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Background: We aimed to determine if pre-existing immunocompromising conditions (ICCs) were associated with the presentation or outcome of patients with acute coronavirus disease 2019 (COVID-19) admitted for pediatric intensive care., Methods: Fifty-five hospitals in 30 US states reported cases through the Overcoming COVID-19 public health surveillance registry. Patients <21 years admitted 12 March 2020-30 December 2021 to the pediatric intensive care unit (PICU) or high-acuity unit for acute COVID-19 were included., Results: Of 1274 patients, 105 (8.2%) had an ICC, including 33 (31.4%) hematologic malignancies, 24 (22.9%) primary immunodeficiencies and disorders of hematopoietic cells, 19 (18.1%) nonmalignant organ failure with solid-organ transplantation, 16 (15.2%) solid tumors, and 13 (12.4%) autoimmune disorders. Patients with ICCs were older, had more underlying renal conditions, and had lower white blood cell and platelet counts than those without ICCs, but had similar clinical disease severity upon admission. In-hospital mortality from COVID-19 was higher (11.4% vs 4.6%, P = .005) and hospitalization was longer (P = .01) in patients with ICCs. New major morbidities upon discharge were not different between those with and without ICC (10.5% vs 13.9%, P = .40). In patients with ICCs, bacterial coinfection was more common in those with life-threatening COVID-19., Conclusions: In this national case series of patients <21 years of age with acute COVID-19 admitted for intensive care, existence of a prior ICCs were associated with worse clinical outcomes. Reassuringly, most patients with ICCs hospitalized in the PICU for severe acute COVID-19 survived and were discharged home without new severe morbidities., Competing Interests: Potential conflicts of interest. B. M. C. reports grants from NHLBI, American Lung Association, Doris Duke Foundation/Walder Foundation, and American Thoracic Society; payment for expert testimony from Tripplett Woolf Garretson; and participation on a multidisciplinary team for Sobi. N. B. H. reports grants from Sanofi, Quidel, and Merck. C. V. H. reports royalties, consulting fees, for Reviewer for Up To Date and Dynamed clinical databases; payment for presentations from Biofire; and expert consultation for the AstraZeneca FluMist Board. A. G. R. reports licenses as a Section Editor for Pediatric Critical Care Medicine, UpToDate, Inc; consulting fees from ThermoFisher, Inotrem; honoraria from a Grand Rounds presentation at St. Jude; support for meetings and/or travel from International Sepsis Forum, Institut Merieux, ThermoFisher; participation on an advisory board for the NIH Grace Study, REMAP-CAP, NIH-PREVENT-VILI; a medical advisory board member for Families Fighting Flu; chair member for International Sepsis Forum; and received reagents from Illumina, Inc. M. K. reports support for meetings and/or travel from the National Institute of Health (NIH) and a role on an advisory board for KultureCity. H. D. reports honoraria from Delex Pharma International, Inc. N. Z. C. reports grants from Cincinnati Children's Hospital Medical Center. J. C. F. reports grants from the National Institute of Diabetes and Digestive and Kidney Diseases (K23DK119463 and P50DK114786), and Pennsylvania CURE Grant. M. W. H. reports licenses from Kiadis, sub-board service for the American Board of Pediatrics, participation on a Data and Safety Monitoring Board (DSMB) for Abbvie, and receipt of drugs from Partner Therapeutics and Sobi. J. C. reports receipt of equipment from Illumina. B. L. reports receipt of an Immune Deficiency Foundation Research Grant. G. E. M. reports payment for expert testimony from Orlando Health, Bush Ross, Hall, Schiefflin & Smith, PA, Poole Brooks and Plumlee, PA, Hilltop Specialty Insurance, Smith, Hulsey, and Busey, PA. J. E. S. reports grants from the Food and Drug Administration (FDA), consulting fees from the Association for Professionals in Infection Control and Epidemiology (APIC), payment for presentations from the American Academy of Pediatrics, and participation on an advisory board for the American Association of Medical Colleges. All other authors report no potential conflicts. All authors have submitted the ICMJE Form for Disclosure of Potential Conflicts of Interest. Conflicts that the editors consider relevant to the content of the manuscript have been disclosed., (© The Author(s) 2024. Published by Oxford University Press on behalf of Infectious Diseases Society of America. All rights reserved. For commercial re-use, please contact reprints@oup.com for reprints and translation rights for reprints. All other permissions can be obtained through our RightsLink service via the Permissions link on the article page on our site—for further information please contact journals.permissions@oup.com.)

Pediatric COVID-19 vaccination is effective in preventing COVID-19-related hospitalization, but duration of protection of the original monovalent vaccine during SARS-CoV-2 Omicron predominance merits evaluation, particularly given low coverage with updated COVID-19 vaccines. During December 19, 2021-October 29, 2023, the Overcoming COVID-19 Network evaluated vaccine effectiveness (VE) of ≥2 original monovalent COVID-19 mRNA vaccine doses against COVID-19-related hospitalization and critical illness among U.S. children and adolescents aged 5-18 years, using a case-control design. Too few children and adolescents received bivalent or updated monovalent vaccines to separately evaluate their effectiveness. Most case-patients (persons with a positive SARS-CoV-2 test result) were unvaccinated, despite the high frequency of reported underlying conditions associated with severe COVID-19. VE of the original monovalent vaccine against COVID-19-related hospitalizations was 52% (95% CI = 33%-66%) when the most recent dose was administered <120 days before hospitalization and 19% (95% CI = 2%-32%) if the interval was 120-364 days. VE of the original monovalent vaccine against COVID-19-related hospitalization was 31% (95% CI = 18%-43%) if the last dose was received any time within the previous year. VE against critical COVID-19-related illness, defined as receipt of noninvasive or invasive mechanical ventilation, vasoactive infusions, extracorporeal membrane oxygenation, and illness resulting in death, was 57% (95% CI = 21%-76%) when the most recent dose was received <120 days before hospitalization, 25% (95% CI = -9% to 49%) if it was received 120-364 days before hospitalization, and 38% (95% CI = 15%-55%) if the last dose was received any time within the previous year. VE was similar after excluding children and adolescents with documented immunocompromising conditions. Because of the low frequency of children who received updated COVID-19 vaccines and waning effectiveness of original monovalent doses, these data support CDC recommendations that all children and adolescents receive updated COVID-19 vaccines to protect against severe COVID-19., Competing Interests: All authors have completed and submitted the International Committee of Medical Journal Editors form for disclosure of potential conflicts of interest. Danielle M. Zerr reports institutional support from Merck and consulting fees from AlloVir. Melissa S. Stockwell reports institutional support from the National Institutes of Health (NIH). Mary Allen Staat reports institutional support from NIH, Pfizer, Cepheid, and Merck and receipt of royalties from UpToDate for chapters on adoption and immunization. Jennifer E. Schuster reports institutional support from NIH, the Food and Drug Administration, and the State of Missouri, receipt of an honorarium from the Missouri chapter of the American Academy of Pediatrics (AAP) and participation on the advisory board of the Association of American Medical Colleges and the Association for Professionals in Infection Control and Epidemiology. Adrienne G. Randolph reports institutional support from NIH, royalties for UpToDate for work as a section editor, consulting fees from Inotrem, Inc. and ThermoFisher, Inc., receipt of honoraria from St. Jude Children’s Research Center and Volition, Inc., travel support from the International Sepsis Forum, participation on a data safety monitoring board for NIH and the Randomized Embedded Multifactorial Adaptive Platform for Community-acquired Pneumonia, serving as chair (2023–2024) of the International Sepsis Forum, and receipt of equipment from Illumina, Inc. (for institutional use). Pia S. Pannaraj reports institutional support from the National Institute on Allergy and Infectious Diseases, the National Institute of Child Health and Human Development, and AstraZeneca, receipt of honoraria from IDweek and Infectious Diseases in Children Symposium, payment for expert testimony from BBV Law Firm and Helsell Fetterman Law Firm, waiver of registration fee for IDweek meeting, uncompensated participation on three data safety monitoring boards 1) Phase II, Double-Blind, Multicenter, Randomized, Placebo-Controlled Trial to Assess the Safety, Reactogenicity and Immunogenicity of One or Two Doses of Multimeric-001 (M-001) Followed by One or Two Doses of an Influenza A/H7N9 Vaccine, 2) Therapeutic Fecal Transplant on the Gut Microbiome in Children with Ulcerative Colitis, and 3) Safety of Fecal Transplant in maintenance of pediatric Crohn's disease), and uncompensated services as president of the California Immunization Coalition and the AAP Committee on Infectious Diseases. Kanokporn Mongkolrattanothai reports institutional support from Gilead. Samina S. Bhumbra reports travel support from CDC to present a plenary lecture at the Conference on Emerging Infectious Diseases. Kathleen Chiotos reports institutional support from the Agency for Healthcare Research and Quality and travel support from IDWeek (2022), Society for Healthcare Epidemiology of America (2022), and Pediatric Academic Societies (2022). Bria M. Coates reports institutional support from the National Heart, Lung, and Blood Institute and the American Lung Association, payment for expert testimony from Triplett Woolf Garretson, and participation on a Sobi Data Safety Monitoring Board. Thomas J. Connors reports grant support from NIH. Melissa L. Cullimore reports institutional support from NIH. Heidi R. Flori reports receipt of consulting fees from Lucira Health for advisory role for rapid diagnostic devices for COVID-19. Shira J. Gertz reports ownership of Pfizer stock. Ivan Gonzalez reports receipt of honoraria from the Florida Chapter of AAP for educational infection control initiatives and travel support from the Florida Chapter of AAP for regional conference attendance. Judith A. Guzman-Cottrill reports receipt of a consulting contract from the Oregon Health Authority. Natasha B. Halasa reports receipt of investigator-initiated grants from Sanofi, Quidel, and Merck. Charlotte V. Hobbs reports receipt of consulting fees from Dynamed.com and royalties as a content reviewer for UpToDate.com. Janet R. Hume reports institutional support from NIH and uncompensated participation on a data safety monitoring board for a study at the University of Minnesota (Magnesium sulfate as adjuvant analgesia and its effect on opiate use by postoperative transplant patients in the pediatric intensive care unit). Satoshi Kamidani reports institutional support from NIH, Pfizer, Moderna, Meissa, and Bavarian Nordic and receipt of honoraria from AAP. Michele Kong reports institutional support from NIH and uncompensated service on the Board of Directors for Jefferson County Department of Health, Callahan Eye Hospital, University of Alabama at Birmingham, and KultureCity. Regina M. Simeone reports payments received by her spouse from a previously managed Pfizer investment, which was sold in April 2023. No other potential conflicts of interest were disclosed.

Background and Objectives: In June 2022, the mRNA COVID-19 vaccination was recommended for young children. We examined clinical characteristics and factors associated with vaccination status among vaccine-eligible young children hospitalized for acute COVID-19., Methods: We enrolled inpatients 8 months to <5 years of age with acute community-acquired COVID-19 across 28 US pediatric hospitals from September 20, 2022 to May 31, 2023. We assessed demographic and clinical factors, including the highest level of respiratory support, and vaccination status defined as unvaccinated, incomplete, or complete primary series [at least 2 (Moderna) or 3 (Pfizer-BioNTech) mRNA vaccine doses ≥14 days before hospitalization]., Results: Among 597 children, 174 (29.1%) patients were admitted to the intensive care unit and 75 (12.6%) had a life-threatening illness, including 51 (8.5%) requiring invasive mechanical ventilation. Children with underlying respiratory and neurologic/neuromuscular conditions more frequently received higher respiratory support. Only 4.5% of children hospitalized for COVID-19 (n = 27) had completed their primary COVID-19 vaccination series and 7.0% (n = 42) of children initiated but did not complete their primary series. Among 528 unvaccinated children, nearly half (n = 251) were previously healthy, 3 of them required extracorporeal membrane oxygenation for acute COVID-19 and 1 died., Conclusions: Most young children hospitalized for acute COVID-19, including most children admitted to the intensive care unit and with life-threatening illness, had not initiated COVID-19 vaccination despite being eligible. Nearly half of these children had no underlying conditions. Of the small percentage of children who initiated a COVID-19 primary series, most had not completed it before hospitalization., Competing Interests: The authors have no conflicts of interest to disclose., (Copyright © 2023 Wolters Kluwer Health, Inc. All rights reserved.)

Infants aged <6 months are not eligible for COVID-19 vaccination. Vaccination during pregnancy has been associated with protection against infant COVID-19-related hospitalization. The Overcoming COVID-19 Network conducted a case-control study during March 9, 2022-May 31, 2023, to evaluate the effectiveness of maternal receipt of a COVID-19 vaccine dose (vaccine effectiveness [VE]) during pregnancy against COVID-19-related hospitalization in infants aged <6 months and a subset of infants aged <3 months. VE was calculated as (1 - adjusted odds ratio) x 100% among all infants aged <6 months and <3 months. Case-patients (infants hospitalized for COVID-19 outside of birth hospitalization and who had a positive SARS-CoV-2 test result) and control patients (infants hospitalized for COVID-19-like illness with a negative SARS-CoV-2 test result) were compared. Odds ratios were determined using multivariable logistic regression, comparing the odds of receipt of a maternal COVID-19 vaccine dose (completion of a 2-dose vaccination series or a third or higher dose) during pregnancy with maternal nonvaccination between case- and control patients. VE of maternal vaccination during pregnancy against COVID-19-related hospitalization was 35% (95% CI = 15%-51%) among infants aged <6 months and 54% (95% CI = 32%-68%) among infants aged <3 months. Intensive care unit admissions occurred in 23% of all case-patients, and invasive mechanical ventilation was more common among infants of unvaccinated (9%) compared with vaccinated mothers (1%) (p = 0.02). Maternal vaccination during pregnancy provides some protection against COVID-19-related hospitalizations among infants, particularly those aged <3 months. Expectant mothers should remain current with COVID-19 vaccination to protect themselves and their infants from hospitalization and severe outcomes associated with COVID-19., Competing Interests: All authors have completed and submitted the International Committee of Medical Journal Editors form for disclosure of potential conflicts of interest. Regina M. Simeone reports payments received by her spouse from a previously managed Pfizer investment, which was sold in April 2023. Natasha Halasa reports grant support from Sanofi, Quidel, and Merck, and testing and vaccine donation for Sanofi; and an education grant for delivering a lecture. Satoshi Kamidani reports institutional support from the National Institutes of Health (NIH), Pfizer, Meissa, and Emergent BioSolutions; and honoraria from the American Academy of Pediatrics (AAP). Pia S. Pannaraj reports institutional support from AstraZeneca and NIH, payment for expert testimony, and unpaid service on the AAP’s Committee on Infectious Diseases and the California Immunization Coalition. Aline B. Maddux reports support from the International Severe Acute Respiratory and Emerging Infections Consortium for conference attendance. Charlotte V. Hobbs reports receipt of consulting fees from Dynamed.com for review of a clinical database and honoraria from bioMérieux for speaking at Biofire (bioMérieux) 2022. Julie A. Boom reports receipt of royalties from UpToDate, Inc. for chapter authorship. Michele Kong reports institutional support from NIH and KultureCity board membership. Jennifer E. Schuster reports institutional support from NIH and the Food and Drug Administration, consulting fees from the Association for Professionals in Infection Control and Epidemiology and the Association of American Medical Colleges, and honoraria from the Missouri American Academy of Pediatrics. Janet R. Hume reports institutional support from the National Institute of Child Health and Human Development and NIH, consulting fees from Entegrion, and uncompensated service on a data safety managing board for an institutional study at the University of Minnesota. Mary A. Staat reports institutional support from NIH, Merck, and Cepheid, and royalties from UpToDate, Inc. for unrelated subject matter. Emily R. Levy reports institutional support from the National Institute on Allergy and Infectious Diseases and consulting fees from the Health Resources and Service Administration Regional Pediatric Pandemic Network. Heidi R. Flori reports consulting fees from NOTA Laboratories and Lucira Health, unrelated to the current work; housing compensation from the Society of Critical Care Medicine for participation in the Pediatric Surviving Sepsis Campaign; and unfunded participation on a data safety monitory board for normoxia in cardiothoracic surgery and cyclodextrin in Niemann-Pick disease. Adrienne G. Randolph reports grant support from NIH for work related to COVID-19, royalties from UpToDate, Inc. for work as the Pediatric Critical Care Medicine section editor; honoraria from grand rounds presentations on multisystem inflammatory syndrome in children and sepsis; meeting attendance support from the International Sepsis Forum, participation on a data safety monitoring board for the NIH Grace Study; chair of the Families Fighting Flu International Sepsis Forum medical advisory board; and receipt of reagents from Illumina, Inc. No other potential conflicts of interest were disclosed.

Importance: Respiratory syncytial virus (RSV) is the leading cause of lower respiratory tract infections (LRTIs) and infant hospitalization worldwide., Objective: To evaluate the characteristics and outcomes of RSV-related critical illness in US infants during peak 2022 RSV transmission., Design, Setting, and Participants: This cross-sectional study used a public health prospective surveillance registry in 39 pediatric hospitals across 27 US states. Participants were infants admitted for 24 or more hours between October 17 and December 16, 2022, to a unit providing intensive care due to laboratory-confirmed RSV infection., Exposure: Respiratory syncytial virus., Main Outcomes and Measures: Data were captured on demographics, clinical characteristics, signs and symptoms, laboratory values, severity measures, and clinical outcomes, including receipt of noninvasive respiratory support, invasive mechanical ventilation, vasopressors or extracorporeal membrane oxygenation, and death. Mixed-effects multivariable log-binomial regression models were used to assess associations between intubation status and demographic factors, gestational age, and underlying conditions, including hospital as a random effect to account for between-site heterogeneity., Results: The first 15 to 20 consecutive eligible infants from each site were included for a target sample size of 600. Among the 600 infants, the median (IQR) age was 2.6 (1.4-6.0) months; 361 (60.2%) were male, 169 (28.9%) were born prematurely, and 487 (81.2%) had no underlying medical conditions. Primary reasons for admission included LRTI (594 infants [99.0%]) and apnea or bradycardia (77 infants [12.8%]). Overall, 143 infants (23.8%) received invasive mechanical ventilation (median [IQR], 6.0 [4.0-10.0] days). The highest level of respiratory support for nonintubated infants was high-flow nasal cannula (243 infants [40.5%]), followed by bilevel positive airway pressure (150 infants [25.0%]) and continuous positive airway pressure (52 infants [8.7%]). Infants younger than 3 months, those born prematurely (gestational age <37 weeks), or those publicly insured were at higher risk for intubation. Four infants (0.7%) received extracorporeal membrane oxygenation, and 2 died. The median (IQR) length of hospitalization for survivors was 5 (4-10) days., Conclusions and Relevance: In this cross-sectional study, most US infants who required intensive care for RSV LRTIs were young, healthy, and born at term. These findings highlight the need for RSV preventive interventions targeting all infants to reduce the burden of severe RSV illness.

Background: In a 2020 pilot case-control study using medical records, we reported that non-Hispanic Black children were more likely to develop multisystem inflammatory syndrome in children (MIS-C) after adjustment for sociodemographic factors and underlying medical conditions. Using structured interviews, we investigated patient, household, and community factors underlying MIS-C likelihood., Methods: MIS-C case patients hospitalized in 2021 across 14 US pediatric hospitals were matched by age and site to outpatient controls testing positive for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) within 3 months of the admission date. Caregiver interviews queried race/ethnicity, medical history, and household and potential community exposures 1 month before MIS-C hospitalization (case-patients) or after SARS-CoV-2 infection (controls). We calculated adjusted odds ratios (aOR) using mixed-effects multivariable logistic regression., Results: Among 275 case patients and 496 controls, race/ethnicity, social vulnerability and patient or family history of autoimmune/rheumatologic disease were not associated with MIS-C. In previously healthy children, MIS-C was associated with a history of hospitalization for an infection [aOR: 4.8; 95% confidence interval (CI): 2.1-11.0]. Household crowding (aOR: 1.7; 95% CI: 1.2-2.6), large event attendance (aOR: 1.7; 95% CI: 1.3-2.1), school attendance with limited masking (aOR: 2.6; 95% CI: 1.1-6.6), public transit use (aOR: 1.8; 95% CI: 1.4-2.4) and co-resident testing positive for SARS-CoV-2 (aOR: 2.2; 95% CI: 1.3-3.7) were associated with increased MIS-C likelihood, with risk increasing with the number of these factors., Conclusions: From caregiver interviews, we clarify household and community exposures associated with MIS-C; however, we did not confirm prior associations between sociodemographic factors and MIS-C., (Copyright © 2023 Wolters Kluwer Health, Inc. All rights reserved.)

Objectives: Extracorporeal membrane oxygenation (ECMO) has been used successfully to support adults with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2)-related cardiac or respiratory failure refractory to conventional therapies. Comprehensive reports of children and adolescents with SARS-CoV-2-related ECMO support for conditions, including multisystem inflammatory syndrome in children (MIS-C) and acute COVID-19, are needed., Design: Case series of patients from the Overcoming COVID-19 public health surveillance registry., Setting: Sixty-three hospitals in 32 U.S. states reporting to the registry between March 15, 2020, and December 31, 2021., Patients: Patients less than 21 years admitted to the ICU meeting Centers for Disease Control criteria for MIS-C or acute COVID-19., Interventions: None., Measurements and Main Results: The final cohort included 2,733 patients with MIS-C ( n = 1,530; 37 [2.4%] requiring ECMO) or acute COVID-19 ( n = 1,203; 71 [5.9%] requiring ECMO). ECMO patients in both groups were older than those without ECMO support (MIS-C median 15.4 vs 9.9 yr; acute COVID-19 median 15.3 vs 13.6 yr). The body mass index percentile was similar in the MIS-C ECMO versus no ECMO groups (89.9 vs 85.8; p = 0.22) but higher in the COVID-19 ECMO versus no ECMO groups (98.3 vs 96.5; p = 0.03). Patients on ECMO with MIS-C versus COVID-19 were supported more often with venoarterial ECMO (92% vs 41%) for primary cardiac indications (87% vs 23%), had ECMO initiated earlier (median 1 vs 5 d from hospitalization), shorter ECMO courses (median 3.9 vs 14 d), shorter hospital length of stay (median 20 vs 52 d), lower in-hospital mortality (27% vs 37%), and less major morbidity at discharge in survivors (new tracheostomy, oxygen or mechanical ventilation need or neurologic deficit; 0% vs 11%, 0% vs 20%, and 8% vs 15%, respectively). Most patients with MIS-C requiring ECMO support (87%) were admitted during the pre-Delta (variant B.1.617.2) period, while most patients with acute COVID-19 requiring ECMO support (70%) were admitted during the Delta variant period., Conclusions: ECMO support for SARS-CoV-2-related critical illness was uncommon, but type, initiation, and duration of ECMO use in MIS-C and acute COVID-19 were markedly different. Like pre-pandemic pediatric ECMO cohorts, most patients survived to hospital discharge., Competing Interests: Dr. Bembea’s institution received funding from the National Institute of Neurological Disorders and Stroke (R01NS106292) and Grifols Investigator Sponsored Research Grant. Drs. Bembea, Heidemann, Zinter, and Randolph received support for article research from the National Institutes of Health (NIH). Dr. Thiagarjan’s institution received funding from the U.S. Department of Defense (Peer Reviewed Medical Research Project Clinical Trial Award No. W81XWH2210301 Trial of Indication-based Transfusion of Red blood cells in Extracorporeal Membrane Oxygenation); he received funding from Society of Critical Care Medicine and the Extracorporeal Life Support Organization. Drs. Young’s, McCadden’s, Newhams’s, Kucuak’s, Mack’s, Fitzgerald’s, Rowan’s, Maddux’s, Kolmar’s, Heidemann’s, Schwartz’s, Kong’s, Crandall’s, Singh’s, Schuster’s, Hall’s, Wellnitz’s, Maamari’s, Gaspers’s, Nofziger’s, Cullimore’s, Halasa’s, McLaughlin’s, Pannaraj’s, Cvijanovich’s, Coates’s, Horwitz’s, Hobbs’s, Dapul’s, and Randolph’s institutions received funding from the U.S. Centers for Disease Control and Prevention (CDC). Dr. McCadden disclosed work for hire. Dr. Newhams’ institution received funding from the National Institute of Allergy and Infectious Diseases. Drs. Fitzgerald’s, Kong’s, Cullimore’s, Cvijanovich’s, and Randolph’s institutions received funding from the NIH. Dr. Rowan’s institution received funding from the National Heart, Lung, and Blood Institute (NHLBI) (K23HL150244). Dr. Maddux’s institution received funding from the National Institute of Child Health and Human Development (K23HD096018). Drs. Irby, Crandall, Singh, Wellnitz, Nofziger, Bradford, McLaughlin, Coates, Hobbs, and Zambrano received support for article research from the CDC. Dr. Schuster’s institution received funding from Merck. Dr. Hall received funding from Abbvie, Kiadis, and the American Board of Pediatrics. Dr. Wellnitz’s institution received funding from the University of Pennsylvania (prime sponsor NIH) and the University of Nebraska (prime sponsor Administration for Strategic Preparedness and Response). Dr. Gaspers received funding from Abbott Laboratories. Dr. Munoz’s institution received funding from Boston’s Children’s Hospital; he received funding from the University of Texas Health Science Center at Houston. Dr. Halasa’s institution received funding from Sanofi. Dr. McLaughlin received funding from expert witness fees from two entities. Dr. Pannaraj’s institution received funding from AstraZeneca and Pfizer. Dr. Coates’ institution received funding from the NHLBI and the American Lung Association; she received funding from Sobi. Drs. Hobbs and Randolph received funding from UpToDate. Dr. Hobbs received funding from Dynamed.com; she disclosed that she was a speaker for Biomerieux 2021–2022. Drs. Zambrano and Campbell disclosed government work. Dr. Randolph had full access to all the data in the investigation and takes responsibility for the integrity of the data and the accuracy of the data analysis. The remaining authors have disclosed that they do not have any potential conflicts of interest., (Copyright © 2023 by the Society of Critical Care Medicine and the World Federation of Pediatric Intensive and Critical Care Societies.)

Background: Pfizer-BioNTech COVID-19 vaccine received emergency use authorization for persons ≥ 16 years in December 2020 and for adolescents 12-15 years in May 2021. Despite the clear benefits and favorable safety profile, vaccine uptake in adolescents has been suboptimal. We sought to assess factors associated with COVID-19 non-vaccination in adolescents 12-18 years of age., Methods: Between June 1, 2021 and April 29, 2022, we assessed factors associated with COVID-19 non-vaccination in hospitalized adolescents ages 12-18 years enrolled in the Overcoming COVID-19 vaccine effectiveness network. Demographic characteristics and clinical information were captured through parent interviews and/or electronic medical record abstraction; COVID-19 vaccination was assessed through documented sources. We assessed associations between receipt of the COVID-19 vaccine and demographic and clinical factors using univariate and multivariable logistic regression and estimated adjusted odds ratios (aOR) for each factor associated with non-vaccination., Results: Among 1665 hospitalized adolescents without COVID-19, 56% were unvaccinated. Unvaccinated adolescents were younger (median age 15.1 years vs. 15.4 years, p < .01) and resided in areas with higher social vulnerability index (SVI) scores (median 0.6 vs 0.5, p < .001) than vaccinated adolescents. Residence in the Midwest [aOR 2.60 (95% CI: 1.80, 3.79)] or South [aOR 2.49 (95% CI: 1.77, 3.54)] US census regions, rarely or never receiving influenza vaccine [aOR 5.31 (95% CI: 3.81, 7.47)], and rarely or never taking precautions against COVID-19 [aOR 3.17 (95% CI: 1.94, 5.31)] were associated with non-vaccination against COVID-19., Conclusions: Efforts to increase COVID-19 vaccination of adolescents should focus on persons with geographic, socioeconomic, and medical risk factors associated with non-vaccination., (© The Author(s) 2022. Published by Oxford University Press on behalf of The Journal of the Pediatric Infectious Diseases Society. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.)

Background: Multisystem inflammatory syndrome in children (MIS-C), linked to antecedent severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection, is associated with considerable morbidity. Prevention of SARS-CoV-2 infection or coronavirus disease 2019 (COVID-19) by vaccination might also decrease MIS-C likelihood., Methods: In a multicenter, case-control, public health investigation of children ages 5-18 years hospitalized from 1 July 2021 to 7 April 2022, we compared the odds of being fully vaccinated (2 doses of BNT162b2 vaccine ≥28 days before hospital admission) between MIS-C case-patients and hospital-based controls who tested negative for SARS-CoV-2. These associations were examined by age group, timing of vaccination, and periods of Delta and Omicron variant predominance using multivariable logistic regression., Results: We compared 304 MIS-C case-patients (280 [92%] unvaccinated) with 502 controls (346 [69%] unvaccinated). MIS-C was associated with decreased likelihood of vaccination (adjusted OR [aOR]: .16; 95% CI: .10-.26), including among children ages 5-11 years (aOR: .22; 95% CI: .10-.52), ages 12-18 years (aOR: .10; 95% CI: .05-.19), and during the Delta (aOR: .06; 95% CI: .02-.15) and Omicron (aOR: .22; 95% CI: .11-.42) variant-predominant periods. This association persisted beyond 120 days after the second dose (aOR: .08; 95% CI: .03-.22) in 12-18-year-olds. Among all MIS-C case-patients, 187 (62%) required intensive care unit admission and 280 (92%) vaccine-eligible case-patients were unvaccinated., Conclusions: Vaccination with 2 doses of BNT162b2 is associated with reduced likelihood of MIS-C in children ages 5-18 years. Most vaccine-eligible hospitalized patients with MIS-C were unvaccinated., Competing Interests: Potential conflicts of interest. J. E. S. reports institutional support from Merck for an RSV research study, unrelated to the current work. A. G. R. reports institutional support from the National Institute of Allergy and Infectious Diseases (NIAID), National Institutes of Health (NIH); royalties from UpToDate as the Pediatric Critical Care Section Editor; and participation on a data safety monitoring board (DSMB) for a National Institute of Child Health and Human Development (NICHD)–funded study. P. S. P. reports institutional support from AstraZeneca and Pfizer, consulting fees from Sanofi-Pasteur and Seqirus, payment from law firms for expert testimony, participation on a Division of Microbiology and Infectious Diseases DSMB (paid to author), and an unpaid leadership role in the California Immunization Coalition. R. A. N. reports institutional support from NIH for participation in a multicenter influenza study. S. K. reports institutional support from NIH and Pfizer. C. V. H. reports consulting fees from Dynamed (clinical database, reviewer) and honoraria from Biofire/Biomerieux, and funding from CDC to the University of Mississippi Medical Center. N. B. H. reports grants from Sanofi and Quidel and an educational grant from Genentech. N. Z. C. reports a speaker’s registration discount at the Society of Critical Care Medicine meeting and grants or contracts from the NIH, unrelated to this work and paid to their institution. S. S. B. reports receipt of an NIH, NIAID training grant during 1 September 2019–31 August 2020 (T32AI007637). M. L. C. reports grants or contracts unrelated to this work from the CDC, paid to their institution. H. R. F. reports grants or contracts unrelated to this work from the National Heart, Lung, and Blood Institute (NHLBI) and NICHD, paid to their institution; support for attending meetings and/or travel from the Society of Critical Care Medicine; participation on a DSMB for a cardiothoracic surgery trial—single center—and for intrathecal chemotherapy trial; an unpaid leadership or fiduciary role on the Michigan Thoracic Society Executive Committee and PALISI Network Executive Committee; other financial or nonfinancial interests in the Lucira Health advisory committee and Aerogen Pharma—advisor—unfunded. J. R. H. reports grants or contracts unrelated to this work from the NICHD, paid to their institution; participation on a DSMB for institutional study at the University of Minnesota, “Magnesium sulfate as adjuvant analgesia and its effect on opiate use by post-operative transplant patients in the pediatric ICU” (Magnesium sulfate as Investigational New Drug [IND] per the Food and Drug Administration [FDA]; no financial reimbursements). E. R. L. reports the following grants or contracts unrelated to this work and paid to their institution—AI 144301-01: An Observational Cohort Study to Determine Late Outcomes and Immunological Responses after Infection with SARS-CoV-2 in Children with and without MIS-C; and NIH AI 154470-01: Immunobiology of Influenza Virus-related Critical Illness in Young Hosts. E. H. M. reports an unpaid role as Vice President of the South Carolina Chapter of the American Academy of Pediatrics. L. S. reports conference attendance allowance from Medical University of South Carolina. Matthew Zinter reports the following grant or contract unrelated to this work: NHLBI K23HL146936. All other authors report no potential conflicts. All authors have submitted the ICMJE Form for Disclosure of Potential Conflicts of Interest. Conflicts that the editors consider relevant to the content of the manuscript have been disclosed., (Published by Oxford University Press on behalf of Infectious Diseases Society of America 2022.)

Importance: Data are limited regarding adverse reactions after COVID-19 vaccination in patients with a history of multisystem inflammatory syndrome in children (MIS-C). The lack of vaccine safety data in this unique population may cause hesitancy and concern for many families and health care professionals., Objective: To describe adverse reactions following COVID-19 vaccination in patients with a history of MIS-C., Design, Setting, and Participants: In this multicenter cross-sectional study including 22 North American centers participating in a National Heart, Lung, and Blood Institute, National Institutes of Health-sponsored study, Long-Term Outcomes After the Multisystem Inflammatory Syndrome in Children (MUSIC), patients with a prior diagnosis of MIS-C who were eligible for COVID-19 vaccination (age ≥5 years; ≥90 days after MIS-C diagnosis) were surveyed between December 13, 2021, and February 18, 2022, regarding COVID-19 vaccination status and adverse reactions., Exposures: COVID-19 vaccination after MIS-C diagnosis., Main Outcomes and Measures: The main outcome was adverse reactions following COVID-19 vaccination. Comparisons were made using the Wilcoxon rank sum test for continuous variables and the χ2 or Fisher exact test for categorical variables., Results: Of 385 vaccine-eligible patients who were surveyed, 185 (48.1%) received at least 1 vaccine dose; 136 of the vaccinated patients (73.5%) were male, and the median age was 12.2 years (IQR, 9.5-14.7 years). Among vaccinated patients, 1 (0.5%) identified as American Indian/Alaska Native, non-Hispanic; 9 (4.9%) as Asian, non-Hispanic; 45 (24.3%) as Black, non-Hispanic; 59 (31.9%) as Hispanic or Latino; 53 (28.6%) as White, non-Hispanic; 2 (1.1%) as multiracial, non-Hispanic; and 2 (1.1%) as other, non-Hispanic; 14 (7.6%) had unknown or undeclared race and ethnicity. The median time from MIS-C diagnosis to first vaccine dose was 9.0 months (IQR, 5.1-11.9 months); 31 patients (16.8%) received 1 dose, 142 (76.8%) received 2 doses, and 12 (6.5%) received 3 doses. Almost all patients received the BNT162b2 vaccine (347 of 351 vaccine doses [98.9%]). Minor adverse reactions were observed in 90 patients (48.6%) and were most often arm soreness (62 patients [33.5%]) and/or fatigue (32 [17.3%]). In 32 patients (17.3%), adverse reactions were treated with medications, most commonly acetaminophen (21 patients [11.4%]) or ibuprofen (11 [5.9%]). Four patients (2.2%) sought medical evaluation, but none required testing or hospitalization. There were no patients with any serious adverse events, including myocarditis or recurrence of MIS-C., Conclusions and Relevance: In this cross-sectional study of patients with a history of MIS-C, no serious adverse events were reported after COVID-19 vaccination. These findings suggest that the safety profile of COVID-19 vaccination administered at least 90 days following MIS-C diagnosis appears to be similar to that in the general population.

Importance: In 2020 during the COVID-19 pandemic, neurologic involvement was common in children and adolescents hospitalized in the United States for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2)-related complications., Objective: To provide an update on the spectrum of SARS-CoV-2-related neurologic involvement among children and adolescents in 2021., Design, Setting, and Participants: Case series investigation of patients reported to public health surveillance hospitalized with SARS-CoV-2-related illness between December 15, 2020, and December 31, 2021, in 55 US hospitals in 31 states with follow-up at hospital discharge. A total of 2253 patients were enrolled during the investigation period. Patients suspected of having multisystem inflammatory syndrome in children (MIS-C) who did not meet criteria (n = 85) were excluded. Patients (<21 years) with positive SARS-CoV-2 test results (reverse transcriptase-polymerase chain reaction and/or antibody) meeting criteria for MIS-C or acute COVID-19 were included in the analysis., Exposure: SARS-CoV-2 infection., Main Outcomes and Measures: Patients with neurologic involvement had acute neurologic signs, symptoms, or diseases on presentation or during hospitalization. Life-threatening neurologic involvement was adjudicated by experts based on clinical and/or neuroradiological features. Type and severity of neurologic involvement, laboratory and imaging data, vaccination status, and hospital discharge outcomes (death or survival with new neurologic deficits)., Results: Of 2168 patients included (58% male; median age, 10.3 years), 1435 (66%) met criteria for MIS-C, and 476 (22%) had documented neurologic involvement. Patients with neurologic involvement vs without were older (median age, 12 vs 10 years) and more frequently had underlying neurologic disorders (107 of 476 [22%] vs 240 of 1692 [14%]). Among those with neurologic involvement, 42 (9%) developed acute SARS-CoV-2-related life-threatening conditions, including central nervous system infection/demyelination (n = 23; 15 with possible/confirmed encephalitis, 6 meningitis, 1 transverse myelitis, 1 nonhemorrhagic leukoencephalopathy), stroke (n = 11), severe encephalopathy (n = 5), acute fulminant cerebral edema (n = 2), and Guillain-Barré syndrome (n = 1). Ten of 42 (24%) survived with new neurologic deficits at discharge and 8 (19%) died. Among patients with life-threatening neurologic conditions, 15 of 16 vaccine-eligible patients (94%) were unvaccinated., Conclusions and Relevance: SARS-CoV-2-related neurologic involvement persisted in US children and adolescents hospitalized for COVID-19 or MIS-C in 2021 and was again mostly transient. Central nervous system infection/demyelination accounted for a higher proportion of life-threatening conditions, and most vaccine-eligible patients were unvaccinated. COVID-19 vaccination may prevent some SARS-CoV-2-related neurologic complications and merits further study.

Background Cardiac complications related to COVID-19 in children and adolescents include ventricular dysfunction, myocarditis, coronary artery aneurysm, and bradyarrhythmias, but tachyarrhythmias are less understood. The goal of this study was to evaluate the frequency, characteristics, and outcomes of children and adolescents experiencing tachyarrhythmias while hospitalized for acute severe COVID-19 or multisystem inflammatory syndrome in children. Methods and Results This study involved a case series of 63 patients with tachyarrhythmias reported in a public health surveillance registry of patients aged <21 years hospitalized from March 15, 2020, to December 31, 2021, at 63 US hospitals. Patients with tachyarrhythmias were compared with patients with severe COVID-19-related complications without tachyarrhythmias. Tachyarrhythmias were reported in 22 of 1257 patients (1.8%) with acute COVID-19 and 41 of 2343 (1.7%) patients with multisystem inflammatory syndrome in children. They included supraventricular tachycardia in 28 (44%), accelerated junctional rhythm in 9 (14%), and ventricular tachycardia in 38 (60%); >1 type was reported in 12 (19%). Registry patients with versus without tachyarrhythmia were older (median age, 15.4 [range, 10.4-17.4] versus 10.0 [range, 5.4-14.8] years) and had higher illness severity on hospital admission. Intervention for treatment of tachyarrhythmia was required in 37 (59%) patients and included antiarrhythmic medication (n=31, 49%), electrical cardioversion (n=11, 17%), cardiopulmonary resuscitation (n=8, 13%), and extracorporeal membrane oxygenation (n=9, 14%). Patients with tachyarrhythmias had longer hospital length of stay than those who did not, and 9 (14%) versus 77 (2%) died. Conclusions Tachyarrhythmias were a rare complication of acute severe COVID-19 and multisystem inflammatory syndrome in children and adolescents and were associated with worse clinical outcomes, highlighting the importance of close monitoring, aggressive treatment, and postdischarge care.

Background: Infants younger than 6 months of age are at high risk for complications of coronavirus disease 2019 (Covid-19) and are not eligible for vaccination. Transplacental transfer of antibodies against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) after maternal Covid-19 vaccination may confer protection against Covid-19 in infants., Methods: We used a case-control test-negative design to assess the effectiveness of maternal vaccination during pregnancy against hospitalization for Covid-19 among infants younger than 6 months of age. Between July 1, 2021, and March 8, 2022, we enrolled infants hospitalized for Covid-19 (case infants) and infants hospitalized without Covid-19 (control infants) at 30 hospitals in 22 states. We estimated vaccine effectiveness by comparing the odds of full maternal vaccination (two doses of mRNA vaccine) among case infants and control infants during circulation of the B.1.617.2 (delta) variant (July 1, 2021, to December 18, 2021) and the B.1.1.259 (omicron) variant (December 19, 2021, to March 8, 2022)., Results: A total of 537 case infants (181 of whom had been admitted to a hospital during the delta period and 356 during the omicron period; median age, 2 months) and 512 control infants were enrolled and included in the analyses; 16% of the case infants and 29% of the control infants had been born to mothers who had been fully vaccinated against Covid-19 during pregnancy. Among the case infants, 113 (21%) received intensive care (64 [12%] received mechanical ventilation or vasoactive infusions). Two case infants died from Covid-19; neither infant's mother had been vaccinated during pregnancy. The effectiveness of maternal vaccination against hospitalization for Covid-19 among infants was 52% (95% confidence interval [CI], 33 to 65) overall, 80% (95% CI, 60 to 90) during the delta period, and 38% (95% CI, 8 to 58) during the omicron period. Effectiveness was 69% (95% CI, 50 to 80) when maternal vaccination occurred after 20 weeks of pregnancy and 38% (95% CI, 3 to 60) during the first 20 weeks of pregnancy., Conclusions: Maternal vaccination with two doses of mRNA vaccine was associated with a reduced risk of hospitalization for Covid-19, including for critical illness, among infants younger than 6 months of age. (Funded by the Centers for Disease Control and Prevention.)., (Copyright © 2022 Massachusetts Medical Society.)

Background: Spread of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) B.1.1.529 (omicron) variant, which led to increased U.S. hospitalizations for coronavirus disease 2019 (Covid-19), generated concern about immune evasion and the duration of protection from vaccines in children and adolescents., Methods: Using a case-control, test-negative design, we assessed vaccine effectiveness against laboratory-confirmed Covid-19 leading to hospitalization and against critical Covid-19 (i.e., leading to receipt of life support or to death). From July 1, 2021, to February 17, 2022, we enrolled case patients with Covid-19 and controls without Covid-19 at 31 hospitals in 23 states. We estimated vaccine effectiveness by comparing the odds of antecedent full vaccination (two doses of BNT162b2 messenger RNA vaccine) at least 14 days before illness among case patients and controls, according to time since vaccination for patients 12 to 18 years of age and in periods coinciding with circulation of B.1.617.2 (delta) (July 1, 2021, to December 18, 2021) and omicron (December 19, 2021, to February 17, 2022) among patients 5 to 11 and 12 to 18 years of age., Results: We enrolled 1185 case patients (1043 [88%] of whom were unvaccinated, 291 [25%] of whom received life support, and 14 of whom died) and 1627 controls. During the delta-predominant period, vaccine effectiveness against hospitalization for Covid-19 among adolescents 12 to 18 years of age was 93% (95% confidence interval [CI], 89 to 95) 2 to 22 weeks after vaccination and was 92% (95% CI, 80 to 97) at 23 to 44 weeks. Among adolescents 12 to 18 years of age (median interval since vaccination, 162 days) during the omicron-predominant period, vaccine effectiveness was 40% (95% CI, 9 to 60) against hospitalization for Covid-19, 79% (95% CI, 51 to 91) against critical Covid-19, and 20% (95% CI, -25 to 49) against noncritical Covid-19. During the omicron period, vaccine effectiveness against hospitalization among children 5 to 11 years of age was 68% (95% CI, 42 to 82; median interval since vaccination, 34 days)., Conclusions: BNT162b2 vaccination reduced the risk of omicron-associated hospitalization by two thirds among children 5 to 11 years of age. Although two doses provided lower protection against omicron-associated hospitalization than against delta-associated hospitalization among adolescents 12 to 18 years of age, vaccination prevented critical illness caused by either variant. (Funded by the Centers for Disease Control and Prevention.)., (Copyright © 2022 Massachusetts Medical Society.)

Background: Previous studies of severe acute respiratory syndrome coronavirus 2 infection in infants have incompletely characterized factors associated with severe illness or focused on infants born to mothers with coronavirus disease 2019 (COVID-19). Here we highlight demographics, clinical characteristics and laboratory values that differ between infants with and without severe acute COVID-19., Methods: Active surveillance was performed by the Overcoming COVID-19 network to identify children and adolescents with severe acute respiratory syndrome coronavirus 2-related illness hospitalized at 62 sites in 31 states from March 15 to December 27, 2020. We analyzed patients >7 days to <1 year old hospitalized with symptomatic acute COVID-19., Results: We report 232 infants >7 days to <1 year of age hospitalized with acute symptomatic COVID-19 from 37 US hospitals in our cohort from March 15 to December 27, 2020. Among 630 cases of severe COVID-19 in patients >7 days to <18 years old, 128 (20.3%) were infants. In infants with severe illness from the entire study period, the median age was 2 months, 66% were from racial and ethnic minority groups, 66% were previously healthy, 73% had respiratory complications, 13% received mechanical ventilation and <1% died., Conclusions: Infants accounted for over a fifth of children <18 years of age hospitalized for severe acute COVID-19, commonly manifesting with respiratory symptoms and complications. Although most infants hospitalized with COVID-19 did not suffer significant complications, longer term outcomes remain unclear. Notably, 75% of infants with severe disease were <6 months of age in this cohort study period, which predated maternal COVID-19 vaccination, underscoring the importance of maternal vaccination for COVID-19 in protecting the mother and infant., (Copyright © 2021 Wolters Kluwer Health, Inc. All rights reserved.)

Background: The increasing incidence of pediatric hospitalizations associated with coronavirus disease 2019 (Covid-19) caused by the B.1.617.2 (delta) variant of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in the United States has offered an opportunity to assess the real-world effectiveness of the BNT162b2 messenger RNA vaccine in adolescents between 12 and 18 years of age., Methods: We used a case-control, test-negative design to assess vaccine effectiveness against Covid-19 resulting in hospitalization, admission to an intensive care unit (ICU), the use of life-supporting interventions (mechanical ventilation, vasopressors, and extracorporeal membrane oxygenation), or death. Between July 1 and October 25, 2021, we screened admission logs for eligible case patients with laboratory-confirmed Covid-19 at 31 hospitals in 23 states. We estimated vaccine effectiveness by comparing the odds of antecedent full vaccination (two doses of BNT162b2) in case patients as compared with two hospital-based control groups: patients who had Covid-19-like symptoms but negative results on testing for SARS-CoV-2 (test-negative) and patients who did not have Covid-19-like symptoms (syndrome-negative)., Results: A total of 445 case patients and 777 controls were enrolled. Overall, 17 case patients (4%) and 282 controls (36%) had been fully vaccinated. Of the case patients, 180 (40%) were admitted to the ICU, and 127 (29%) required life support; only 2 patients in the ICU had been fully vaccinated. The overall effectiveness of the BNT162b2 vaccine against hospitalization for Covid-19 was 94% (95% confidence interval [CI], 90 to 96); the effectiveness was 95% (95% CI, 91 to 97) among test-negative controls and 94% (95% CI, 89 to 96) among syndrome-negative controls. The effectiveness was 98% against ICU admission and 98% against Covid-19 resulting in the receipt of life support. All 7 deaths occurred in patients who were unvaccinated., Conclusions: Among hospitalized adolescent patients, two doses of the BNT162b2 vaccine were highly effective against Covid-19-related hospitalization and ICU admission or the receipt of life support. (Funded by the Centers for Disease Control and Prevention.)., (Copyright © 2022 Massachusetts Medical Society.)

COVID-19 vaccination is recommended for persons who are pregnant, breastfeeding, trying to get pregnant now, or who might become pregnant in the future, to protect them from COVID-19. § Infants are at risk for life-threatening complications from COVID-19, including acute respiratory failure (1). Evidence from other vaccine-preventable diseases suggests that maternal immunization can provide protection to infants, especially during the high-risk first 6 months of life, through passive transplacental antibody transfer (2). Recent studies of COVID-19 vaccination during pregnancy suggest the possibility of transplacental transfer of SARS-CoV-2-specific antibodies that might provide protection to infants (3-5); however, no epidemiologic evidence currently exists for the protective benefits of maternal immunization during pregnancy against COVID-19 in infants. The Overcoming COVID-19 network conducted a test-negative, case-control study at 20 pediatric hospitals in 17 states during July 1, 2021-January 17, 2022, to assess effectiveness of maternal completion of a 2-dose primary mRNA COVID-19 vaccination series during pregnancy against COVID-19 hospitalization in infants. Among 379 hospitalized infants aged <6 months (176 with COVID-19 [case-infants] and 203 without COVID-19 [control-infants]), the median age was 2 months, 21% had at least one underlying medical condition, and 22% of case- and control-infants were born premature (<37 weeks gestation). Effectiveness of maternal vaccination during pregnancy against COVID-19 hospitalization in infants aged <6 months was 61% (95% CI = 31%-78%). Completion of a 2-dose mRNA COVID-19 vaccination series during pregnancy might help prevent COVID-19 hospitalization among infants aged <6 months., Competing Interests: All authors have completed and submitted the International Committee of Medical Journal Editors form for disclosure of potential conflicts of interest. Adrienne G. Randolph reports institutional support from the National Institute of Allergy and Infectious Diseases and National Institutes of Health (NIH) and being the UpToDate Pediatric Critical Care Section Editor. Matt S. Zinter reports institutional support from the National Heart, Lung, and Blood Institute (NHLBI), NIH and the American Thoracic Society. Laura Smallcomb reports support from the Medical University of South Carolina for conference attendance. Jennifer E. Schuster reports institutional support from Merck. Ryan A. Nofziger reports institutional support from NIH. Emily R. Levy reports institutional support from NIH. Michele Kong reports institutional support from NIH. Satoshi Kamidani reports institutional support from NIH and Pfizer. Janet R. Hume reports institutional support from the National Institute for Child Health and Development, NIH, and serving on a data safety monitoring board for an institutional study of magnesium for analgesia in complex medical patients. Charlotte V. Hobbs reports consultant fees from BioFire (bioMérieux). Natalie Z. Cvijanovich reports institutional support from NIH. Bria M. Coates reports institutional support from NHLBI, NIH, the American Lung Association, and the American Thoracic Society. Kathleen Chiotos reports institutional support from the Agency for Healthcare Research and Quality and serving as the Society for Healthcare Epidemiology of America Research Network Chair. Samina S. Bhumbra reports receipt of an NIH, National Institute for Allergy and Infectious Diseases training grant. Pia S. Pannaraj reports institutional support from AstraZeneca and Pfizer, consulting fees from Sanofi-Pasteur and Seqirus, payment from law firms for expert testimony, serving in the Division of Microbiology and Infectious Diseases, and unpaid service on the California Immunization Coalition. Mary A. Staat reports institutional support from NIH and receipt of lecture fees from the American Academy of Pediatrics for PREP ID Course. Natasha B. Halasa reports grant support from Sanofi and Quidel and honoraria from Genentech. No other potential conflicts of interest were disclosed.

To describe the impact of infectious adverse events (IAEs) during ventricular assist device (VAD) support on graft loss, infection, and rejection after pediatric heart transplant (HT). Pedimacs data were linked to Pediatric Heart Transplant Society (PHTS) data for patients receiving a VAD followed by HT between September 2012 and December 2016. Linked patients were categorized into IAE on VAD (group A) and no IAE on VAD (group B). Infectious adverse event locations included nondevice, device (external or internal), and sepsis. Post-HT outcomes for analysis were graft loss, infection, and rejection. Time-dependent analysis included Kaplan-Meier and multiphase parametric hazard function analysis. We linked 207 patients (age 9.4 ± 6.3 years). Post-HT follow-up was 19.4 patient-months (<8 days-4.1 years). Group A included 42 patients (20%) with 62 IAEs. Group B included 165 patients without an IAE. Group A patients were younger (7.4 ± 6.1 vs. 9.5 ± 6.3 years; p = 0.03), waited longer for HT (5.3 ± 4.1 vs. 2.9 ± 2.5 months; p = 0.0005), and were hospitalized longer post-HT (42 ± 59 vs. 23 ± 22 days; p = 0.05). VAD-related IAEs were rare (N = 11). Groups A and B had similar freedom from first post-HT infection, rejection, and graft loss (all p > 0.1). However, patients with VAD-related IAE were somewhat more likely to experience rejection (p = 0.03) and graft loss (p = 0.01). Children with an IAE on VAD who survive to HT are younger, wait longer for HT, and remain hospitalized longer than those without an IAE on VAD. Overall, IAE on VAD did not impact post-HT outcomes, but VAD-related IAE may be associated with graft loss and rejection., Competing Interests: Disclosure: The authors have no conflicts of interest to report., (Copyright © ASAIO 2021.)

Multisystem inflammatory syndrome in children (MIS-C) is a severe postinfectious hyperinflammatory condition, which generally occurs 2-6 weeks after a typically mild or asymptomatic infection with SARS-CoV-2, the virus that causes COVID-19 (1-3). In the United States, the BNT162b2 (Pfizer-BioNTech) COVID-19 vaccine is currently authorized for use in children and adolescents aged 5-15 years under an Emergency Use Authorization and is fully licensed by the Food and Drug Administration for persons aged ≥16 years (4). Prelicensure randomized trials in persons aged ≥5 years documented high vaccine efficacy and immunogenicity (5), § and real-world studies in persons aged 12-18 years demonstrated high vaccine effectiveness (VE) against severe COVID-19 (6). Recent evidence suggests that COVID-19 vaccination is associated with lower MIS-C incidence among adolescents (7); however, VE of the 2-dose Pfizer-BioNTech regimen against MIS-C has not been evaluated. The effectiveness of 2 doses of Pfizer-BioNTech vaccine received ≥28 days before hospital admission in preventing MIS-C was assessed using a test-negative case-control design ¶ among hospitalized patients aged 12-18 years at 24 pediatric hospitals in 20 states** during July 1-December 9, 2021, the period when most MIS-C patients could be temporally linked to SARS-CoV-2 B.1.617.2 (Delta) variant predominance. Patients with MIS-C (case-patients) and two groups of hospitalized controls matched to case-patients were evaluated: test-negative controls had at least one COVID-19-like symptom and negative SARS-CoV-2 reverse transcription-polymerase chain reaction (RT-PCR) or antigen-based assay results, and syndrome-negative controls were hospitalized patients without COVID-19-like illness. Among 102 MIS-C case-patients and 181 hospitalized controls, estimated effectiveness of 2 doses of Pfizer-BioNTech vaccine against MIS-C was 91% (95% CI = 78%-97%). All 38 MIS-C patients requiring life support were unvaccinated. Receipt of 2 doses of the Pfizer-BioNTech vaccine is associated with a high level of protection against MIS-C in persons aged 12-18 years, highlighting the importance of vaccination among all eligible children., Competing Interests: All authors have completed and submitted the International Committee of Medical Journal Editors form for disclosure of potential conflicts of interest. Jennifer E. Schuster reports institutional support from Merck for an RSV research study, unrelated to the current work. Adrienne G. Randolph reports institutional support from the National Institute of Allergy and Infectious Diseases, National Institutes of Health (NIH), royalties from UpToDate as the Pediatric Critical Care Section Editor, and participation on a data safety monitoring board (DSMB) for a National Institute of Child Health and Human Development-funded study. Pia S. Pannaraj reports institutional support from AstraZeneca and Pfizer, consulting fees from Sanofi-Pasteur and Seqirus, payment from law firms for expert testimony, participation on a Division of Microbiology and Infectious Diseases DSMB, and an unpaid leadership role in the California Immunization Coalition. Ryan A. Nofziger reports institutional support from NIH for participation in a multicenter influenza study. Satoshi Kamidani reports institutional support from NIH and Pfizer. Charlotte V. Hobbs reports consulting fees from Dynamed and honoraria from Biofire/Biomerieux. Natasha B. Halasa reports grants from Sanofi and Quidel and an educational grant from Genentech. Natalie Z. Cvijanovich reports a speaker’s registration discount at the Society of Critical Care Medicine meeting. Samina S. Bhumbra reports receipt of an NIH, NIAID training grant during September 1, 2019–August 31, 2020. No other potential conflicts of interest were disclosed.

Pfizer-BioNTech COVID-19 vaccine is authorized for use in children and adolescents aged 12-15 years and is licensed by the Food and Drug Administration (FDA) for persons aged ≥16 (1). A randomized placebo-controlled trial demonstrated an efficacy of 100% (95% confidence interval [CI] = 75.3%-100%) in preventing outpatient COVID-19 in persons aged 12-15 years (2); however, data among adolescents on vaccine effectiveness (VE) against COVID-19 in real-world settings are limited, especially among hospitalized patients. In early September 2021, U.S. pediatric COVID-19 hospitalizations reached the highest level during the pandemic (3,4). In a test-negative, case-control study at 19 pediatric hospitals in 16 states during June 1-September 30, 2021, the effectiveness of 2 doses of Pfizer-BioNTech vaccine against COVID-19 hospitalization was assessed among children and adolescents aged 12-18 years. Among 464 hospitalized persons aged 12-18 years (179 case-patients and 285 controls), the median age was 15 years, 72% had at least one underlying condition, including obesity, and 68% attended in-person school. Effectiveness of 2 doses of Pfizer-BioNTech vaccine against COVID-19 hospitalization was 93% (95% CI = 83%-97%), during the period when B.1.617.2 (Delta) was the predominant variant. This evaluation demonstrated that 2 doses of Pfizer-BioNTech vaccine are highly effective at preventing COVID-19 hospitalization among persons aged 12-18 years and reinforces the importance of vaccination to protect U.S. youths against severe COVID-19., Competing Interests: All authors have completed and submitted the International Committee of Medical Journal Editors form for disclosure of potential conflicts of interest. Natasha B. Halasa reports grants from Sanofi and Quidel outside of the submitted work. Jennifer E. Schuster reports grants from Merck outside of the submitted work. Pia S. Pannaraj reports grants from AstraZeneca and Pfizer outside of the submitted work, and personal fees from Seqirus and Nestle outside of the submitted work. No other potential conflicts of interest were disclosed.

Background: Multisystem inflammatory syndrome in children (MIS-C) consensus criteria were designed for maximal sensitivity and therefore capture patients with acute COVID-19 pneumonia., Methods: We performed unsupervised clustering on data from 1,526 patients (684 labeled MIS-C by clinicians) <21 years old hospitalized with COVID-19-related illness admitted between 15 March 2020 and 31 December 2020. We compared prevalence of assigned MIS-C labels and clinical features among clusters, followed by recursive feature elimination to identify characteristics of potentially misclassified MIS-C-labeled patients., Findings: Of 94 clinical features tested, 46 were retained for clustering. Cluster 1 patients ( N  = 498; 92% labeled MIS-C) were mostly previously healthy (71%), with mean age 7·2 ± 0·4 years, predominant cardiovascular (77%) and/or mucocutaneous (82%) involvement, high inflammatory biomarkers, and mostly SARS-CoV-2 PCR negative (60%). Cluster 2 patients ( N  = 445; 27% labeled MIS-C) frequently had pre-existing conditions (79%, with 39% respiratory), were similarly 7·4 ± 2·1 years old, and commonly had chest radiograph infiltrates (79%) and positive PCR testing (90%). Cluster 3 patients ( N  = 583; 19% labeled MIS-C) were younger (2·8 ± 2·0 y), PCR positive (86%), with less inflammation. Radiographic findings of pulmonary infiltrates and positive SARS-CoV-2 PCR accurately distinguished cluster 2 MIS-C labeled patients from cluster 1 patients., Interpretation: Using a data driven, unsupervised approach, we identified features that cluster patients into a group with high likelihood of having MIS-C. Other features identified a cluster of patients more likely to have acute severe COVID-19 pulmonary disease, and patients in this cluster labeled by clinicians as MIS-C may be misclassified. These data driven phenotypes may help refine the diagnosis of MIS-C., Competing Interests: All authors report receiving funding from the Centers for Disease Control and Prevention for the current study. AG reports receiving grants from the NIH outside of the submitted work. ABM reports receiving grants from the Francis Family Foundation and from the NIH/NICHD (K23HD096018) outside of the submitted work. CVH reports receiving consulting fees from DYNAMED and BIOFIRE outside of the submitted work. JES reports receiving grants from Merck outside of the submitted work. NBH reports receiving grants from Sanofi, Quidel, the NIH, and the CDC; consulting fees from Moderna; and an educational grant from Genetech outside of the submitted work. CMR reports receiving grants from the NIH/NHLBI (K23HL150244) outside of the submitted work. NZC reports receiving grants or contracts from Boston Children's Hospital and Cincinnati Children's Hospital and Medical Center outside of the submitted work. JCF reports receiving grants from the NIH outside of the submitted work. HD reports payments from Delex Pharma International Inc. outside of the submitted work. PMM reports receiving grants from the NIH and serving as a member of data safety monitoring board for the NIH supported KIDS-DOT trial outside of the submitted work. AGR reports receiving royalties from UpToDate outside of the submitted work. All other authors have nothing to declare., (© 2021 The Authors.)

Background: The assessment of real-world effectiveness of immunomodulatory medications for multisystem inflammatory syndrome in children (MIS-C) may guide therapy., Methods: We analyzed surveillance data on inpatients younger than 21 years of age who had MIS-C and were admitted to 1 of 58 U.S. hospitals between March 15 and October 31, 2020. The effectiveness of initial immunomodulatory therapy (day 0, indicating the first day any such therapy for MIS-C was given) with intravenous immune globulin (IVIG) plus glucocorticoids, as compared with IVIG alone, was evaluated with propensity-score matching and inverse probability weighting, with adjustment for baseline MIS-C severity and demographic characteristics. The primary outcome was cardiovascular dysfunction (a composite of left ventricular dysfunction or shock resulting in the use of vasopressors) on or after day 2. Secondary outcomes included the components of the primary outcome, the receipt of adjunctive treatment (glucocorticoids in patients not already receiving glucocorticoids on day 0, a biologic, or a second dose of IVIG) on or after day 1, and persistent or recurrent fever on or after day 2., Results: A total of 518 patients with MIS-C (median age, 8.7 years) received at least one immunomodulatory therapy; 75% had been previously healthy, and 9 died. In the propensity-score-matched analysis, initial treatment with IVIG plus glucocorticoids (103 patients) was associated with a lower risk of cardiovascular dysfunction on or after day 2 than IVIG alone (103 patients) (17% vs. 31%; risk ratio, 0.56; 95% confidence interval [CI], 0.34 to 0.94). The risks of the components of the composite outcome were also lower among those who received IVIG plus glucocorticoids: left ventricular dysfunction occurred in 8% and 17% of the patients, respectively (risk ratio, 0.46; 95% CI, 0.19 to 1.15), and shock resulting in vasopressor use in 13% and 24% (risk ratio, 0.54; 95% CI, 0.29 to 1.00). The use of adjunctive therapy was lower among patients who received IVIG plus glucocorticoids than among those who received IVIG alone (34% vs. 70%; risk ratio, 0.49; 95% CI, 0.36 to 0.65), but the risk of fever was unaffected (31% and 40%, respectively; risk ratio, 0.78; 95% CI, 0.53 to 1.13). The inverse-probability-weighted analysis confirmed the results of the propensity-score-matched analysis., Conclusions: Among children and adolescents with MIS-C, initial treatment with IVIG plus glucocorticoids was associated with a lower risk of new or persistent cardiovascular dysfunction than IVIG alone. (Funded by the Centers for Disease Control and Prevention.)., (Copyright © 2021 Massachusetts Medical Society.)

Importance: Refinement of criteria for multisystem inflammatory syndrome in children (MIS-C) may inform efforts to improve health outcomes., Objective: To compare clinical characteristics and outcomes of children and adolescents with MIS-C vs those with severe coronavirus disease 2019 (COVID-19)., Setting, Design, and Participants: Case series of 1116 patients aged younger than 21 years hospitalized between March 15 and October 31, 2020, at 66 US hospitals in 31 states. Final date of follow-up was January 5, 2021. Patients with MIS-C had fever, inflammation, multisystem involvement, and positive severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) reverse transcriptase-polymerase chain reaction (RT-PCR) or antibody test results or recent exposure with no alternate diagnosis. Patients with COVID-19 had positive RT-PCR test results and severe organ system involvement., Exposure: SARS-CoV-2., Main Outcomes and Measures: Presenting symptoms, organ system complications, laboratory biomarkers, interventions, and clinical outcomes. Multivariable regression was used to compute adjusted risk ratios (aRRs) of factors associated with MIS-C vs COVID-19., Results: Of 1116 patients (median age, 9.7 years; 45% female), 539 (48%) were diagnosed with MIS-C and 577 (52%) with COVID-19. Compared with patients with COVID-19, patients with MIS-C were more likely to be 6 to 12 years old (40.8% vs 19.4%; absolute risk difference [RD], 21.4% [95% CI, 16.1%-26.7%]; aRR, 1.51 [95% CI, 1.33-1.72] vs 0-5 years) and non-Hispanic Black (32.3% vs 21.5%; RD, 10.8% [95% CI, 5.6%-16.0%]; aRR, 1.43 [95% CI, 1.17-1.76] vs White). Compared with patients with COVID-19, patients with MIS-C were more likely to have cardiorespiratory involvement (56.0% vs 8.8%; RD, 47.2% [95% CI, 42.4%-52.0%]; aRR, 2.99 [95% CI, 2.55-3.50] vs respiratory involvement), cardiovascular without respiratory involvement (10.6% vs 2.9%; RD, 7.7% [95% CI, 4.7%-10.6%]; aRR, 2.49 [95% CI, 2.05-3.02] vs respiratory involvement), and mucocutaneous without cardiorespiratory involvement (7.1% vs 2.3%; RD, 4.8% [95% CI, 2.3%-7.3%]; aRR, 2.29 [95% CI, 1.84-2.85] vs respiratory involvement). Patients with MIS-C had higher neutrophil to lymphocyte ratio (median, 6.4 vs 2.7, P < .001), higher C-reactive protein level (median, 152 mg/L vs 33 mg/L; P < .001), and lower platelet count (<150 ×103 cells/μL [212/523 {41%} vs 84/486 {17%}, P < .001]). A total of 398 patients (73.8%) with MIS-C and 253 (43.8%) with COVID-19 were admitted to the intensive care unit, and 10 (1.9%) with MIS-C and 8 (1.4%) with COVID-19 died during hospitalization. Among patients with MIS-C with reduced left ventricular systolic function (172/503, 34.2%) and coronary artery aneurysm (57/424, 13.4%), an estimated 91.0% (95% CI, 86.0%-94.7%) and 79.1% (95% CI, 67.1%-89.1%), respectively, normalized within 30 days., Conclusions and Relevance: This case series of patients with MIS-C and with COVID-19 identified patterns of clinical presentation and organ system involvement. These patterns may help differentiate between MIS-C and COVID-19.

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.)., (Copyright © 2020 Massachusetts Medical Society.)

Data investigating the impact of household income and other factors on SV patient status-post-Fontan palliation after heart transplantation are lacking. We aim to evaluate factors affecting outcomes after OHT in this population. The PHIS database was interrogated for either SV or myocarditis/primary CM who were 4 years or older who underwent a single OHT. There were 1599 patients with a median age of 13.2 years (IQR: 9.3-16.1). Total hospital costs were significantly higher in the SV group ($408 000 vs $294 000, P < 0.0001), but as median household income increased, the risk of inhospital mortality, post-transplant LOS, and LOS-adjusted total hospital costs all decreased. The risk of inhospital mortality increased 6.5% per 1 year of age increase at the time of transplant. Patients in the SV group had significantly more diagnoses than those in the CM group (21 vs 15, P < 0.0001) and had longer total hospital LOSs as a result of longer post-transplant courses (25 days vs 15, P < 0.0001). Increased median household income and younger age are associated with decreased resource utilization and improved inhospital mortality in SV CHD patients who undergo OHT. In conclusion, earlier consideration of OHT in this population, coupled with improved selection criteria, may increase survival in this population., (© 2019 Wiley Periodicals, Inc.)