Hantavirus Pulmonary Syndrome in an Adolescent from North Dakota

Hantavirus pulmonary syndrome remains an uncommon yet emerging viral zoonosis that causes respiratory failure and hemodynamic instability in children and adolescents. Due to its acutely progressive course and high mortality rate, clinicians treating hantavirus pulmonary syndrome should understand its epidemiologic risk factors, clinical syndrome and radiographic findings. We present a case of hantavirus pulmonary syndrome in a 14-year-old female from North Dakota who survived the infection without sequelae.

Accuracy of Influenza ICD-10 Diagnosis Codes in Identifying Influenza Illness in Children

Importance

Studies of influenza in children commonly rely on coded diagnoses, yet the ability of International Classification of Diseases, Ninth Revision codes to identify influenza in the emergency department (ED) and hospital is highly variable. The accuracy of newer International Statistical Classification of Diseases and Related Health Problems, Tenth Revision (ICD-10) codes to identify influenza in children is unknown.

Objective

To determine the accuracy of ICD-10 influenza discharge diagnosis codes in the pediatric ED and inpatient settings.

Design, Setting, and Participants

Children younger than 18 years presenting to the ED or inpatient settings with fever and/or respiratory symptoms at 7 US pediatric medical centers affiliated with the Centers for Disease Control and Prevention-sponsored New Vaccine Surveillance Network from December 1, 2016, to March 31, 2020, were included in this cohort study. Nasal and/or throat swabs were collected for research molecular testing for influenza, regardless of clinical testing. Data, including ICD-10 discharge diagnoses and clinical testing for influenza, were obtained through medical record review. Data analysis was performed in August 2023.

Main Outcomes and Measures

The accuracy of ICD-10-coded discharge diagnoses was characterized using molecular clinical or research laboratory test results as reference. Measures included sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV). Estimates were stratified by setting (ED vs inpatient) and age (0-1, 2-4, and 5-17 years).

Results

A total of 16 867 children in the ED (median [IQR] age, 2.0 [0.0-4.0] years; 9304 boys [55.2%]) and 17 060 inpatients (median [IQR] age, 1.0 [0.0-4.0] years; 9798 boys [57.4%]) were included. In the ED, ICD-10 influenza diagnoses were highly specific (98.0%; 95% CI, 97.8%-98.3%), with high PPV (88.6%; 95% CI, 88.0%-89.2%) and high NPV (85.9%; 95% CI, 85.3%-86.6%), but sensitivity was lower (48.6%; 95% CI, 47.6%-49.5%). Among inpatients, specificity was 98.2% (95% CI, 98.0%-98.5%), PPV was 82.8% (95% CI, 82.1%-83.5%), sensitivity was 70.7% (95% CI, 69.8%-71.5%), and NPV was 96.5% (95% CI, 96.2%-96.9%). Accuracy of ICD-10 diagnoses varied by patient age, influenza season definition, time between disease onset and testing, and clinical setting.

Conclusions and Relevance

In this large cohort study, influenza ICD-10 discharge diagnoses were highly specific but moderately sensitive in identifying laboratory-confirmed influenza; the accuracy of influenza diagnoses varied by clinical and epidemiological factors. In the ED and inpatient settings, an ICD-10 diagnosis likely represents a true-positive influenza case.

Pre-existing Immunocompromising Conditions and Outcomes of Acute COVID-19 Patients Admitted for Pediatric Intensive Care

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

55 hospitals in 30 U.S. states reported cases through the Overcoming COVID-19 public health surveillance registry. Patients <21 years admitted March 12, 2020-December 30, 2021 to the pediatric intensive care unit (PICU) or high acuity unit for acute COVID-19 were included.

RESULTS

Of 1,274 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 = 0.005) and hospitalization was longer (p = 0.01) in patients with ICCs. New major morbidities upon discharge were not different between those with and without ICC (10.5% vs 13.9%, p = 0.40). In patients with ICC, bacterial co-infection 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.

Endemic coronavirus infections are associated with strong homotypic immunity in a US cohort of children from birth to 4 years

BACKGROUND

The endemic coronaviruses OC43, HKU1, NL63 and 229E cause cold-like symptoms and are related to SARS-CoV-2, but their natural histories are poorly understood. In a cohort of children followed from birth to 4 years, we documented all coronavirus infections, including SARS-CoV-2, to understand protection against subsequent infections with the same virus (homotypic immunity) or a different coronavirus (heterotypic immunity).

METHODS

Mother-child pairs were enrolled in metropolitan Cincinnati during the third trimester of pregnancy in 2017-18. Mothers reported their child's socio-demographics, risk factors, and weekly symptoms. Mid-turbinate nasal swabs were collected weekly. Blood was collected at 6 weeks, 6, 12, 18, 24 months and annually thereafter. Infections were detected by testing nasal swabs by an RT-PCR multi-pathogen panel and by serum IgG responses. Health care visits were documented from pediatric records. Analysis was limited to 116 children with high sample adherence. Re-consent for monitoring SARS-CoV-2 infections from June 2020 through November 2021 was obtained for 74 (64%) children.

RESULTS

We detected 345 endemic coronavirus infections (1.1 infections/child-year) and 21 SARS-CoV-2 infections (0.3 infections/child-year). Endemic coronavirus and SARS-CoV-2 infections were asymptomatic or mild. Significant protective homotypic immunity occurred after a single infection with OC43 (77%) and HKU1 (84%), and after two infections with NL63 (73%). No heterotypic protection against endemic coronaviruses or SARS-CoV-2 was identified.

CONCLUSIONS

Natural coronavirus infections were common and resulted in strong homotypic immunity but not heterotypic immunity against other coronaviruses, including SARS-CoV-2. Endemic coronavirus and SARS-CoV-2 infections in this US cohort were typically asymptomatic or mild.

Characteristics and Clinical Outcomes of Vaccine-Eligible US Children Under-5 Years Hospitalized for Acute COVID-19 in a National Network

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.

Respiratory Syncytial Virus-Associated Hospitalizations Among Children <5 Years Old: 2016 to 2020

BACKGROUND

Respiratory syncytial virus (RSV) is the leading cause of hospitalization in US infants. Accurate estimates of severe RSV disease inform policy decisions for RSV prevention.

METHODS

We conducted prospective surveillance for children <5 years old with acute respiratory illness from 2016 to 2020 at 7 pediatric hospitals. We interviewed parents, reviewed medical records, and tested midturbinate nasal ± throat swabs by reverse transcription polymerase chain reaction for RSV and other respiratory viruses. We describe characteristics of children hospitalized with RSV, risk factors for ICU admission, and estimate RSV-associated hospitalization rates.

RESULTS

Among 13 524 acute respiratory illness inpatients <5 years old, 4243 (31.4%) were RSV-positive; 2751 (64.8%) of RSV-positive children had no underlying condition or history of prematurity. The average annual RSV-associated hospitalization rate was 4.0 (95% confidence interval [CI]: 3.8-4.1) per 1000 children <5 years, was highest among children 0 to 2 months old (23.8 [95% CI: 22.5-25.2] per 1000) and decreased with increasing age. Higher RSV-associated hospitalization rates were found in premature versus term children (rate ratio = 1.95 [95% CI: 1.76-2.11]). Risk factors for ICU admission among RSV-positive inpatients included: age 0 to 2 and 3 to 5 months (adjusted odds ratio [aOR] = 1.97 [95% CI: 1.54-2.52] and aOR = 1.56 [95% CI: 1.18-2.06], respectively, compared with 24-59 months), prematurity (aOR = 1.32 [95% CI: 1.08-1.60]) and comorbid conditions (aOR = 1.35 [95% CI: 1.10-1.66]).

CONCLUSIONS

Younger infants and premature children experienced the highest rates of RSV-associated hospitalization and had increased risk of ICU admission. RSV prevention products are needed to reduce RSV-associated morbidity in young infants.

Interim Estimates of 2023-24 Seasonal Influenza Vaccine Effectiveness - United States

In the United States, annual influenza vaccination is recommended for all persons aged ≥6 months. Using data from four vaccine effectiveness (VE) networks during the 2023-24 influenza season, interim influenza VE was estimated among patients aged ≥6 months with acute respiratory illness-associated medical encounters using a test-negative case-control study design. Among children and adolescents aged 6 months-17 years, VE against influenza-associated outpatient visits ranged from 59% to 67% and against influenza-associated hospitalization ranged from 52% to 61%. Among adults aged ≥18 years, VE against influenza-associated outpatient visits ranged from 33% to 49% and against hospitalization from 41% to 44%. VE against influenza A ranged from 46% to 59% for children and adolescents and from 27% to 46% for adults across settings. VE against influenza B ranged from 64% to 89% for pediatric patients in outpatient settings and from 60% to 78% for all adults across settings. These findings demonstrate that the 2023-24 seasonal influenza vaccine is effective at reducing the risk for medically attended influenza virus infection. CDC recommends that all persons aged ≥6 months who have not yet been vaccinated this season get vaccinated while influenza circulates locally.

Correlates of Rotavirus Vaccine Shedding and Seroconversion in a U.S. Cohort of Healthy Infants

BACKGROUND

Rotavirus is a leading cause of severe pediatric gastroenteritis; two highly effective vaccines are used in the US. We aimed to identify correlates of immune response to rotavirus vaccination in a US cohort.

METHODS

PREVAIL is a birth cohort of 245 mother-child pairs enrolled 2017-2018 and followed for 2 years. Infant stool samples and symptom information were collected weekly. Shedding was defined as RT-PCR detection of rotavirus vaccine virus in stools collected 4-28 days after dose one. Seroconversion was defined as a threefold rise in IgA between the six-week and six-month blood draws. Correlates were analyzed using generalized estimating equations and logistic regression.

RESULTS

Pre-vaccination IgG (OR=0.84, 95% CI [0.75-0.94] per 100-unit increase) was negatively associated with shedding. Shedding was also less likely among infants with a single-nucleotide polymorphism inactivating FUT2 antigen secretion ("non-secretors") with non-secretor mothers, versus all other combinations (OR 0.37 [0.16-0.83]). Of 141 infants with data, 105 (74%) seroconverted; 78 (77%) had shed vaccine virus following dose one. Pre-vaccination IgG and secretor status were significantly associated with seroconversion. Neither shedding nor seroconversion significantly differed by vaccine product.

DISCUSSION

In this US cohort, pre-vaccination IgG and maternal and infant secretor status were associated with rotavirus vaccine response.

Maternal Vaccine Effectiveness Against Influenza-Associated Hospitalizations and Emergency Department Visits in Infants

Importance

Influenza virus infection during pregnancy is associated with severe maternal disease and may be associated with adverse birth outcomes. Inactivated influenza vaccine during pregnancy is safe and effective and can protect young infants, but recent evidence, particularly after the 2009 novel influenza A (H1N1) pandemic, is limited.

Objective

To evaluate the effectiveness of influenza vaccination during pregnancy against laboratory-confirmed influenza-associated hospitalizations and emergency department (ED) visits in infants younger than 6 months.

Design, Setting, and Participants

This was a prospective, test-negative case-control study using data from the New Vaccine Surveillance Network from the 2016 to 2017 through 2019 to 2020 influenza seasons. Infants younger than 6 months with an ED visit or hospitalization for acute respiratory illness were included from 7 pediatric medical institutions in US cities. Control infants with an influenza-negative molecular test were included for comparison. Data were analyzed from June 2022 to September 2023.

Exposure

Maternal influenza vaccination during pregnancy.

Main Outcomes and Measures

We estimated maternal vaccine effectiveness against hospitalizations or ED visits in infants younger than 6 months, those younger than 3 months, and by trimester of vaccination. Maternal vaccination status was determined using immunization information systems, medical records, or self-report. Vaccine effectiveness was estimated by comparing the odds of maternal influenza vaccination 14 days or more before delivery in infants with influenza vs those without.

Results

Of 3764 infants (223 with influenza and 3541 control infants), 2007 (53%) were born to mothers who were vaccinated during pregnancy. Overall vaccine effectiveness in infants was 34% (95% CI, 12 to 50), 39% (95% CI, 12 to 58) against influenza-associated hospitalizations, and 19% (95% CI, -24 to 48) against ED visits. Among infants younger than 3 months, effectiveness was 53% (95% CI, 30 to 68). Effectiveness was 52% (95% CI, 30 to 68) among infants with mothers who were vaccinated during the third trimester and 17% (95% CI, -15 to 40) among those with mothers who were vaccinated during the first or second trimesters.

Conclusions and Relevance

Maternal vaccination was associated with reduced odds of influenza-associated hospitalizations and ED visits in infants younger than 6 months. Effectiveness was greatest among infants younger than 3 months, for those born to mothers vaccinated during the third trimester, and against influenza-associated hospitalizations.

Obesity and Prenatal Intention as Predictors of Meeting Breastfeeding Recommendations in an Urban Birth Cohort

Background and Objectives: Few U.S. women meet the public health recommendations to exclusively breastfeed for 6 months and continue breastfeeding for at least 1-2 years. We compared prenatally collected demographic, health, and breastfeeding support/intention variables to examine how these factors intersect to predict meeting breastfeeding recommendations. Methods: PREVAIL, a CDC-funded birth cohort in Cincinnati, OH, was approved by the IRB at CDC, Cincinnati Children's Hospital, and the hospitals where enrollment (third trimester, 2017-2018) occurred. The prenatal questionnaire captured sociodemographics, pre-pregnancy weight and height, breastfeeding environment, and breastfeeding intention, while health factors were obtained from obstetrical records. Body mass index (BMI) (kg/m2) was categorized as healthy (18.5-24.9), overweight (25-29.9), obesity 1 (30-34.9), and obesity 2+ (≥35). Mothers self-reported date of exclusive and any breastfeeding cessation through quarterly postnatal questionnaires. Random forest was used for variable selection, cross-validated in multivariable logistic models. Results: Analysis included n = 237 mothers with BMI ≥18.5. Random forest identified BMI category, prenatal intention, and insurance type as the most important predictors of meeting breastfeeding recommendations. The resulting logistic models explained >40% of the variance with an area under the curve of ≥0.89 for both recommendations. More than 73% of the risk of not meeting breastfeeding recommendations was attributable to having an elevated BMI or lacking strong breastfeeding intention. Conclusions: In PREVAIL, maternal BMI and prenatal intention explained most risks of not meeting breastfeeding exclusivity and duration recommendations. Our findings suggest efforts to improve breastfeeding exclusivity and duration should focus on strengthening prenatal breastfeeding intention and identifying effective interventions for supporting breastfeeding among mothers with higher BMI.

Infants and young children generate more durable antibody responses to SARS-CoV-2 infection than adults

As SARS-CoV-2 becomes endemic, it is critical to understand immunity following early-life infection. We evaluated humoral responses to SARS-CoV-2 in 23 infants/young children. Antibody responses to SARS-CoV-2 spike antigens peaked approximately 30 days after infection and were maintained up to 500 days with little apparent decay. While the magnitude of humoral responses was similar to an adult cohort recovered from mild/moderate COVID-19, both binding and neutralization titers to WT SARS-CoV-2 were more durable in infants/young children, with spike and RBD IgG antibody half-life nearly 4X as long as in adults. IgG subtype analysis revealed that while IgG1 formed the majority of the response in both groups, IgG3 was more common in adults and IgG2 in infants/young children. These findings raise important questions regarding differential regulation of humoral immunity in infants/young children and adults and could have broad implications for the timing of vaccination and booster strategies in this age group.

Risk factors for health impairments in children after hospitalization for acute COVID-19 or MIS-C

Objective

To identify risk factors for persistent impairments after pediatric hospitalization for acute coronavirus disease 2019 (COVID-19) or multisystem inflammatory syndrome in children (MIS-C) during the SARS-CoV-2 pandemic.

Methods

Across 25 U.S. Overcoming COVID-19 Network hospitals, we conducted a prospective cohort study of patients <21-years-old hospitalized for acute COVID-19 or MIS-C (May 2020 to March 2022) surveyed 2- to 4-months post-admission. Multivariable regression was used to calculate adjusted risk ratios (aRR) and 95% confidence intervals (CI).

Results

Of 232 children with acute COVID-19, 71 (30.6%) had persistent symptoms and 50 (21.6%) had activity impairments at follow-up; for MIS-C (n = 241), 56 (23.2%) had persistent symptoms and 58 (24.1%) had activity impairments. In adjusted analyses of patients with acute COVID-19, receipt of mechanical ventilation was associated with persistent symptoms [aRR 1.83 (95% CI: 1.07, 3.13)] whereas obesity [aRR 2.18 (95% CI: 1.05, 4.51)] and greater organ system involvement [aRR 1.35 (95% CI: 1.13, 1.61)] were associated with activity impairment. For patients with MIS-C, having a pre-existing respiratory condition was associated with persistent symptoms [aRR 3.04 (95% CI: 1.70, 5.41)] whereas obesity [aRR 1.86 (95% CI: 1.09, 3.15)] and greater organ system involvement [aRR 1.26 (1.00, 1.58)] were associated with activity impairments.

Discussion

Among patients hospitalized, nearly one in three hospitalized with acute COVID-19 and one in four hospitalized with MIS-C had persistent impairments for ≥2 months post-hospitalization. Persistent impairments were associated with more severe illness and underlying health conditions, identifying populations to target for follow-up.

Multi-omics analysis of mucosal and systemic immunity to SARS-CoV-2 after birth

The dynamics of immunity to infection in infants remain obscure. Here, we used a multi-omics approach to perform a longitudinal analysis of immunity to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in infants and young children by analyzing blood samples and weekly nasal swabs collected before, during, and after infection with Omicron and non-Omicron variants. Infection stimulated robust antibody titers that, unlike in adults, showed no sign of decay for up to 300 days. Infants mounted a robust mucosal immune response characterized by inflammatory cytokines, interferon (IFN) α, and T helper (Th) 17 and neutrophil markers (interleukin [IL]-17, IL-8, and CXCL1). The immune response in blood was characterized by upregulation of activation markers on innate cells, no inflammatory cytokines, but several chemokines and IFNα. The latter correlated with viral load and expression of interferon-stimulated genes (ISGs) in myeloid cells measured by single-cell multi-omics. Together, these data provide a snapshot of immunity to infection during the initial weeks and months of life.

Effectiveness of Maternal mRNA COVID-19 Vaccination During Pregnancy Against COVID-19-Associated Hospitalizations in Infants Aged <6 Months During SARS-CoV-2 Omicron Predominance - 20 States, March 9, 2022-May 31, 2023

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.

Surveillance for Multisystem Inflammatory Syndrome in US Children Aged 5-11 Years Who Received Pfizer-BioNTech COVID-19 Vaccine, November 2021 through March 2022

Multisystem inflammatory syndrome in children (MIS-C) is a complication of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection; in the United States, reporting of MIS-C after coronavirus disease 2019 (COVID-19) vaccination is required for vaccine safety monitoring. Pfizer-BioNTech COVID-19 vaccine was authorized for children aged 5-11 years on 29 October 2021. Covering a period when approximately 7 million children received vaccine, surveillance for MIS-C ≤ 90 days postvaccination using passive systems identified 58 children with MIS-C and laboratory evidence of past/recent SARS-CoV-2 infection, and 4 without evidence. During a period with extensive SARS-CoV-2 circulation, MIS-C illness in children after COVID-19 vaccination who lacked evidence of SARS-CoV-2 infection was rare (<1 per million vaccinated children).

Immunogenicity of adjuvanted versus high-dose inactivated influenza vaccines in older adults: a randomized clinical trial

BACKGROUND

Adjuvanted inactivated influenza vaccine (aIIV) and high-dose inactivated influenza vaccine (HD-IIV) are U.S.-licensed for adults aged ≥ 65 years. This study compared serum hemagglutination inhibition (HAI) antibody titers for the A(H3N2) and A(H1N1)pdm09 and B strains after trivalent aIIV3 and trivalent HD-IIV3 in an older adult population.

RESULTS

The immunogenicity population included 342 participants who received aIIV3 and 338 participants who received HD-IIV3. The proportion of participants that seroconverted to A(H3N2) vaccine strains after allV3 (112 participants [32.8%]) was inferior to the proportion of participants that seroconverted after HD-IIV3 (130 participants [38.5%]) at day 29 after vaccination (difference, - 5.8%; 95%CI, - 12.9% to 1.4%). There were no significant differences between the vaccine groups in percent seroconversion to A(H1N1)pdm09 or B vaccine strains, in percent seropositivity for any of the strains, or in post-vaccination GMT for the A(H1N1)pdm09 strain. The GMTs for the post-vaccination A(H3N2) and B strains were higher after HD-IIV than after aIIV3.

CONCLUSIONS

Overall immune responses were similar after aIIV3 and HD-IIV3. For the primary outcome, the aIIV3 seroconversion rate for H3N2 did not meet noninferiority criteria compared with HD-IIV3, but the HD-IIV3 seroconversion rate was not statistically superior to the aIIV3 seroconversion rate.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier: NCT03183908.

Prenatal SARS-CoV-2 infection alters postpartum human milk-derived extracellular vesicles

Human milk-derived extracellular vesicles (HMEVs) are crucial functional components in breast milk, contributing to infant health and development. Maternal conditions could affect HMEV cargos; however, the impact of SARS-CoV-2 infection on HMEVs remains unknown. This study evaluated the influence of SARS-CoV-2 infection during pregnancy on postpartum HMEV molecules. Milk samples (9 prenatal SARS-CoV-2 vs. 9 controls) were retrieved from the IMPRINT birth cohort. After defatting and casein micelle disaggregation, 1 mL milk was subjected to a sequential process of centrifugation, ultrafiltration, and qEV-size exclusion chromatography. Particle and protein characterizations were performed following the MISEV2018 guidelines. EV lysates were analyzed through proteomics and miRNA sequencing, while the intact EVs were biotinylated for surfaceomic analysis. Multi-Omics was employed to predict HMEV functions associated with prenatal SARS-CoV-2 infection. Demographic data between the prenatal SARS-CoV-2 and control groups were similar. The median duration from maternal SARS-CoV-2 test positivity to milk collection was 3 months (range: 1-6 months). Transmission electron microscopy showed the cup-shaped nanoparticles. Nanoparticle tracking analysis demonstrated particle diameters of <200 nm and yields of >1e11 particles from 1 mL milk. Western immunoblots detected ALIX, CD9 and HSP70, supporting the presence of HMEVs in the isolates. Thousands of HMEV cargos and hundreds of surface proteins were identified and compared. Multi-Omics predicted that mothers with prenatal SARS-CoV-2 infection produced HMEVs with enhanced functionalities involving metabolic reprogramming and mucosal tissue development, while mitigating inflammation and lower EV transmigration potential. Our findings suggest that SARS-CoV-2 infection during pregnancy boosts mucosal site-specific functions of HMEVs, potentially protecting infants against viral infections. Further prospective studies should be pursued to reevaluate the short- and long-term benefits of breastfeeding in the post-COVID era.

Evaluation of association of anti-PEG antibodies with anaphylaxis after mRNA COVID-19 vaccination

BACKGROUND

The mechanism for anaphylaxis following mRNA COVID-19 vaccination has been widely debated; understanding this serious adverse event is important for future vaccines of similar design. A mechanism proposed is type I hypersensitivity (i.e., IgE-mediated mast cell degranulation) to polyethylene glycol (PEG). Using an assay that, uniquely, had been previously assessed in patients with anaphylaxis to PEG, our objective was to compare anti-PEG IgE in serum from mRNA COVID-19 vaccine anaphylaxis case-patients and persons vaccinated without allergic reactions. Secondarily, we compared anti-PEG IgG and IgM to assess alternative mechanisms.

METHODS

Selected anaphylaxis case-patients reported to U.S. Vaccine Adverse Event Reporting System December 14, 2020-March 25, 2021 were invited to provide a serum sample. mRNA COVID-19 vaccine study participants with residual serum and no allergic reaction post-vaccination ("controls") were frequency matched to cases 3:1 on vaccine and dose number, sex and 10-year age category. Anti-PEG IgE was measured using a dual cytometric bead assay (DCBA). Anti-PEG IgG and IgM were measured using two different assays: DCBA and a PEGylated-polystyrene bead assay. Laboratorians were blinded to case/control status.

RESULTS

All 20 case-patients were women; 17 had anaphylaxis after dose 1, 3 after dose 2. Thirteen (65 %) were hospitalized and 7 (35 %) were intubated. Time from vaccination to serum collection was longer for case-patients vs controls (post-dose 1: median 105 vs 21 days). Among Moderna recipients, anti-PEG IgE was detected in 1 of 10 (10 %) case-patients vs 8 of 30 (27 %) controls (p = 0.40); among Pfizer-BioNTech recipients, it was detected in 0 of 10 case-patients (0 %) vs 1 of 30 (3 %) controls (p >n 0.99). Anti-PEG IgE quantitative signals followed this same pattern. Neither anti-PEG IgG nor IgM was associated with case status with both assay formats.

CONCLUSION

Our results support that anti-PEG IgE is not a predominant mechanism for anaphylaxis post-mRNA COVID-19 vaccination.

Novel paradigm enables accurate monthly gestational screening to prevent congenital toxoplasmosis and more

Background

Congenital toxoplasmosis is a treatable, preventable disease, but untreated causes death, prematurity, loss of sight, cognition and motor function, and substantial costs worldwide.

Methods/Findings

In our ongoing USA feasibility/efficacy clinical trial, data collated with other ongoing and earlier published results proved high performance of an Immunochromatographic-test(ICT) that enables accurate, rapid diagnosis/treatment, establishing new paradigms for care. Overall results from patient blood and/or serum samples tested with ICT compared with gold-standard-predicate-test results found ICT performance for 4606 sera/1876 blood, 99.3%/97.5% sensitive and 98.9%/99.7% specific. However, in the clinical trial the FDA-cleared-predicate test initially caused practical, costly problems due to false-positive-IgM results. For 58 persons, 3/43 seronegative and 2/15 chronically infected persons had false positive IgM predicate tests. This caused substantial anxiety, concerns, and required costly, delayed confirmation in reference centers. Absence of false positive ICT results contributes to solutions: Lyon and Paris France and USA Reference laboratories frequently receive sera with erroneously positive local laboratory IgM results impeding patient care. Therefore, thirty-two such sera referred to Lyon's Reference laboratory were ICT-tested. We collated these with other earlier/ongoing results: 132 of 137 USA or French persons had false positive local laboratory IgM results identified correctly as negative by ICT. Five false positive ICT results in Tunisia and Marseille, France, emphasize need to confirm positive ICT results with Sabin-Feldman-Dye-test or western blot. Separate studies demonstrated high performance in detecting acute infections, meeting FDA, CLIA, WHO ASSURED, CEMark criteria and patient and physician satisfaction with monthly-gestational-ICT-screening.

Conclusions/Significance

This novel paradigm using ICT identifies likely false positives or raises suspicion that a result is truly positive, rapidly needing prompt follow up and treatment. Thus, ICT enables well-accepted gestational screening programs that facilitate rapid treatment saving lives, sight, cognition and motor function. This reduces anxiety, delays, work, and cost at point-of-care and clinical laboratories.

Author’s Summary

Toxoplasmosis is a major health burden for developed and developing countries, causing damage to eyes and brain, loss of life and substantial societal costs. Prompt diagnosis in gestational screening programs enables treatment, thereby relieving suffering, and leading to > 14-fold cost savings for care. Herein, we demonstrate that using an ICT that meets WHO ASSURED-criteria identifying persons with/without antibody to Toxoplasma gondii in sera and whole blood with high sensitivity and specificity, is feasible to use in USA clinical practice. We find this new approach can help to obviate the problem of detection of false positive anti- T.gondii IgM results for those without IgG antibodies to T.gondii when this occurs in present, standard of care, predicate USA FDA cleared available assays. Thus, this accurate test facilitates gestational screening programs and a global initiative to diagnose and thereby prevent and treat T.gondii infection. This minimizes likelihood of false positives (IgG and/or IgM) while maintaining maximum sensitivity. When isolated IgM antibodies are detected, it is necessary to confirm and when indicated continue follow up testing in ∼2 weeks to establish seroconversion. Presence of a positive ICT makes it likely that IgM is truly positive and a negative ICT makes it likely that IgM will be a false positive without infection. These results create a new, enthusiastically-accepted, precise paradigm for rapid diagnosis and validation of results with a second-line test. This helps eliminate alarm and anxiety about false-positive results, while expediting needed treatment for true positive results and providing back up distinguishing false positive tests.

Infants and young children generate more durable antibody responses to SARS-CoV-2 infection than adults

Since the emergence of SARS-CoV-2, research has shown that adult patients mount broad and durable immune responses to infection. However, response to infection remains poorly studied in infants/young children. In this study, we evaluated humoral responses to SARS-CoV-2 in 23 infants/young children before and after infection. We found that antibody responses to SARS-CoV-2 spike antigens peaked approximately 30 days after infection and were maintained up to 500 days with little apparent decay. While the magnitude of humoral responses was similar to an adult cohort recovered from mild/moderate COVID-19, both binding and neutralization titers to WT SARS-CoV-2 were more durable in infants/young children, with Spike and RBD IgG antibody half-life nearly 4X as long as in adults. The functional breadth of adult and infant/young children SARS-CoV-2 responses were comparable, with similar reactivity against panel of recent and previously circulating viral variants. Notably, IgG subtype analysis revealed that while IgG1 formed the majority of both adults' and infants/young children's response, IgG3 was more common in adults and IgG2 in infants/young children. These findings raise important questions regarding differential regulation of humoral immunity in infants/young children and adults and could have broad implications for the timing of vaccination and booster strategies in this age group.

NFKB2 haploinsufficiency identified via screening for IFN-α2 autoantibodies in children and adolescents hospitalized with SARS-CoV-2-related complications

BACKGROUND

Autoantibodies against type I IFNs occur in approximately 10% of adults with life-threatening coronavirus disease 2019 (COVID-19). The frequency of anti-IFN autoantibodies in children with severe sequelae of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection is unknown.

OBJECTIVE

We quantified anti-type I IFN autoantibodies in a multicenter cohort of children with severe COVID-19, multisystem inflammatory syndrome in children (MIS-C), and mild SARS-CoV-2 infections.

METHODS

Circulating anti-IFN-α2 antibodies were measured by a radioligand binding assay. Whole-exome sequencing, RNA sequencing, and functional studies of peripheral blood mononuclear cells were used to study any patients with levels of anti-IFN-α2 autoantibodies exceeding the assay's positive control.

RESULTS

Among 168 patients with severe COVID-19, 199 with MIS-C, and 45 with mild SARS-CoV-2 infections, only 1 had high levels of anti-IFN-α2 antibodies. Anti-IFN-α2 autoantibodies were not detected in patients treated with intravenous immunoglobulin before sample collection. Whole-exome sequencing identified a missense variant in the ankyrin domain of NFKB2, encoding the p100 subunit of nuclear factor kappa-light-chain enhancer of activated B cells, aka NF-κB, essential for noncanonical NF-κB signaling. The patient's peripheral blood mononuclear cells exhibited impaired cleavage of p100 characteristic of NFKB2 haploinsufficiency, an inborn error of immunity with a high prevalence of autoimmunity.

CONCLUSIONS

High levels of anti-IFN-α2 autoantibodies in children and adolescents with MIS-C, severe COVID-19, and mild SARS-CoV-2 infections are rare but can occur in patients with inborn errors of immunity.

Community-Onset Bacterial Coinfection in Children Critically Ill With Severe Acute Respiratory Syndrome Coronavirus 2 Infection

Background

Community-onset bacterial coinfection in adults hospitalized with coronavirus disease 2019 (COVID-19) is reportedly uncommon, though empiric antibiotic use has been high. However, data regarding empiric antibiotic use and bacterial coinfection in children with critical illness from COVID-19 are scarce.

Methods

We evaluated children and adolescents aged <19 years admitted to a pediatric intensive care or high-acuity unit for COVID-19 between March and December 2020. Based on qualifying microbiology results from the first 3 days of admission, we adjudicated whether patients had community-onset bacterial coinfection. We compared demographic and clinical characteristics of those who did and did not (1) receive antibiotics and (2) have bacterial coinfection early in admission. Using Poisson regression models, we assessed factors associated with these outcomes.

Results

Of the 532 patients, 63.3% received empiric antibiotics, but only 7.1% had bacterial coinfection, and only 3.0% had respiratory bacterial coinfection. In multivariable analyses, empiric antibiotics were more likely to be prescribed for immunocompromised patients (adjusted relative risk [aRR], 1.34 [95% confidence interval {CI}, 1.01-1.79]), those requiring any respiratory support except mechanical ventilation (aRR, 1.41 [95% CI, 1.05-1.90]), or those requiring invasive mechanical ventilation (aRR, 1.83 [95% CI, 1.36-2.47]) (compared with no respiratory support). The presence of a pulmonary comorbidity other than asthma (aRR, 2.31 [95% CI, 1.15-4.62]) was associated with bacterial coinfection.

Conclusions

Community-onset bacterial coinfection in children with critical COVID-19 is infrequent, but empiric antibiotics are commonly prescribed. These findings inform antimicrobial use and support rapid de-escalation when evaluation shows coinfection is unlikely.

Circulation of Rhinoviruses and/or Enteroviruses in Pediatric Patients With Acute Respiratory Illness Before and During the COVID-19 Pandemic in the US

IMPORTANCE

Rhinoviruses and/or enteroviruses, which continued to circulate during the COVID-19 pandemic, are commonly detected in pediatric patients with acute respiratory illness (ARI). Yet detailed characterization of rhinovirus and/or enterovirus detection over time is limited, especially by age group and health care setting.

OBJECTIVE

To quantify and characterize rhinovirus and/or enterovirus detection before and during the COVID-19 pandemic among children and adolescents seeking medical care for ARI at emergency departments (EDs) or hospitals.

DESIGN, SETTING, AND PARTICIPANTS

This cross-sectional study used data from the New Vaccine Surveillance Network (NVSN), a multicenter, active, prospective surveillance platform, for pediatric patients who sought medical care for fever and/or respiratory symptoms at 7 EDs or hospitals within NVSN across the US between December 2016 and February 2021. Persons younger than 18 years were enrolled in NVSN, and respiratory specimens were collected and tested for multiple viruses.

MAIN OUTCOMES AND MEASURES

Proportion of patients in whom rhinovirus and/or enterovirus, or another virus, was detected by calendar month and by prepandemic (December 1, 2016, to March 11, 2020) or pandemic (March 12, 2020, to February 28, 2021) periods. Month-specific adjusted odds ratios (aORs) for rhinovirus and/or enterovirus-positive test results (among all tested) by setting (ED or inpatient) and age group (<2, 2-4, or 5-17 years) were calculated, comparing each month during the pandemic to equivalent months of previous years.

RESULTS

Of the 38 198 children and adolescents who were enrolled and tested, 11 303 (29.6%; mean [SD] age, 2.8 [3.7] years; 6733 boys [59.6%]) had rhinovirus and/or enterovirus-positive test results. In prepandemic and pandemic periods, rhinoviruses and/or enteroviruses were detected in 29.4% (9795 of 33 317) and 30.9% (1508 of 4881) of all patients who were enrolled and tested and in 42.2% (9795 of 23 236) and 73.0% (1508 of 2066) of those with test positivity for any virus, respectively. Rhinoviruses and/or enteroviruses were the most frequently detected viruses in both periods and all age groups in the ED and inpatient setting. From April to September 2020 (pandemic period), rhinoviruses and/or enteroviruses were detectable at similar or lower odds than in prepandemic years, with aORs ranging from 0.08 (95% CI, 0.04-0.19) to 0.76 (95% CI, 0.55-1.05) in the ED and 0.04 (95% CI, 0.01-0.11) to 0.71 (95% CI, 0.47-1.07) in the inpatient setting. However, unlike some other viruses, rhinoviruses and/or enteroviruses soon returned to prepandemic levels and from October 2020 to February 2021 were detected at similar or higher odds than in prepandemic months in both settings, with aORs ranging from 1.47 (95% CI, 1.12-1.93) to 3.01 (95% CI, 2.30-3.94) in the ED and 1.36 (95% CI, 1.03-1.79) to 2.44 (95% CI, 1.78-3.34) in the inpatient setting, and in all age groups. Compared with prepandemic years, during the pandemic, rhinoviruses and/or enteroviruses were detected in patients who were slightly older, although most (74.5% [1124 of 1508]) were younger than 5 years.

CONCLUSIONS AND RELEVANCE

Results of this study show that rhinoviruses and/or enteroviruses persisted and were the most common respiratory virus group detected across all pediatric age groups and in both ED and inpatient settings. Rhinoviruses and/or enteroviruses remain a leading factor in ARI health care burden, and active ARI surveillance in children and adolescents remains critical for defining the health care burden of respiratory viruses.

Systems biological assessment of the temporal dynamics of immunity to a viral infection in the first weeks and months of life

The dynamics of innate and adaptive immunity to infection in infants remain obscure. Here, we used a multi-omics approach to perform a longitudinal analysis of immunity to SARS-CoV-2 infection in infants and young children in the first weeks and months of life by analyzing blood samples collected before, during, and after infection with Omicron and Non-Omicron variants. Infection stimulated robust antibody titers that, unlike in adults, were stably maintained for >300 days. Antigen-specific memory B cell (MCB) responses were durable for 150 days but waned thereafter. Somatic hypermutation of V-genes in MCB accumulated progressively over 9 months. The innate response was characterized by upregulation of activation markers on blood innate cells, and a plasma cytokine profile distinct from that seen in adults, with no inflammatory cytokines, but an early and transient accumulation of chemokines (CXCL10, IL8, IL-18R1, CSF-1, CX3CL1), and type I IFN. The latter was strongly correlated with viral load, and expression of interferon-stimulated genes (ISGs) in myeloid cells measured by single-cell transcriptomics. Consistent with this, single-cell ATAC-seq revealed enhanced accessibility of chromatic loci targeted by interferon regulatory factors (IRFs) and reduced accessibility of AP-1 targeted loci, as well as traces of epigenetic imprinting in monocytes, during convalescence. Together, these data provide the first snapshot of immunity to infection during the initial weeks and months of life.

Gut Microbiome Composition and Metabolic Capacity Differ by FUT2 Secretor Status in Exclusively Breastfed Infants

A major polymorphism in the fucosyltransferase2 (FUT2) gene influences risk of multiple gut diseases, but its impact on the microbiome of breastfed infants was unknown. In individuals with an active FUT2 enzyme (“secretors”), the intestinal mucosa is abundantly fucosylated, providing mutualist bacteria with a rich endogenous source of fucose. Non-secretors comprise approximately one-fifth of the population, and they lack the ability to create this enzyme. Similarly, maternal secretor status influences the abundance of a breastfeeding mother’s fucosylated milk oligosaccharides. We compared the impact of maternal secretor status, measured by FUT2 genotype, and infant secretor status, measured by FUT2 genotype and phenotype, on early infant fecal microbiome samples collected from 2-month-old exclusively breastfed infants (n = 59). Infant secretor status (19% non-secretor, 25% low-secretor, and 56% full-secretor) was more strongly associated with the infant microbiome than it was with the maternal FUT2 genotype. Alpha diversity was greater in the full-secretors than in the low- or non-secretor infants (p = 0.049). Three distinct microbial enterotypes corresponded to infant secretor phenotype (p = 0.022) and to the dominance of Bifidobacterium breve, B. longum, or neither (p < 0.001). Infant secretor status was also associated with microbial metabolic capacity, specifically, bioenergetics pathways. We concluded that in exclusively breastfed infants, infant—but not maternal—secretor status is associated with infant microbial colonization and metabolic capacity.

2196. Frequencies of Adenovirus Types in U.S. Children with Acute Respiratory Illness, 2016–2019

Background

Adenovirus (AdV) is a common cause of acute respiratory illness (ARI). Multiple respiratory AdV types have been identified in humans, but it remains unclear which are the most common in U.S. children with ARI.

Methods

We conducted a multicenter, prospective viral surveillance study at seven U.S. children’s hospitals, the New Vaccine Surveillance Network, during 12/1/16–11/30/19, prior to the COVID-19 pandemic. Children < 18 years of age seen in the emergency department or hospitalized with fever and/or respiratory symptoms were enrolled, and mid-turbinate nasal +/- throat swabs were tested using multiplex respiratory pathogen assays or real time polymerase chain reaction (PCR) test for AdV, respiratory syncytial virus (RSV), human metapneumovirus, rhinovirus/enterovirus (RV), influenza, parainfluenza viruses, and endemic coronaviruses. AdV-positive specimens were subsequently typed using single-plex qPCR assays targeting sequences in the hexon gene specific for types 1-7, 11, 14, 16 and 21. Demographics, clinical characteristics, and outcomes were compared between AdV types.

Results

Of 29,381 enrolled children, 2,106 (7.2%) tested positive for AdV. The distribution of types among the 1,330 (63.2%) successfully typed specimens were as follows: 31.7% AdV-2, 28.9% AdV-1, 15.3% AdV-3, 7.9% AdV-5, 5.9% AdV-7, 1.4% AdV-4, 1.2% AdV-6, 0.5% AdV-14, 0.2% AdV-21, 0.1% AdV-11, and 7.0% ≥1 AdV type. Most children with AdV-1 or AdV-2 detection were < 5 years of age (Figure 1a). Demographic and clinical characteristics varied by AdV types, including age, race/ethnicity, smoke exposure, daycare/school attendance, and hospitalization (Table 1). Co-detection with other viruses was common among all AdV types, with RV and RSV being the most frequently co-detected (Figure 1b). Fever and cough were the most common symptoms for all AdV types (Figure 2). Children with AdV-7 detected as single pathogen had higher odds of hospitalization (adjusted odds ratio 6.34 [95% CI: 3.10, 12.95], p= 0.027).

Conclusion

AdV-2 and AdV-1 were the most frequently detected AdV types among children over the 3-year study period. Notable clinical heterogeneity of the AdV types warrants further surveillance studies to identify AdV types that could be targeted for pediatric vaccine development.

Disclosures

Rangaraj Selvarangan, BVSc, PhD, D(ABMM), FIDSA, F(AAM), BioFire: Grant/Research Support|Luminex: Grant/Research Support John Williams, MD, GlaxoSmithKline: Advisor/Consultant|Quidel: Advisor/Consultant Mary A. Staat, MD, MPH, Centers for Disease Control and Prevention: Grant/Research Support|Cepheid: Grant/Research Support|National Institute of Health: Grant/Research Support|Uptodate: Royalties Christopher J Harrison, MD, Astellas: Grant/Research Support|GSK: Grant/Research Support|Merck: Grant/Research Support|Pediatric news: Honoraria|Pfizer: Grant/Research Support Mary E. Moffatt, M.D., Becton and Dickinson and Company: Stocks/Bonds|Biogen: Stocks/Bonds|Coloplast B: Stocks/Bonds|Express Scripts: Stocks/Bonds|Novo Nordisk A/S Spons ADR: Stocks/Bonds|Novo Nordisk A/S-B: Stocks/Bonds|Steris PLC: Stocks/Bonds|Stryker Corp: Stocks/Bonds|Thermo Fisher Scientific: Stocks/Bonds Geoffrey A. Weinberg, MD, Merck & Co.: Honoraria|Merck & Co.: Honoraria for composing and reviewing textbook chapters, Merck Manual of Therapeutics Janet A. Englund, MD, AstraZeneca: Advisor/Consultant|AstraZeneca: Grant/Research Support|GlaxoSmithKline: Grant/Research Support|Meissa Vaccines: Advisor/Consultant|Merck: Grant/Research Support|Pfizer: Grant/Research Support|Sanofi Pasteur: Advisor/Consultant Natasha B. Halasa, MD, Quidel: Grant/Research Support|Quidel: equipment donation|Sanofi: Grant/Research Support|Sanofi: HAI testing and vaccine donation.

92. Incidence of Adenovirus Respiratory Infection and Coinfection in a Longitudinal Birth Cohort

Background

Adenoviruses (AdVs) are a common cause of acute respiratory illness (ARI) in children and are often detected with other viruses (coinfection). However, the community incidence of AdV infections is poorly understood due to a lack of prospective studies outside the hospital setting. Here, we aim to characterize respiratory AdV infections and coinfections in a prospective birth cohort of children.

Methods

The PREVAIL cohort is a CDC-funded, 2-year birth cohort, conducted from 2017–2020 in Cincinnati, OH. ARI was defined as the presence of cough or fever identified with weekly maternal text surveys and medical chart review. Mid-turbinate nasal swabs were collected weekly. Swabs were tested using Luminex Respiratory Pathogen Panel. AdV infection was defined as a swab positive for AdV and included subsequent positives < 30 days apart. Coinfection was defined as detection of any other virus(es) during an AdV infection. Children who submitted at least 70% of weekly samples were included in our analysis.

Results

101 children met inclusion criteria, representing 165 child-years. 137 distinct AdV infections were identified (incidence 0.84 infections per child year), with 98 (97%) children having ≥1 AdV infection. Only 40% (n=55) of AdV infections were symptomatic. Of those with symptomatic infections, 51% (n=28) sought medical care, with 42% (n=23) presenting to a primary care provider and 9% (n=5) resulting in an ED visit or hospital admission. Coinfections were detected in 67% (n=92) of AdV infections, with 45% (n=62) coinfected with 1 virus, 19% (n=26) with 2 viruses, and 3% (n=4) with ≥3 viruses. 77% of coinfections (n=71) were rhino/enterovirus. The number of coinfections or the specific coinfection virus was not associated with an increase in symptom prevalence or symptom severity (all p > 0.05).

Viral Coinfection Frequency with Adenovirus Infection in the PREVAIL Cohort.

Adenovirus Infection and Coinfection in the PREVAIL Cohort.

Conclusion

In this cohort of healthy children, AdVs were a common cause of respiratory infection. Most infections were asymptomatic or resulted in mild symptoms. Two-thirds of AdV infections involved viral coinfections, but coinfection was not associated with more frequent or severe symptoms. Our findings suggest studies that only include symptomatic or hospitalized patients may overestimate AdVs disease severity.

Disclosures

All Authors: No reported disclosures.

2167. Use and Timing of Antiviral Therapy for Influenza in Hospitalized U.S. Children, 2016–2020

Background

According to the 2018 Infectious Diseases Society of America (IDSA) clinical practice guidelines and Centers for Disease Control and Prevention (CDC) guidance, clinicians should start antiviral treatment as soon as possible for children who are hospitalized with suspected or confirmed influenza. We assessed the use of influenza-specific antiviral therapy in children hospitalized with symptoms of acute respiratory illness and laboratory-confirmed influenza.

Methods

We conducted active, population-based surveillance of children hospitalized with fever and/or respiratory symptoms (12/01/2016–02/28/2020) at the seven U.S. medical centers that comprise the CDC New Vaccine Surveillance Network. We excluded children who did not undergo clinical testing (by rapid antigen testing or nucleic acid amplification test [NAAT]) or research testing (by NAAT) for influenza, those who presented out of influenza season (site- and season-specific), and those whose date of antiviral therapy or whether antiviral therapy was given was unknown. We assessed the use of influenza-specific antiviral therapy in this cohort and defined timely antiviral therapy as administration within 2 days of hospitalization.

Results

Of 11,275 eligible children, 1,149 (10.2%) tested positive for influenza by clinical and/or research assays (Table 1). Overall, 154 influenza cases (13.4%) were detected by clinical testing only, 428 (37.2%) by research testing only, and 567 (49.3%) by both. During their influenza-associated hospitalization, 620 children (54.0%) received influenza-specific antivirals, and therapy was timely in 572 cases (92.3%). Of those who tested positive clinically, 445/721 (61.7%) received timely antiviral therapy, 38 (5.3%) received delayed antiviral therapy, and 238 (33.0%) received no antiviral therapy. Oseltamivir was the antiviral used in all treated cases. The distribution of antiviral-treated cases varied by race and Hispanic origin and study site, but not by age at presentation or influenza season (Figure 1). Table 1

Demographic characteristics of 1,149 children with influenza enrolled in the New Vaccine Surveillance Network over four influenza seasons between December 1, 2016, and February 28, 2020. Figure 1Proportions of children with influenza enrolled in the New Vaccine Surveillance Network who received timely, delayed, or no antiviral therapy by age at presentation, race and Hispanic origin, study site, and influenza season (N=1,149).

Conclusion

Although antiviral therapy is recommended for all influenza-associated hospitalizations in children, antiviral prescribing remains suboptimal. Further studies would help identify and address barriers to antiviral therapy in children with influenza.

Disclosures

John Williams, MD, GlaxoSmithKline: Advisor/Consultant|Quidel: Advisor/Consultant Janet A. Englund, MD, AstraZeneca: Advisor/Consultant|AstraZeneca: Grant/Research Support|GlaxoSmithKline: Grant/Research Support|Meissa Vaccines: Advisor/Consultant|Merck: Grant/Research Support|Pfizer: Grant/Research Support|Sanofi Pasteur: Advisor/Consultant Rangaraj Selvarangan, BVSc, PhD, D(ABMM), FIDSA, F(AAM), BioFire: Grant/Research Support|Luminex: Grant/Research Support Mary A. Staat, MD, MPH, Centers for Disease Control and Prevention: Grant/Research Support|Cepheid: Grant/Research Support|National Institute of Health: Grant/Research Support|Uptodate: Royalties Geoffrey A. Weinberg, MD, Merck & Co.: Honoraria|Merck & Co.: Honoraria for composing and reviewing textbook chapters, Merck Manual of Therapeutics Flor M. Munoz, MD, MSc, Gilead: Grant/Research Support|Moderna: DSMB|Pfizer: DSMB Christopher J Harrison, MD, Astellas: Grant/Research Support|GSK: Grant/Research Support|Merck: Grant/Research Support|Pediatric news: Honoraria|Pfizer: Grant/Research Support Natasha B. Halasa, MD, Quidel: Grant/Research Support|Quidel: equipment donation|Sanofi: Grant/Research Support|Sanofi: HAI testing and vaccine donation.

95. Prolonged respiratory viral infection associated with presence of coinfections in an urban birth cohort

Background

Prolonged infection by respiratory viruses has been reported, especially in hospitalized or immunocompromised children. However, little is known of factors contributing to prolonged respiratory viral infection, particularly in asymptomatic and less severe infections. We examined characteristics associated with prolonged viral infection in a community-based birth cohort.

Methods

The PREVAIL cohort is a CDC-sponsored two-year birth cohort in Cincinnati, Ohio conducted during 4/2017 to 8/2020. Mid-turbinate nasal swabs were collected weekly from children and tested using the Luminex Respiratory Pathogen Panel. The primary outcome was prolonged viral infection, which was defined as a viral nucleic acid detection lasting 4 or more weeks. Proportions of prolonged viral infections were compared using Fisher’s exact test with Holms corrections. Adjusted odds ratios (aOR) and 95% confidence intervals were calculated using a mixed effects logistic regression model while controlling for within-subject clustering, viral species, child age, child sex, symptom status, and coinfection. This analysis was limited to subjects who provided at least 70% of weekly samples.

Results

Among 101 children, providing 7871 child-weeks of follow-up, we identified 780 viral infections. The median duration of infection across all respiratory viruses was 1 week, except for bocavirus and coronavirus NL63, each with 2 weeks; 40% of bocavirus and >10% of adenovirus, coronavirus NL63, RSV A, human metapneumovirus, and parainfluenza 1 infections were associated with prolonged infection (>4 weeks). No prolonged infections were detected for influenza A or B, coronavirus 229E or HKU1, or parainfluenza 2 or 4 infections. Viral coinfection (aOR=3.1, 95% CI 1.9, 5.0) and female sex (aOR 1.8, 95%CI 1.1, 2.9) were significantly associated with prolonged infection, while symptom status and child age were not.

Conclusion

In the PREVAIL cohort, detection of respiratory viruses lasting 4 weeks or longer was common for certain respiratory pathogens and was especially prolonged for bocavirus. Biological factors such as the presence of additional viral infections or child sex may affect the likelihood of prolonged infection.

Disclosures

All Authors: No reported disclosures.

880. Molecular Subtyping and Macrolide-Resistance Determination of Mycoplasma pneumoniae from Children Enrolled in New Vaccine Surveillance Network in the United States during 2015 to 2020

Background

Mycoplasma pneumoniae (MP), a common pediatric pneumonia pathogen, has 2 subtypes based on P1 adhesin gene variation. Macrolide-resistant MP (MRMP), seen since 2000 in many countries, has been subtype associated. Limited U.S. pediatric data exist on MP subtype or MRMP frequency and their clinical importance.

Methods

During 2015–2020, mid-turbinate nasal swab (MTNS) specimens and/or throat swabs were collected from children with acute respiratory illness (ARI) enrolled in emergency department (ED) or outpatient and inpatient settings at 4 CDC-funded New Vaccine Surveillance Network sites (Cincinnati, Seattle, Houston, and Kansas City). Specimens were tested for MP and common respiratory viruses by singleplex or multiplex polymerase chain reaction assay (PCR). P1-subtyping for MP positive specimens used multiplex TaqMan real-time PCR while MR was assessed by real time PCR with melt curve analysis (Lightmix®, TIBMolbiol). Select demographic/clinical data were analyzed by P1 subtype (P1–1 vs. P1–2).

Results

Of 208 MTNS specimens from 208 children (median age 5.5 years), 110 (53%) were P1–1, 89 (43%) P1–2, and 9 (4%) untypeable. Of 199 typeable specimens, 111 (56%) came from inpatients while 88 (44%) came from ED/outpatients.Overall MRMP prevalence during 2015–2020 was low (3/208,1.4%); all MRMP (Houston: 1 each in 2016–2017 and 2019–2020, Seattle: 1 in 2018–2019) were P1–1. Differences in P1–2 vs. P1–1 proportions were significant in 2 years: P1–2 dominated in 2015–2016; P1-1 in 2019–2020 (Figure 1). Common clinical symptoms for 199 MP-positive patients were fever (84%, mean 102.5±1.5oF), shortness of breath (82%), wheezing (67%), and cough (60%). Clinical manifestations, hospitalization, and antibiotic use did not differ in P1-1 vs. P1-2 patients. Antibiotics were used in 59/199 (30%) patients overall; amoxicillin was most frequent (48/199, 24%), followed by cefdinir (9/199, 5%) and azithromycin (5/199, 3%).

Conclusion

MP subtypes co-circulated during 2015–2020; P1-2 dominated in 2015–2016, P1-1 in 2018–2019. Signs/symptoms were similar for P1-1 and P1-2. MRMP detection was uncommon among our pediatric subjects. Ongoing surveillance is important to assess potential changes in MR prevalence and temporal subtype variation.

Disclosures

Christopher J Harrison, MD, Astellas: Grant/Research Support|GSK: Grant/Research Support|Merck: Grant/Research Support|Pediatric news: Honoraria|Pfizer: Grant/Research Support Brian R. Lee, PhD, MPH, CDC: Grant/Research Support|Merck: Grant/Research Support Mary E. Moffatt, M.D., Becton and Dickinson and Company: Stocks/Bonds|Biogen: Stocks/Bonds|Coloplast B: Stocks/Bonds|Express Scripts: Stocks/Bonds|Novo Nordisk A/S Spons ADR: Stocks/Bonds|Novo Nordisk A/S-B: Stocks/Bonds|Steris PLC: Stocks/Bonds|Stryker Corp: Stocks/Bonds|Thermo Fisher Scientific: Stocks/Bonds Janet A. Englund, MD, Astra Zeneca: Advisor/Consultant|Astra Zeneca: Grant/Research Support|GlaxoSmithKline: Grant/Research Support|Meissa Vaccine: Advisor/Consultant|Merck: Grant/Research Support|Pfizer: Grant/Research Support|SanofiPasteur: Advisor/Consultant.

237. A Case-Control Study Investigating Household, Community, and Clinical Risk Factors Associated with Multisystem Inflammatory Syndrome in Children (MIS-C) after SARS-CoV-2 Infection

Background

Risk factors for MIS-C, a rare but serious hyperinflammatory syndrome associated with SARS-CoV-2 infection, remain unclear. We evaluated household, clinical, and environmental risk factors potentially associated with MIS-C.

Methods

This investigation included MIS-C cases hospitalized in 14 US pediatric hospitals in 2021. Outpatient controls were frequency-matched to case-patients by age group and site and had a positive SARS-CoV-2 viral test within 3 months of the admission of their matched MIS-C case (Figure 1). We conducted telephone surveys with caregivers and evaluated potential risk factors using mixed effects multivariable logistic regression, including site as a random effect. We queried regarding exposures within the month before hospitalization for MIS-C cases or the month after a positive COVID-19 test for controls. Figure.Patient enrollment timeline.

Enrollment scheme for MIS-C case-patients and SARS-CoV-2-positive outpatient controls. MIS-C case-patients were identified through hospital electronic medical records, while two outpatient controls per case were identified through registries of outpatient SARS-CoV-2 testing logs at facilities affiliated with that medical center. Caregivers of outpatient controls were interviewed at least four weeks after their positive test to ensure they did not develop MIS-C after their infection.

Results

We compared 275 MIS-C case-patients with 494 outpatient SARS-CoV-2-positive controls. Race, ethnicity and social vulnerability indices were similar. MIS-C was more likely among persons who resided in households with &gt;1 resident per room (aOR=1.6, 95% CI: 1.1–2.2), attended a large (≥10 people) event with little to no mask-wearing (aOR=2.2, 95% CI: 1.4–3.5), used public transportation (aOR=1.6, 95% CI: 1.2–2.1), attended school &gt;2 days per week with little to no mask wearing (aOR=2.1, 95% CI: 1.0–4.4), or had a household member test positive for COVID-19 (aOR=2.1, 95% CI: 1.3–3.3). MIS-C was less likely among children with comorbidities (aOR=0.5, 95% CI: 0.3–0.9) and in those who had &gt;1 positive SARS-CoV-2 test at least 1 month apart (aOR=0.4, 95% CI: 0.2–0.6). MIS-C was not associated with a medical history of recurrent infections or family history of underlying rheumatologic disease.

Conclusion

Household crowding, limited masking at large indoor events or schools and use of public transportation were associated with increased likelihood of developing MIS-C after SARS-CoV-2 infection. In contrast, decreased likelihood of MIS-C was associated with having &gt;1 SARS-CoV-2 positive test separated by at least a month. Our data suggest that additional studies are needed to determine if viral load, and/or recurrent infections in the month prior to MIS-C contribute to MIS-C risk. Medical and family history were not associated with MIS-C in our analysis.

Disclosures

Natasha B. Halasa, MD, Quidel: Grant/Research Support|Quidel: equipment donation|Sanofi: Grant/Research Support|Sanofi: HAI testing and vaccine donation Mark Hall, MD, Abbvie: Service on a Data Safety Monitoring Board|Kiadis: Licensing income unrelated to the current submission Mary A. Staat, MD, MPH, Centers for Disease Control and Prevention: Grant/Research Support|Cepheid: Grant/Research Support|National Institute of Health: Grant/Research Support|Uptodate: Royalties Pia S. Pannaraj, MD, MPH, AstraZeneca: Grant/Research Support|Pfizer: Grant/Research Support|Sanofi-Pasteur: Advisor/Consultant|Seqirus: Advisor/Consultant Charlotte V. Hobbs, MD, Biofire (Biomerieux): Advisor/Consultant.

Neighbourhood socio-economic environment predicts adiposity and obesity risk in children under two

BACKGROUND

Neighbourhood socio-economic environment (SEE) is associated with obesity in older children and adults, but little is known about this relationship in younger children. Breastfeeding is an important preventative of adiposity in childhood, but its relationship with neighbourhood SEE is unknown.

AIMS

We assessed differences in adiposity and obesity in children before age two by neighbourhood SEE, controlling for family socio-demographics and breastfeeding duration.

MATERIALS AND METHODS

Family socio-demographics, child body mass index z scores (BMIz), and breastfeeding duration were collected at periodic study visits from participants in PREVAIL (n = 245), a birth cohort in Cincinnati, OH. Addresses were assigned a Deprivation Index score, a validated measure of SEE, and dichotomized into highest SEE (least deprived quartile of scores) and not highest SEE (remaining quartiles). Longitudinal and Poisson models assessed differences in BMIz by SEE over the second year of life and obesity risk at age two, respectively (highest SEE, reference), while attenuation of obesity risk by breastfeeding duration was tested in mediation models.

RESULTS

Residing outside of the highest SEE neighbourhoods was associated with an increased BMIz of 0.04 (95%CI 0.02, 0.06) per month of life and increased obesity risk at age two (aRR: 3.7, 95%CI 1.2, 16.2), controlling for family socio-demographics. Breastfeeding duration attenuated >9% of the obesity risk attributable to SEE (mediated RR: 3.4, 95%CI 1.1, 14.8).

DISCUSSION

In the PREVAIL Cohort, residing outside of the highest SEE neighbourhoods predicted a significant increase in BMIz and obesity risk in children before age two, a relationship that was partially mediated by breastfeeding duration.

CONCLUSION

Breastfeeding support may play an important role in reducing obesity rates in children in lower SEE neighbourhoods.

Factors Associated With COVID-19 Non-vaccination in Adolescents Hospitalized Without COVID-19

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.

Clinical Presentation and Severity of Adenovirus Detection Alone vs Adenovirus Co-detection With Other Respiratory Viruses in US Children With Acute Respiratory Illness from 2016 to 2018

BACKGROUND

Human adenovirus (HAdV) is commonly associated with acute respiratory illnesses (ARI) in children and is also frequently co-detected with other viral pathogens. We compared clinical presentation and outcomes in young children with HAdV detected alone vs co-detected with other respiratory viruses.

METHODS

We used data from a multicenter, prospective, viral surveillance study of children seen in the emergency department and inpatient pediatric settings at seven US sites. Children less than 18 years old with fever and/or respiratory symptoms were enrolled between 12/1/16 and 10/31/18 and tested by molecular methods for HAdV, human rhinovirus/enterovirus (HRV/EV), respiratory syncytial virus (RSV), parainfluenza (PIV, types 1-4), influenza (flu, types A-C), and human metapneumovirus (HMPV). Our primary measure of illness severity was hospitalization; among hospitalized children, secondary severity outcomes included oxygen support and length of stay (LOS).

RESULTS

Of the 18,603 children enrolled, HAdV was detected in 1,136 (6.1%), among whom 646 (56.9%) had co-detection with at least one other respiratory virus. HRV/EV (n = 293, 45.3%) and RSV (n = 123, 19.0%) were the most frequent co-detections. Children with HRV/EV (aOR = 1.61; 95% CI = [1.11-2.34]), RSV (aOR = 4.48; 95% CI = [2.81-7.14]), HMPV (aOR = 3.39; 95% CI = [1.69-6.77]), or ≥ 2 co-detections (aOR = 1.95; 95% CI = [1.14-3.36]) had higher odds of hospitalization compared to children with HAdV alone. Among hospitalized children, HAdV co-detection with RSV or HMPV was each associated with higher odds of oxygen support, while co-detection with PIV or influenza viruses was each associated with higher mean LOS.

CONCLUSIONS

HAdV co-detection with other respiratory viruses was associated with greater disease severity among children with ARI compared to HAdV detection alone.

Measurement of Severe Acute Respiratory Syndrome Coronavirus 2 Antigens in Plasma of Pediatric Patients With Acute Coronavirus Disease 2019 or Multisystem Inflammatory Syndrome in Children Using an Ultrasensitive and Quantitative Immunoassay

BACKGROUND

Detection of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) antigens in blood has high sensitivity in adults with acute coronavirus disease 2019 (COVID-19), but sensitivity in pediatric patients is unclear. Recent data suggest that persistent SARS-CoV-2 spike antigenemia may contribute to multisystem inflammatory syndrome in children (MIS-C). We quantified SARS-CoV-2 nucleocapsid (N) and spike (S) antigens in blood of pediatric patients with either acute COVID-19 or MIS-C using ultrasensitive immunoassays (Meso Scale Discovery).

METHODS

Plasma was collected from inpatients (<21 years) enrolled across 15 hospitals in 15 US states. Acute COVID-19 patients (n = 36) had a range of disease severity and positive nasopharyngeal SARS-CoV-2 RT-PCR within 24 hours of blood collection. Patients with MIS-C (n = 53) met CDC criteria and tested positive for SARS-CoV-2 (RT-PCR or serology). Controls were patients pre-COVID-19 (n = 67) or within 24 hours of negative RT-PCR (n = 43).

RESULTS

Specificities of N and S assays were 95-97% and 100%, respectively. In acute COVID-19 patients, N/S plasma assays had 89%/64% sensitivity; sensitivities in patients with concurrent nasopharyngeal swab cycle threshold (Ct) ≤35 were 93%/63%. Antigen concentrations ranged from 1.28-3844 pg/mL (N) and 1.65-1071 pg/mL (S) and correlated with disease severity. In MIS-C, antigens were detected in 3/53 (5.7%) samples (3 N-positive: 1.7, 1.9, 121.1 pg/mL; 1 S-positive: 2.3 pg/mL); the patient with highest N had positive nasopharyngeal RT-PCR (Ct 22.3) concurrent with blood draw.

CONCLUSIONS

Ultrasensitive blood SARS-CoV-2 antigen measurement has high diagnostic yield in children with acute COVID-19. Antigens were undetectable in most MIS-C patients, suggesting that persistent antigenemia is not a common contributor to MIS-C pathogenesis.

Health Impairments in Children and Adolescents After Hospitalization for Acute COVID-19 or MIS-C

OBJECTIVES

To evaluate risk factors for postdischarge sequelae in children and adolescents hospitalized for acute coronavirus disease 2019 (COVID-19) or multisystem inflammatory syndrome in children (MIS-C).

METHODS

Multicenter prospective cohort study conducted in 25 United States pediatric hospitals. Patients <21-years-old, hospitalized May 2020 to May 2021 for acute COVID-19 or MIS-C with follow-up 2 to 4 months after admission. We assessed readmissions, persistent symptoms or activity impairment, and new morbidities. Multivariable regression was used to calculate adjusted risk ratios (aRR) and 95% confidence intervals (CI).

RESULTS

Of 358 eligible patients, 2 to 4 month survey data were available for 119 of 155 (76.8%) with acute COVID-19 and 160 of 203 (78.8%) with MIS-C. Thirteen (11%) patients with acute COVID-19 and 12 (8%) with MIS-C had a readmission. Thirty-two (26.9%) patients with acute COVID-19 had persistent symptoms (22.7%) or activity impairment (14.3%) and 48 (30.0%) with MIS-C had persistent symptoms (20.0%) or activity impairment (21.3%). For patients with acute COVID-19, persistent symptoms (aRR, 1.29 [95% CI, 1.04-1.59]) and activity impairment (aRR, 1.37 [95% CI, 1.06-1.78]) were associated with more organ systems involved. Patients with MIS-C and pre-existing respiratory conditions more frequently had persistent symptoms (aRR, 3.09 [95% CI, 1.55-6.14]) and those with obesity more frequently had activity impairment (aRR, 2.52 [95% CI, 1.35-4.69]). New morbidities were infrequent (9% COVID-19, 1% MIS-C).

CONCLUSIONS

Over 1 in 4 children hospitalized with acute COVID-19 or MIS-C experienced persistent symptoms or activity impairment for at least 2 months. Patients with MIS-C and respiratory conditions or obesity are at higher risk of prolonged recovery.

Vaccine Effectiveness Against Influenza Hospitalization and Emergency Department Visits in 2 A(H3N2) Dominant Influenza Seasons Among Children <18 Years Old-New Vaccine Surveillance Network 2016-2017 and 2017-2018

Studies have shown egg-adaptive mutations in influenza vaccine strains that might have impaired protection against circulating A(H3N2) influenza viruses during the 2016-2017 and 2017-2018 seasons. We used the test-negative design and multivariable models to assess vaccine effectiveness against influenza-associated hospitalization and emergency department visits among children (<18 years old) during the 2016-2017 and 2017-2018 seasons. Effectiveness was 71% (95% confidence interval, 59%-79%), 46% (35%-55%), and 45% (33%-55%) against A(H1N1)pdm09, A(H3N2), and B viruses respectively, across both seasons. During high-severity seasons with concerns for vaccine mismatch, vaccination offered substantial protection against severe influenza outcomes requiring hospitalization or emergency department visits among children.

Maternal Vaccination and Risk of Hospitalization for Covid-19 among Infants

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.).

A Description of COVID-19-Directed Therapy in Children Admitted to US Intensive Care Units 2020

BACKGROUND

It is unclear how acute coronavirus disease 2019 (COVID-19)-directed therapies are used in children with life-threatening COVID-19 in US hospitals. We described characteristics of children hospitalized in the intensive care unit or step-down unit (ICU/SDU) who received COVID-19-directed therapies and the specific therapies administered.

METHODS

Between March 15, 2020 and December 27, 2020, children <18 years of age in the ICU/SDU with acute COVID-19 at 48 pediatric hospitals in the United States were identified. Demographics, laboratory values, and clinical course were compared in children who did and did not receive COVID-19-directed therapies. Trends in COVID-19-directed therapies over time were evaluated.

RESULTS

Of 424 children in the ICU/SDU, 235 (55%) received COVID-19-directed therapies. Children who received COVID-19-directed therapies were older than those who did not receive COVID-19-directed therapies (13.3 [5.6-16.2] vs 9.8 [0.65-15.9] years), more had underlying medical conditions (188 [80%] vs 104 [55%]; difference = 25% [95% CI: 16% to 34%]), more received respiratory support (206 [88%] vs 71 [38%]; difference = 50% [95% CI: 34% to 56%]), and more died (8 [3.4%] vs 0). Of the 235 children receiving COVID-19-directed therapies, 172 (73%) received systemic steroids and 150 (64%) received remdesivir, with rising remdesivir use over the study period (14% in March/April to 57% November/December).

CONCLUSION

Despite the lack of pediatric data evaluating treatments for COVID-19 in critically ill children, more than half of children requiring intensive or high acuity care received COVID-19-directed therapies.

BNT162b2 Protection against the Omicron Variant in Children and Adolescents

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.).

Influenza clinical testing and oseltamivir treatment in hospitalized children with acute respiratory illness, 2015-2016

BACKGROUND

Antiviral treatment is recommended for all hospitalized children with suspected or confirmed influenza, regardless of their risk profile. Few data exist on adherence to these recommendations, so we sought to determine factors associated with influenza testing and antiviral treatment in children.

METHODS

Hospitalized children <18 years of age with acute respiratory illness (ARI) were enrolled through active surveillance at pediatric medical centers in seven cities between 11/1/2015 and 6/30/2016; clinical information was obtained from parent interview and chart review. We used generalized linear mixed-effects models to identify factors associated with influenza testing and antiviral treatment.

RESULTS

Of the 2299 hospitalized children with ARI enrolled during one influenza season, 51% (n = 1183) were tested clinically for influenza. Clinicians provided antiviral treatment for 61 of 117 (52%) patients with a positive influenza test versus 66 of 1066 (6%) with a negative or unknown test result. In multivariable analyses, factors associated with testing included neuromuscular disease (aOR = 5.35, 95% CI [3.58-8.01]), immunocompromised status (aOR = 2.88, 95% CI [1.66-5.01]), age (aOR = 0.93, 95% CI [0.91-0.96]), private only versus public only insurance (aOR = 0.78, 95% CI [0.63-0.98]), and chronic lung disease (aOR = 0.64, 95% CI [0.51-0.81]). Factors associated with antiviral treatment included neuromuscular disease (aOR = 1.86, 95% CI [1.04, 3.31]), immunocompromised state (aOR = 2.63, 95% CI [1.38, 4.99]), duration of illness (aOR = 0.92, 95% CI [0.84, 0.99]), and chronic lung disease (aOR = 0.60, 95% CI [0.38, 0.95]).

CONCLUSION

Approximately half of children hospitalized with influenza during the 2015-2016 influenza season were treated with antivirals. Because antiviral treatment for influenza is associated with better health outcomes, further studies of subsequent seasons would help evaluate current use of antivirals among children and better understand barriers for treatment.

Frequency, Characteristics and Complications of COVID-19 in Hospitalized Infants

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.

Short- vs Standard-Course Outpatient Antibiotic Therapy for Community-Acquired Pneumonia in Children: The SCOUT-CAP Randomized Clinical Trial

IMPORTANCE

Childhood community-acquired pneumonia (CAP) is usually treated with 10 days of antibiotics. Shorter courses may be effective with fewer adverse effects and decreased potential for antibiotic resistance.

OBJECTIVE

To compare a short (5-day) vs standard (10-day) antibiotic treatment strategy for CAP in young children.

DESIGN, SETTING, AND PARTICIPANTS

Randomized double-blind placebo-controlled clinical trial in outpatient clinic, urgent care, or emergency settings in 8 US cities. A total of 380 healthy children aged 6 to 71 months with nonsevere CAP demonstrating early clinical improvement were enrolled from December 2, 2016, to December 16, 2019. Data were analyzed from January to September 2020.

INTERVENTION

On day 6 of their originally prescribed therapy, participants were randomized 1:1 to receive 5 days of matching placebo or 5 additional days of the same antibiotic.

MAIN OUTCOMES AND MEASURES

The primary end point was the end-of-treatment response adjusted for duration of antibiotic risk (RADAR), a composite end point that ranks each child's clinical response, resolution of symptoms, and antibiotic-associated adverse effects in an ordinal desirability of outcome ranking (DOOR). Within each DOOR rank, participants were further ranked by the number of antibiotic days, assuming that shorter antibiotic durations were more desirable. Using RADAR, the probability of a more desirable outcome was estimated for the short- vs standard-course strategy. In a subset of children, throat swabs were collected between study days 19 and 25 to quantify antibiotic resistance genes in oropharyngeal flora.

RESULTS

A total of 380 children (189 randomized to short course and 191 randomized to standard course) made up the study population. The mean (SD) age was 35.7 (17.2) months, and 194 participants (51%) were male. Of the included children, 8 were Asian, 99 were Black or African American, 234 were White, 32 were multiracial, and 7 were of unknown or unreported race; 33 were Hispanic or Latino, 344 were not Hispanic or Latino, and 3 were of unknown or unreported ethnicity. There were no differences between strategies in the DOOR or its individual components. Fewer than 10% of children in either strategy had an inadequate clinical response. The short-course strategy had a 69% (95% CI, 63-75) probability of a more desirable RADAR outcome compared with the standard-course strategy. A total of 171 children were included in the resistome analysis. The median (range) number of antibiotic resistance genes per prokaryotic cell (RGPC) was significantly lower in the short-course strategy compared with the standard-course strategy for total RGPC (1.17 [0.35-2.43] vs 1.33 [0.46-11.08]; P = .01) and β-lactamase RGPC (0.55 [0.18-1.24] vs 0.60 [0.21-2.45]; P = .03).

CONCLUSIONS AND RELEVANCE

In this study, among children responding to initial treatment for outpatient CAP, a 5-day antibiotic strategy was superior to a 10-day strategy. The shortened approach resulted in similar clinical response and antibiotic-associated adverse effects, while reducing antibiotic exposure and resistance.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier: NCT02891915.

Effectiveness of BNT162b2 Vaccine against Critical Covid-19 in Adolescents

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.).

Effectiveness of Maternal Vaccination with mRNA COVID-19 Vaccine During Pregnancy Against COVID-19-Associated Hospitalization in Infants Aged <6 Months - 17 States, July 2021-January 2022

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.

Measurement of SARS-CoV-2 antigens in plasma of pediatric patients with acute COVID-19 or MIS-C using an ultrasensitive and quantitative immunoassay

BACKGROUND

Detection of SARS-CoV-2 antigens in blood has high sensitivity in adults with acute COVID-19, but sensitivity in pediatric patients is unclear. Recent data suggest that persistent SARS-CoV-2 spike antigenemia may contribute to multisystem inflammatory syndrome in children (MIS-C). We quantified SARS-CoV-2 nucleocapsid (N) and spike (S) antigens in blood of pediatric patients with either acute COVID-19 or MIS-C using ultrasensitive immunoassays (Meso Scale Discovery).

METHODS

Plasma was collected from inpatients (<21 years) enrolled across 15 hospitals in 15 US states. Acute COVID-19 patients (n=36) had a range of disease severity and positive nasopharyngeal SARS-CoV-2 RT-PCR within 24 hours of blood collection. Patients with MIS-C (n=53) met CDC criteria and tested positive for SARS-CoV-2 (RT-PCR or serology). Controls were patients pre-COVID-19 (n=67) or within 24h of negative RT-PCR (n=43).

RESULTS

Specificities of N and S assays were 95-97% and 100%, respectively. In acute COVID-19 patients, N/S plasma assays had 89%/64% sensitivity, respectively; sensitivity in patients with concurrent nasopharyngeal swab cycle threshold (Ct) ≤ 35 were 93%/63%. Antigen concentrations ranged from 1.28-3,844 pg/mL (N) and 1.65-1,071 pg/mL (S) and correlated with disease severity. In MIS-C, antigens were detected in 3/53 (5.7%) samples (3 N-positive: 1.7, 1.9, 121.1 pg/mL; 1 S-positive: 2.3 pg/mL); the patient with highest N had positive nasopharyngeal RT-PCR (Ct 22.3) concurrent with blood draw.

CONCLUSIONS

Ultrasensitive blood SARS-CoV-2 antigen measurement has high diagnostic yield in children with acute COVID-19. Antigens were undetectable in most MIS-C patients, suggesting that persistent antigenemia is not a common contributor to MIS-C pathogenesis.

KEY POINTS

In a U.S. pediatric cohort tested with ultrasensitive immunoassays, SARS-CoV-2 nucleocapsid antigens were detectable in most patients with acute COVID-19, and spike antigens were commonly detectable. Both antigens were undetectable in almost all MIS-C patients.

Enterovirus D68-Associated Acute Respiratory Illness ─ New Vaccine Surveillance Network, United States, July-November 2018-2020

Enterovirus D68 (EV-D68) is associated with a broad spectrum of illnesses, including mild to severe acute respiratory illness (ARI) and acute flaccid myelitis (AFM). Enteroviruses, including EV-D68, are typically detected in the United States during late summer through fall, with year-to-year fluctuations. Before 2014, EV-D68 was infrequently reported to CDC (1). However, numbers of EV-D68 detection have increased in recent years, with a biennial pattern observed during 2014-2018 in the United States, after the expansion of surveillance and wider availability of molecular testing. In 2014, a national outbreak of EV-D68 was detected (2). EV-D68 was also reported in 2016 via local (3) and passive national (4) surveillance. EV-D68 detections were limited in 2017, but substantial circulation was observed in 2018 (5). To assess recent levels of circulation, EV-D68 detections in respiratory specimens collected from patients aged <18 years* with ARI evaluated in emergency departments (EDs) or admitted to one of seven U.S. medical centers^† within the New Vaccine Surveillance Network (NVSN) were summarized. This report provides a provisional description of EV-D68 detections during July-November in 2018, 2019 and 2020, and describes the demographic and clinical characteristics of these patients. In 2018, a total of 382 EV-D68 detections in respiratory specimens obtained from patients aged <18 years with ARI were reported by NVSN; the number decreased to six detections in 2019 and 30 in 2020. Among patients aged <18 years with EV-D68 in 2020, 22 (73%) were non-Hispanic Black (Black) persons. EV-D68 detections in 2020 were lower than anticipated based on the biennial circulation pattern observed since 2014. The circulation of EV-D68 in 2020 might have been limited by widespread COVID-19 mitigation measures; how these changes in behavior might influence the timing and levels of circulation in future years is unknown. Ongoing monitoring of EV-D68 detections is warranted for preparedness for EV-D68-associated ARI and AFM.

Effectiveness of Pfizer-BioNTech mRNA Vaccination Against COVID-19 Hospitalization Among Persons Aged 12-18 Years - United States, June-September 2021

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.

Clinical Influenza Testing Practices in Hospitalized Children at United States Medical Centers, 2015-2018

At nine US hospitals that enrolled children hospitalized with acute respiratory illness (ARI) during 2015-2016 through 2017-2018 influenza seasons, 50% of children with ARI received clinician-initiated testing for influenza and 35% of cases went undiagnosed due to lack of clinician-initiated testing. Marked heterogeneity in testing practice was observed across sites.

Data-driven clustering identifies features distinguishing multisystem inflammatory syndrome from acute COVID-19 in children and adolescents

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.