile in patients with SARS-CoV-2 infection.

Low plasma arginine bioavailability has been implicated in endothelial dysfunction and immune dysregulation. The role of arginine in COVID-19 is unknown, but could contribute to cellular damage if low. Our objective was to determine arginine bioavailability in adults and children with COVID-19 vs. healthy controls. We hypothesized that arginine bioavailability would be low in patients with COVID-19 and multisystem inflammatory syndrome in children (MIS-C). We conducted a prospective observational study of three patient cohorts; arginine bioavailability was determined in asymptomatic healthy controls, adults hospitalized with COVID-19, and hospitalized children/adolescents <21 y old with COVID-19, MIS-C, or asymptomatic severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection identified on admission screen. Mean patient plasma amino acids were compared to controls using the Student's t test. Arginine-to-ornithine ratio, a biomarker of arginase activity, and global arginine bioavailability ratio (GABR, arginine/[ornithine+citrulline]) were assessed in all three groups. A total of 80 patients were included (28 controls, 32 adults with COVID-19, and 20 pediatric patients with COVID-19/MIS-C). Mean plasma arginine and arginine bioavailability ratios were lower among adult and pediatric patients with COVID-19/MIS-C compared to controls. There was no difference between arginine bioavailability in children with COVID-19 vs. MIS-C. Adults and children with COVID-19 and MIS-C in our cohort had low arginine bioavailability compared to healthy adult controls. This may contribute to immune dysregulation and endothelial dysfunction in COVID-19. Low arginine-to-ornithine ratio in patients with COVID-19 or MIS-C suggests an elevation of arginase activity. Further study is merited to explore the role of arginine dysregulation in COVID-19.

Multisystem Inflammatory Syndrome in U.S. Children and Adolescents.

BACKGROUND: Understanding the epidemiology and clinical course of multisystem inflammatory syndrome in children (MIS-C) and its temporal association with coronavirus disease 2019 (Covid-19) is important, given the clinical and public health implications of the syndrome. METHODS: We conducted targeted surveillance for MIS-C from March 15 to May 20, 2020, in pediatric health centers across the United States. The case definition included six criteria: serious illness leading to hospitalization, an age of less than 21 years, fever that lasted for at least 24 hours, laboratory evidence of inflammation, multisystem organ involvement, and evidence of infection with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) based on reverse-transcriptase polymerase chain reaction (RT-PCR), antibody testing, or exposure to persons with Covid-19 in the past month. Clinicians abstracted the data onto standardized forms. RESULTS: We report on 186 patients with MIS-C in 26 states. The median age was 8.3 years, 115 patients (62%) were male, 135 (73%) had previously been healthy, 131 (70%) were positive for SARS-CoV-2 by RT-PCR or antibody testing, and 164 (88%) were hospitalized after April 16, 2020. Organ-system involvement included the gastrointestinal system in 171 patients (92%), cardiovascular in 149 (80%), hematologic in 142 (76%), mucocutaneous in 137 (74%), and respiratory in 131 (70%). The median duration of hospitalization was 7 days (interquartile range, 4 to 10); 148 patients (80%) received intensive care, 37 (20%) received mechanical ventilation, 90 (48%) received vasoactive support, and 4 (2%) died. Coronary-artery aneurysms (z scores ≥2.5) were documented in 15 patients (8%), and Kawasaki's disease-like features were documented in 74 (40%). Most patients (171 [92%]) had elevations in at least four biomarkers indicating inflammation. The use of immunomodulating therapies was common: intravenous immune globulin was used in 144 (77%), glucocorticoids in 91 (49%), and interleukin-6 or 1RA inhibitors in 38 (20%). CONCLUSIONS: Multisystem inflammatory syndrome in children associated with SARS-CoV-2 led to serious and life-threatening illness in previously healthy children and adolescents. (Funded by the Centers for Disease Control and Prevention.).

Multidisciplinary Guidance Regarding the Use of Immunomodulatory Therapies for Acute Coronavirus Disease 2019 in Pediatric Patients.

BACKGROUND: Immune-mediated lung injury and systemic hyperinflammation are characteristic of severe and critical coronavirus disease 2019 (COVID-19) in adults. Although the majority of severe acute respiratory syndrome coronavirus 2 infections in pediatric populations result in minimal or mild COVID-19 in the acute phase of infection, a small subset of children develop severe and even critical disease in this phase with concomitant inflammation that may benefit from immunomodulation. Therefore, guidance is needed regarding immunomodulatory therapies in the setting of acute pediatric COVID-19. This document does not provide guidance regarding the recently emergent multisystem inflammatory syndrome in children (MIS-C). METHODS: A multidisciplinary panel of pediatric subspecialty physicians and pharmacists with expertise in infectious diseases, rheumatology, hematology/oncology, and critical care medicine was convened. Guidance statements were developed based on best available evidence and expert opinion. RESULTS: The panel devised a framework for considering the use of immunomodulatory therapy based on an assessment of clinical disease severity and degree of multiorgan involvement combined with evidence of hyperinflammation. Additionally, the known rationale for consideration of each immunomodulatory approach and the associated risks and benefits was summarized. CONCLUSIONS: Immunomodulatory therapy is not recommended for the majority of pediatric patients, who typically develop mild or moderate COVID-19. For children with severe or critical illness, the use of immunomodulatory agents may be beneficial. The risks and benefits of such therapies are variable and should be evaluated on a case-by-case basis with input from appropriate specialty services. When available, the panel strongly favors immunomodulatory agent use within the context of clinical trials. The framework presented herein offers an approach to decision-making regarding immunomodulatory therapy for severe or critical pediatric COVID-19 and is informed by currently available data, while awaiting results of placebo-controlled randomized clinical trials.

Chest radiograph features of multisystem inflammatory syndrome in children (MIS-C) compared to pediatric COVID-19.

BACKGROUND: Although the radiographic features of coronavirus disease 2019 (COVID-19) in children have been described, the distinguishing features of multisystem inflammatory syndrome in children (MIS-C) associated with COVID-19 are not well characterized. OBJECTIVE: We compared the chest radiographic findings of MIS-C with those of COVID-19 and described other distinguishing imaging features of MIS-C. MATERIALS AND METHODS: We performed a retrospective case series review of children ages 0 to 18 years who were hospitalized at Children's Healthcare of Atlanta from March to May 2020 and who either met the Centers for Disease Control and Prevention (CDC) case definition for MIS-C (n=11) or who had symptomatic, laboratory-confirmed COVID-19 (n=16). Two radiologists reviewed the most severe chest radiographs for each patient. The type and distribution of pulmonary opacities and presence or absence of pleural effusions were recorded. The chest radiographs were categorized based on potential COVID-19 imaging findings as typical, indeterminate, atypical or negative. An imaging severity score was also assigned using a simplified version of the Radiographic Assessment of Lung Edema Score. Findings were statistically compared between patients with MIS-C and those with COVID-19. Additional imaging findings of MIS-C were also described. RESULTS: Radiographic features of MIS-C included pleural effusions (82% [9/11]), pulmonary consolidations (73% [8/11]) and ground glass opacities (91% [10/11]). All of the lung opacities (100% [10/10]) were bilateral, and the majority of the pleural effusions (67% [6/9]) were bilateral. Compared to children with COVID-19, children with MIS-C were significantly more likely to develop pleural effusions on chest radiograph (82% [9/11] vs. 0% [0/0], P-value <0.01) and a lower zone predominance of pulmonary opacifications (100% [10/10] vs. 38% [5/13], P-value <0.01). Children with MIS-C who also had abdominal imaging had intra-abdominal inflammatory changes. CONCLUSION: Key chest radiographic features of MIS-C versus those of COVID-19 were pleural effusions and lower zone pulmonary opacifications as well as intra-abdominal inflammation. Elucidating the distinguishing radiographic features of MIS-C may help refine the case definition and expedite diagnosis and treatment.

Burden of Illness in Households With Severe Acute Respiratory Syndrome Coronavirus 2-Infected Children.

We investigated of illness among household members of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2)-infected children receiving medical care (n = 32). We identified 144 household contacts (HCs): 58 children and 86 adults. Forty-six percent of HCs developed symptoms consistent with coronavirus disease. Child-to-adult transmission was suspected in 7 cases.

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

OBJECTIVES: 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. METHODS: 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. RESULTS: 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). CONCLUSIONS: 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.