Journal of the Pediatric Infectious Diseases Society

ImportanceMultisystem inflammatory syndrome in children (MIS-C) is an uncommon but severe hyperinflammatory illness occurring 2-6 weeks after SARS-CoV-2 infection. Presentation overlaps with other conditions, and risk factors for severe clinical outcomes differ by patient. Characterizing patterns of MIS-C presentation can guide efforts to reduce misclassification, categorize phenotypes, and identify patients at risk for severe outcomes. ObjectiveTo characterize phenotypic clusters of MIS-C and identify clusters with increased clinical severity. DesignWe describe MIS-C phenotypic clusters inferred using latent class analysis (LCA) applied to the largest cohort to date of cases from U.S. national surveillance. Illness onset ranged from February 2020 through December 2022. SettingNational surveillance comprising data from 55 U.S. public health jurisdictions. ParticipantsWe analyzed 9,333 MIS-C cases. Twenty-nine clinical signs and symptoms were selected for clustering after excluding variables with [≥]20% missingness and [≤]10% or [≥]90% prevalence. We excluded 389 cases missing [≥]10 variables and conducted multiple imputation on the remaining 8,944 (96%) cases. Main Outcomes and MeasuresDifferences by cluster in prevalence of each clinical sign and symptom, percentage of cases admitted to the intensive care unit (ICU), length of hospital and ICU stay, mortality, and relative frequency over time. ResultsLCA identified three clusters characterized by 1) frequent respiratory findings primarily affecting older children (n = 713; 8.0% of cases; median age: 12.7 years); 2) frequent cardiac complications and shock (n = 3,359; 37.6%; 10.8 years); and 3) remaining cases (n = 4,872; 54.5%; 6.8 years). Mean duration of hospitalization and proportion of cases resulting in ICU admission or death were higher in the respiratory (7.9 days; 49.5%; 4.6%; respectively) and shock/cardiac clusters (8.7 days; 82.3%; 1.0%; respectively) compared with other cases (5.3 days; 33.0%; 0.06%; respectively). The proportion of cases in the respiratory and shock/cardiac clusters decreased after emergence of the Omicron variant in the United States. Conclusions and RelevanceMIS-C cases clustered into three subgroups with distinct clinical phenotypes, illness severity, and distribution over time. Use of clusters in future studies may support efforts to evaluate surveillance case definitions and help identify groups at highest risk for severe outcomes. Key pointsO_ST_ABSQuestionC_ST_ABSCan phenotypic clusters of multisystem inflammatory syndrome in children (MIS-C) be identified, and are some clusters associated with increased severity? FindingsWe describe clusters inferred using latent class analysis (LCA) on 9,333 MIS-C cases from U.S. national surveillance 2020-2022. LCA identified three clusters characterized by frequent respiratory symptoms, frequent cardiac complications and shock, and remaining clinically milder cases. Mortality and ICU admission were highest in the respiratory and shock/cardiac clusters; prevalence of these two clusters decreased over time. MeaningMIS-C clusters had distinct presentation, illness severity, and distribution over time, highlighting the importance of recognizing the varied presentation of MIS-C.

Direct comparisons of pediatric hospitalizations for acute COVID-19 and multisystem inflammatory syndrome in children (MIS-C) can inform health system planning. While there were more hospitalizations and deaths from acute COVID-19 amongst Canadian children between March 2020-May 2021, MIS-C cases were more severe, requiring more intensive care and vasopressor support.

As the pandemic enters its fifth month, information regarding COVID-19 in children is rapidly evolving. Here, we explore clinical features and SARS-CoV-2 genetic variation in children presenting with COVID-19. We observed diverse clinical presentations and identified association between disease severity, viral load and age. SARS-CoV-2 genomes from the patients showed limited number of variations and an evolutionary rate comparable to other RNA viruses. We did not identify correlation between disease severity and viral genetic variations. Epidemiological investigation revealed multiple introductions of virus into Southern California.

BackgroundA cohort study was conducted to describe and compare the characteristics of SARS-CoV-2 infection in hospitalized children in three countries. MethodsThis was a retrospective cohort of consecutive children admitted to 15 hospitals (13 in Canada and one each in Iran and Costa Rica) up to November 16, 2020. Cases were included if they had SARS-CoV-2 infection or multi-system inflammatory syndrome in children (MIS-C) with molecular detection of SARS-CoV-2 or positive SARS-CoV-2 serology. ResultsOf 211 included cases (Canada N=95; Costa Rica N=84; Iran N=32), 103 (49%) had a presumptive diagnosis of COVID-19 or MIS-C at admission while 108 (51%) were admitted with other diagnoses. Twenty-one (10%) of 211 met criteria for MIS-C. Eighty-seven (41%) had comorbidities. Children admitted in Canada were older than those admitted to non-Canadian sites (median 4.1 versus 2.2 years; p<0.001) and less likely to require mechanical ventilation (3/95 [3%] versus 15/116 [13%]; p<0.05). Sixty-four of 211 (30%) required supplemental oxygen or intensive care unit (ICU) admission and 4 (1.9%) died. Age < 30 days, admission outside Canada, presence of at least one comorbidity and chest imaging compatible with COVID-19 predicted severe or critical COVID-19 (defined as death or need for supplemental oxygen or ICU admission). ConclusionsApproximately half of hospitalized children with confirmed SARS-CoV-2 infection or MIS-C were admitted with other suspected diagnoses. Disease severity was higher at non-Canadian sites. Neonates, children with comorbidities and those with chest radiographs compatible with COVID-19 were at increased risk for severe or critical COVID-19. Main pointsApproximately half of hospitalized children with laboratory confirmed MIS-C or SARS-CoV-2 infection were admitted with another primary diagnoses. The severity of disease was higher in the middle income countries (Costa Rica and Iran) than in Canada.

ObjectiveWe sought to characterize clinical presentation and healthcare utilization for pediatric COVID-19 in Western Pennsylvania (PA). MethodsWe established and analyzed a registry of pediatric COVID-19 in Western PA that includes cases in patients <22 years of age cared for by the pediatric quaternary medical center in the area and its associated pediatric primary care network from March 11 through August 20, 2020. ResultsOur cohort included 424 pediatric COVID-19 cases (mean age 12.5 years, 47.4% female); 65% reported exposure and 79% presented with symptoms. The most common initial healthcare contact was through telehealth (45%). Most cases were followed as outpatients, but twenty-two patients (4.5%) were hospitalized: 19 with acute COVID-19 disease, and three for multisystem inflammatory syndrome of children (MIS-C). Admitted patients were younger (p<0.001) and more likely to have pre-existing conditions (p<0.001). Black/Hispanic patients were 5.8 times more likely to be hospitalized than white patients (p=0.012). Five patients (1.2%) were admitted to the PICU, including all three MIS-C cases; two required BiPAP and one mechanical ventilation. All patients survived. ConclusionsWe provide a comprehensive snapshot of pediatric COVID-19 disease in an area with low to moderate incidence. In this cohort, COVID-19 was generally a mild disease; however, [~]5% of children were hospitalized. Pediatric patients can be critically ill with this infection, including those presenting with MIS-C.

BackgroundLittle is known regarding the full spectrum of illness among children with SARS-CoV-2 infection across ambulatory and inpatient settings. MethodsActive surveillance was performed for SARS-CoV-2 by polymerase chain reaction among asymptomatic and symptomatic individuals in a quaternary care academic hospital laboratory in Tennessee from March 12-July 17, 2020. For symptomatic patients [&le;]18 years of age, we performed phone follow-up and medical record review to obtain sociodemographic and clinical data on days 2, 7, and 30 after diagnosis and on day 30 for asymptomatic patients [&le;]18 years. Daily and 7-day average test positivity frequencies were calculated for children and adults beginning April 26, 2020. ResultsSARS-CoV-2 was detected in 531/10327 (5.1%) specimens from patients [&le;]18 years, including 46/5752 (0.8%) asymptomatic and 485/4575 (10.6%) specimens from 459 unique symptomatic children. Cough (51%), fever (42%), and headache (41%) were the most common symptoms associated with SARS-CoV-2 infection. SARS-CoV-2-related hospitalization was uncommon (18/459 children; 4%); no children with SARS-CoV-2 infection during the study period required intensive care unit admission. Symptom resolution occurred by follow-up day 2 in 192/459 (42%), by day 7 in 332/459 (72%), and by day 30 in 373/396 (94%). The number of cases and percent positivity rose in late June and July in all ages. ConclusionsIn an integrated healthcare network, most pediatric SARS-CoV-2 infections were mild, brief, and rarely required hospital admission, despite increasing cases as community response measures were relaxed. Key pointsIn an integrated healthcare network in the Southeastern United States, symptomatic SARS-CoV-2 infection in children was generally mild, resolved rapidly, and rarely required hospitalization. Cases increased in children and adults as community mitigation measures became less restrictive.

Generally, children and teenagers do not become seriously ill with COVID-19. However, in countries with high rates of coronavirus disease, children with the syndrome COVID-19 associated inflammation syndrome referred to as PIMS-TS have been reported. Similarities noted between SARS-CoV-2 Spike protein sequences and those of other super antigens has prompted the suggestion that this might be the mechanism by SARS-CoV-ST triggers PIMS-TS. It has also been suggested that the D614G variant found more commonly in the US and across European countries may explain why PIMS-TS appears to be common in these countries. Here we analysed viral sequences from 13 paediatric COVID-19 patients of whom five were diagnosed with PIMS-TS. This is the first characterisation of viruses from PIMS-TS patients. In contrast to what has been hypothesised, we found no evidence of unique sequences associated with the viruses from PIMS-TS patients.

We analyzed the antibody and cytokine responses of twenty-three patients with multisystem inflammatory syndrome of children (MIS-C) that appeared with a three-to-six-week delay following a mild or asymptomatic SARS-CoV-2 infection. These responses were compared to healthy convalescent pediatric COVID-19 patients approximately twenty-eight days after the onset of symptoms. Both groups had strong IgG responses to SARS-CoV-2 spike (S) and nucleocapsid (N) proteins, but the MIS-C patients had weaker antibody responses to certain epitopes in the SARS-CoV-2 S and N proteins and to the S and N proteins of endemic human coronaviruses (HCoV) compared to pediatric convalescent COVID patients. HCoV antibody reactivity was correlated with age. In contrast, MIS-C patients had elevated serum levels of several proinflammatory cytokines compared to convalescent COVID patients, including interleukins IL-6, IL-8, IL-18 and chemokines CCL2, CCL8, CXCL5, CXCL9 and CXCL10 as well as tumor necrosis factor alpha and interferon gamma. Moreover, many cytokine responses of MIS-C patients were positively correlated with antibody responses to the SARS-CoV-2 S, N, membrane and ORF3a proteins while pediatric convalescent COVID patient cytokine responses were more often negatively correlated with antibody responses to the S, N and ORF3a proteins of SARS-CoV-2.

Importance: Respiratory syncytial virus (RSV) hospitalization rates are highest among children <2 years of age. RSV immunization with infant monoclonal antibody or maternal vaccine is recommended to protect all U.S. infants in their first RSV season. For certain high-risk children aged 8-19 months entering their second RSV season, the monoclonal antibody nirsevimab is recommended. Little is known regarding preexisting health conditions as risk factors for RSV-associated respiratory failure in children during their second season. Objectives: To describe children admitted to the pediatric intensive care unit (PICU) for RSV during their second RSV season by preexisting health conditions, and to compare demographic and clinical characteristics across groups. Design, Setting, and Participants: Surveillance registry of children 8- <24 months old admitted to the PICU in 30 pediatric hospitals in the 2023-2024/2024-2025 RSV seasons. All children had an RSV-positive respiratory sample and received respiratory support with high flow nasal cannula, noninvasive ventilation, or invasive mechanical ventilation (IMV). Exposure: Preexisting health conditions potentially increasing risk of severe RSV disease. Main Outcomes and Measures: Patients were classified into four mutually exclusive groups by preexisting health conditions: 1) U.S. nirsevimab eligible criteria, 2) other identified RSV risk conditions (with some evidence of increased risk for severe RSV), 3) other preexisting conditions, and 4) no preexisting conditions. Patient demographic characteristics and level of respiratory support received were compared. Results: Among 574 children: 47 (8.2%) had U.S. nirsevimab eligibility criteria, 76 (13.2%) had other RSV risk conditions, 96 (16.7%) had other preexisting conditions, and 355 (61.8%) had none. A higher proportion of children with nirsevimab eligibility factors (40.4%) than those with other identified RSV risk conditions (17.1%) required IMV, which was higher than other (10.4%) or no (5.9%) preexisting health conditions (ptrend<0.001). Conclusions and Relevance: Approximately 20% of children admitted to the PICU with severe RSV were in the defined groups that met U.S. nirsevimab-eligibility criteria or that had an identified RSV risk condition associated with known risk for severe RSV. A considerable proportion of both groups of children required IMV for respiratory support. These findings may help inform future deliberations regarding U.S. second season nirsevimab-eligibility recommendations.

BackgroundDespite decades of study, the characteristics of infants with invasive group B streptococcus (GBS) late onset disease (LOD) (onset day 7 to 89 of life) and in particular very late onset disease (VLOD) (after day 89 of life) are not well described. Materials and MethodsThis was a retrospective cohort study of infants hospitalized in four Edmonton hospitals April 1, 1994 through June 30, 2022 with LOD or VLOD GBS invasive disease. Data were collected on demographics, date of onset of GBS infection, clinical manifestations and outcomes. ResultsThere were 115 episodes of LOD in 111 infants of which 49 (45%) were preterm. Onset was on median day 27 (IQR 19-40.5) of life. All but one infant was bacteremic while 38 (34%) had proven and 17 (15%) had possible GBS meningitis. Five (5%) died before hospital discharge with all deaths presumed to be due to GBS. There were 11 episodes of VLOD in 11 infants (7 [64%] preterm) presenting on median day 116 (IQR 103-138) (range 93-207) of life. Three (27%) had GBS meningitis. All survived to discharge. Infants with VLOD were less likely to be born vaginally and more likely to be mechanically ventilated during their birth hospitalization and have invasive disease with other pathogens than were infants with LOD. Serotype III accounted for 78% of LOD and 64% of VLOD cases. ConclusionGBS remains a significant cause of infant morbidity and mortality. There is increasing evidence that GBS may sometimes be an opportunistic pathogen in infants over 90 days of age.

ImportanceAntenatal care provides unique opportunities to assess SARS-CoV-2 seroprevalence and antibody response duration after natural infection detected during pregnancy; transplacental antibody transfer may inform peripartum and neonatal protection. ObjectiveEstimate seroprevalence and durability of antibodies from natural infection (anti-nucleocapsid (anti-N) IgG) among pregnant people, and evaluate transplacental transfer efficiency. DesignSeroprevalence study: cross-sectional SARS-CoV-2 antibody screening among pregnant people December 9, 2020-June 19, 2021. Cohort study: Pregnant people screened anti-N IgG+ by Abbott Architect chemiluminescent immunoassay in seroprevalence study or identified through medical records with RT-PCR+ or antigen positive results enrolled in a prospective cohort December 9, 2020-June 30, 2022 to longitudinally measure anti-N IgG responses. We collected cord blood and assessed transplacental transfer of maternally-derived anti-N antibodies. SettingThree hospitals and 14 affiliated clinics providing antenatal and delivery care, Seattle, Washington metropolitan area. ParticipantsSeroprevalence study: pregnant people were screened for SAR-CoV-2 anti-N IgG during routine care. Cohort study: Pregnant people with evidence of prior SARS-CoV-2 infection (screened anti-N IgG+ from seroprevalence study or identified with a RT-PCR+ or antigen positive result from medical records) were enrolled in a cohort study to longitudinally measure anti-N IgG responses. Exposure(s) (for observational studies)COVID-19 diagnosis, symptoms, and disease severity. Main Outcome(s) and Measure(s)Presence and durability of SARS-CoV-2 anti-N IgG, transplacental transfer of maternally-derived anti-N IgG. ResultsOf 1289 pregnant people screened in the seroprevalence study, 5% (65) tested SARS-CoV-2 anti-N IgG+, including 39 (60%) without prior RT-PCR+ or antigen positive results and 53 (82%) without symptoms. Among 89 participants enrolled in the cohort study, 73 (82%) had anti-N IgG+ results during pregnancy. Among 49 participants with delivery samples 33 (67%) were anti-N IgG negative by delivery. Of 24 remaining anti-N IgG+ at delivery with paired cord blood samples, 12 (50%) had efficient transplacental anti-N IgG antibody transfer. Median time from first anti-N IgG to below positive antibody threshold was 17 weeks and did not differ by prior RT-PCR+ or antigen positive status. Conclusions and RelevanceMaternally-derived SARS-CoV-2 antibodies to natural infection may wane before delivery. Vaccines are recommended for pregnant persons to reduce severe illness and confer protection to infants.

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection elicits an antibody response that targets several viral proteins including spike (S) and nucleocapsid (N); S is the major target of neutralizing antibodies. Here, we assess levels of anti-N binding antibodies and anti-S neutralizing antibodies in unvaccinated children compared with unvaccinated older adults following infection. Specifically, we examine neutralization and anti-N binding by sera collected up to 52 weeks following SARS-CoV-2 infection in children and compare these to a cohort of adults, including older adults, most of whom had mild infections that did not require hospitalization. Neutralizing antibody titers were lower in children than adults early after infection, but by 6 months titers were similar between age groups. The neutralizing activity of the childrens sera decreased modestly from one to six months; a pattern that was not significantly different from that observed in adults. However, infection of children induced much lower levels of anti-N antibodies than in adults, and levels of these anti-N antibodies decreased more rapidly in children than in adults, including older adults. These results highlight age-related differences in the antibody responses to SARS-CoV-2 proteins and, as vaccines for children are introduced, may provide comparator data for the longevity of infection-elicited and vaccination-induced neutralizing antibody responses.

The evolving epidemiology of COVID-19, driven by successive SARS-CoV-2 variants of concern (VOCs), has prompted ongoing evaluation of their impact on disease severity in children. In low- and middle-income countries (LMICs), children experience a higher burden of severe respiratory illness and pneumonia-related mortality due to factors such as malnutrition, incomplete immunisation, HIV exposure or infection, tuberculosis, and disparities in access to healthcare services. Hospital-based paediatric studies from LMICs are therefore needed to understand how the epidemiology and severity of COVID-19 have changed across pandemic waves. This study examined 354 hospitalised children with SARS-CoV-2 infection during the ancestral, pre-Omicron (Beta and Delta), and Omicron waves at Tygerberg Hospital in Cape Town, South Africa. We analysed data collected over an extended period, from March 2020 to June 2022. Statistical analyses were used to describe clinical characteristics across variant periods, and multivariable logistic regression models were applied to evaluate associations between potential risk factors and disease severity. Paediatric COVID-19 severity varied across VOC periods, with the highest burden observed during the pre-Omicron (Beta and Delta) waves. In multivariable analyses, younger age and circulating variants were associated with disease severity; CRP levels emerged as a marker associated with more severe illness, and corticosteroid treatment, while also associated with disease severity, reflects clinical response to more severe cases. These findings contribute to a better understanding of the epidemiology and clinical impact of COVID-19 in children and highlight the importance of context-specific surveillance and treatment strategies in resource-limited settings.

BackgroundGiardia lamblia (Giardia) is one of the most common intestinal parasitic infections globally, with an estimated 280 million symptomatic infections annually. In children from low-and middle-income countries (LMICs), Giardia is highly prevalent and has been associated with loss of intestinal barrier function, nutrient-metabolic dysregulation, and linear growth impairment, but specific mechanisms linking Giardia to these outcomes remain poorly understood. Methods and resultsWe used data and samples from a subset of 76 children in a longitudinal birth cohort in Nicaragua to evaluate the natural history and geospatial distribution of Giardia infections, child growth outcomes (weight-for-age [WAZ] and length-for-age [LAZ] z scores), and relationships with established biomarkers of inflammation, intestinal damage, and growth-signaling. During the first 36 months of life, we tested 2,305 stools (1,903 surveillance stools and 402 diarrheal stools) for Giardia by qPCR. The incidence of Giardia-positive stools was 59.6 per 100 child-years. Any detection of Giardia was associated with a reduction in LAZ at 36 months of life ({beta}:-0.16, P=0.042). This effect increased when considering persistent or recurrent Giardia detections ({beta}:-0.26, P=<0.001) as well as living in a high-density Giardia detection area ({beta}:-0.44, P=<0.001). Among intestinal markers, Giardia was only associated with lower median fecal neopterin (a marker of chronic intestinal T cell activation) at 24 and 36 months of age. Among serum systemic biomarkers measured at 24 months, Giardia detections were associated with indicators of intestinal epithelial cell damage (higher median Intestinal Fatty Acid Binding Protein (P=0.002) and Anti-FliC IgA (P=0.033), and reduced growth-signaling hormone (lower median Insulin-like Growth Factor (IGF-1) (P=0.005). ConclusionGiardia detection was negatively associated with linear growth in an exposure-dependent manner. Simultaneously, Giardia associates with diminished serum growth-signaling hormones. Patterns of serum and fecal intestinal biomarkers suggest that Giardia-mediated epithelial disruption is dissociated from markers of intestinal inflammation. Author SummaryAlthough Giardia was recognized as a pathogen by the World Health Organization in 1981, its long-term effects on child health, particularly in endemic areas, remain poorly understood. One major challenge is that most Giardia infections are asymptomatic and go unreported, leading to an underestimation of not only its true burden but also its association with child health outcomes. While a link between Giardia and impaired linear growth is becoming clearer in large prospective child cohorts, considerable variability persists in the strength and consistency of this association across studies. Moreover, the mechanistic pathways underlying long-term sequelae in children remain elusive. To contribute to this field, we leveraged a birth cohort with longitudinal biosampling to study Giardia infections and their impact on child growth. We found that Giardia infection was negatively associated with length-for-age and Insulin-like Growth Factor 1 (IGF-1) levels, positively associated with biomarkers of intestinal epithelial disruption, yet uncoupled from markers of systemic inflammation and intestinal inflammation. The association with poor linear growth, epithelial disruption, and reduced growth signaling from intestinal inflammation which is a unique characteristic of Giardia, requires further investigation of its pathophysiology.

Importance: Understanding population differences in epidemiology, clinical presentation, and genetic architecture remains a major challenge for all rare genetic disorders. Hirschsprung disease (HSCR), despite being the commonest cause of neonatal intestinal obstruction, has been poorly studied with respect to its significant heterogeneity across U.S. populations. Objective: To characterize self-identified race and ethnicity differences in HSCR incidence, clinical presentation, and genetic architecture in the United States from diverse data sources. Design, Setting, and Participants: We used retrospective, population-based surveillance data from 3 independent US wide sources - (1) The National Birth Defects Prevention Network (NBDPN; 1996-2010), (2) aggregated electronic health record data from Epic COSMOS (1997-2025), and (3) individual level clinical and genomic data from the Hirschsprung Disease Research Collaborative (HDRC; 2011-2025). Statistical analyses of incident HSCR cases identified at birth, across time and geography, in conjunction with clinical phenotypes and genome sequences from unrelated HDRC probands were performed to characterize epidemiologic, phenotypic and genetic heterogeneity in HSCR. Exposures: HSCR cases were identified based on standardized clinical diagnostic criteria, primarily rectal biopsy with histopathologic confirmation of aganglionosis. The disease was defined using ICD-9-CM code 751.3, CDC/BPA code 751.30-751.34. and ICD-10-CM code Q43.1. Patients were classified by self-identified race and ethnicity (SIRE), with primary comparisons conducted between non-Hispanic Blacks/African Americans (Blacks) and non-Hispanic Whites (Whites). Main Outcomes and Measures: HSCR incidence and the frequency of clinical features were estimated overall and by SIRE. We also estimated the individual and total genetic burden of rare pathogenic coding variants and common noncoding regulatory variants at established HSCR genes by population. Results: Overall HSCR incidence in the U.S. was 2.04 per 10,000 live births (95% CI, 1.99-2.09) as previously estimated. We show, Blacks have the highest HSCR incidence (2.83-3.13 per 10 000 live births), in comparison to Whites (1.89-2.02) and Asians (1.54-1.98), a difference not previously ascertained from previous smaller cohorts from limited geographical regions. This difference persists across surveillance times and geography. This incidence difference from NBDPN is consistent with Epic COSMOS, a nation-wide, independent hospital-based data source. Clinically, Blacks are more likely to present with isolated HSCR and with milder manifestations at birth, including chronic severe constipation (CSC). Genetically, the burden of pathogenic coding variants did not differ between Blacks and Whites. However, Blacks had a significantly higher enrichment of two non-coding regulatory variants (rs199582499 and rs28735659) at the SOX10 gene locus, as compared with Whites. Conclusions and Relevance: This study demonstrates, for the first time, that Black HSCR patients in the U.S. have a higher incidence accompanied by milder clinical presentation and distinct noncoding regulatory SOX10 variants as compared to White patients. Nevertheless, Blacks are severely under-represented in U.S. studies of HSCR leading to significant health disparities in their care and management.

The impact of post-acute sequelae of SARS-CoV-2 infection (PASC) in children is underrecognized. We developed an EHR-based algorithm across eight pediatric institutions to identify children with COVID-19 based on serology testing from 3/2020 through 4/2022 who had not been identified by PCR. Overall, serology tests were used 100-fold less than PCR. Seroprevalence of IgG anti-nucleocapsid antibodies remained stable, while rates of positive IgG anti-spike antibodies increased in teenagers after COVID-19 vaccine approval. Through data harmonization and after excluding 1,410 serology test results that may have been influenced by vaccines, we identified 2,714 children that were COVID-19 positive exclusively by serology. These patients were frequently tested as inpatients (24% vs. 2%), had chronic conditions more frequently (37% vs 24%), and a MIS-C diagnosis (23% vs. <1%) compared with PCR-positive children. Identification of children that could have been paucisymptomatic, not tested, or missed is critical to define the burden of PASC in children.

ImportanceThe effects of SARS-CoV-2 infection on immune responses during pregnancy have not been systematically evaluated. ObjectiveTo assess the impact of SARS-CoV-2 infection during pregnancy on inflammatory and humoral responses in maternal and fetal samples and compare antibody responses to SARS-CoV-2 among pregnant and non-pregnant women. DesignImmune responses to SARS-CoV-2 were analyzed using samples from pregnant and non-pregnant women who had either tested positive or negative for SARS-CoV-2. We measured, proinflammatory and placental cytokine mRNAs, neonatal Fc receptor (FcRn) receptor expression, and tetanus antibody transfer in maternal and cord blood samples. Additionally, we measured anti-spike (S) IgG, anti-S-receptor binding domain (RBD) IgG, and neutralizing antibody (nAb) responses to SARS-CoV-2 in serum or plasma collected from non-pregnant women, pregnant women, and cord blood. SettingJohns Hopkins Hospital (JHH) ParticipantsPregnant women were recruited through JHH outpatient obstetric clinics and the JHH Labor & Delivery unit. Non-pregnant women were recruited after receiving outpatient SARS-CoV-2 testing within Johns Hopkins Health System, USA. Adult non-pregnant women with positive RT-PCR results for SARS-CoV-2, within the age range of 18-48 years, were included in the study. ExposuresSARS-CoV-2 Main Outcomes and MeasuresParticipant demographic characteristics, antibody titers, cytokine mRNA expression, and FcRn receptor expression. ResultsSARS-COV-2 positive pregnant women expressed more IL1{beta}, but not IL6, in blood samples collected within 14 days versus > 14 days after a confirmed SARS-CoV-2 test, with similar patterns observed in the fetal side of placentas, particularly among asymptomatic pregnant women. Pregnant women with confirmed SARS-CoV-2 infection also had reduced anti-S-RBD IgG titers and were less likely to have detectable nAb as compared with non-pregnant women. Although SARS-CoV-2 infection did not disrupt FcRn expression in the placenta, maternal transfer of nAb was inhibited by SARS-CoV-2 infection during pregnancy. Conclusions and RelevanceSARS-CoV-2 infection during pregnancy was characterized by placental inflammation and reduced antiviral antibody responses, which may impact the efficacy of COVID-19 therapeutics in pregnancy. The long-term implications of placental inflammation for neonatal health also requires greater consideration.

Enteric pathogen infections are a major global health challenge, influenced by a variety of host and environmental factors, and their clinical presentation and treatment can be complicated by the presence of co-infections. The prevalence of enteric infections and co-infections tend to vary between rural and urban contexts, likely driven by underlying environmental, geographic, and demographic characteristics. To improve understanding of urbanicity and age on enteric pathogen prevalence and on co-infection risk, we measured 22 enteric pathogens in fecal samples collected from children aged 6, 12, and 18 months across a rural-urban gradient within the ECoMiD birth cohort study (n=473). Enteric pathogen burden was high and increased with age, with at least one pathogen detected in 91% of children at 6 months, 97% at 12 months, and 98% at 18 months. However, prevalence of some pathogens-- notably Salmonella enterica, enterovirus, and rotavirus-- decreased with age. Co-infections were also common (88%), and children were infected with as many as 11 pathogens simultaneously. The most frequently observed co-infection profiles included enteroaggregative E. coli and atypical enteropathogenic E. coli, followed by combinations with diffusely adherent E. coli, enterovirus, enterotoxigenic E. coli, and/or adenovirus. Enteric pathogen detection generally was higher in more rural settings, though patterns varied by pathogen. These results provide useful information for future examination of pathogen dynamics of co-occurrence. Given the ubiquity of enteric infections in high transmission settings, strategies that aim to reduce overall microbial exposure may be needed to supplement interventions targeting control of individual pathogens.

Respiratory syncytial virus (RSV) infections and hospitalizations surged sharply in 2022 among young children. To assess whether COVID-19 contributed to this surge, we leveraged a real-time nation-wide US database of electronic health records (EHRs) using time series analysis from January 1, 2010 through January 31, 2023, and propensity-score matched cohort comparisons for children aged 0-5 years with or without prior COVID-19 infection. Seasonal patterns of medically attended RSV infections were significantly disrupted during the COVID-19 pandemic. The monthly incidence rate for first-time medically attended cases, most of which were severe RSV-associated diseases, reached a historical high rate of 2,182 cases per 1,0000,000 person-days in November 2022, corresponding to a related increase of 143% compared to expected peak rate (rate ratio: 2.43, 95% CI: 2.25-2.63). Among 228,940 children aged 0-5 years, the risk for first-time medically attended RSV during 10/2022-12/2022 was 6.40% for children with prior COVID-19 infection, higher than 4.30% for the matched children without COVID-19 (risk ratio or RR: 1.40, 95% CI: 1.27-1.55); and among 99,105 children aged 0-1 year, the overall risk was 7.90% for those with prior COVID-19 infection, higher than 5.64% for matched children without (RR: 1.40, 95% CI: 1.21-1.62). These data provide evidence that COVID-19 contributed to the 2022 surge of severe pediatric RSV cases.

The evolution of SARS-CoV2 virus has led to the emergence of variants of concern (VOC). Children, particularly <12 years old not yet eligible for vaccines, continue to be important reservoirs of SARS-CoV-2 yet VOC prevalence data in this population is lacking. We report data from a genomic surveillance program that includes 9 U.S. childrens hospitals. Analysis of SARS-CoV-2 genomes from 2119 patients <19 years old between 03/20 to 04/21 identified 252 VOCs and 560 VOC signature mutations, most from 10/20 onwards. From 02/21 to 04/21, B.1.1.7 prevalence increased from 3.85% to 72.22% corresponding with the decline of B.1.429/B.1.427 from 51.82% to 16.67% at one institution. 71.74% of the VOC signature mutations detected were in children <12 years old, including 33 cases of B.1.1.7 and 119 of B.1.429/B.1.427. There continues to be a need for ongoing genomic surveillance, particularly among young children who will be the last groups to be vaccinated.