Hematologic manifestations of SARS-CoV-2 infection and MIS-C in hospitalized children. Results of the PICNIC registry. (preprint)

Introduction: Hematologic complications of SARS-CoV-2 infection are well described in hospitalized adults with correlation to adverse outcomes. Information published in children has been limited. Methods: An international multi-centered retrospective registry was established to collect data on the clinical manifestations of SARS-CoV-2 or multisystem inflammatory syndrome (MIS-C) in hospitalized children between February 1, 2020 – May 31, 2021. This sub-study focused on hematologic manifestations. Study variables included patient demographics, comorbidities, clinical presentation, course, laboratory parameters, management, and outcomes. Results: Nine hundred and eighty-five children were enrolled and 915 (93%) had clinical information available; 385 (42%) had symptomatic SARS-CoV-2 infection upon admission, 288 had MIS-C (31.4%) and 242 (26.4%) had alternate diagnosis with SARS-CoV-2 identified incidentally. During hospitalization, 10 children (1%) experienced a thrombotic event, 16 (1.7%) had hemorrhage and 2 (0.2%) had both thrombotic and hemorrhagic episodes. Significant prothrombotic comorbidities included congenital heart disease (p-value = 0.007), central venous catheter (p = 0.04) in children with primary SARS-CoV-2 infection; and obesity (p-value= 0.002), cytokine storm (p= 0.012) in those with MIS-C. Significant pro- hemorrhagic conditions included age > 10 years (p = 0.04), CVC (p= 0.03) in children with primary SARS-CoV-2infection; and thrombocytopenia (0.001), cytokine storm (0.02) in those with MIS-C. Eleven patients died (1.2 %) with no deaths attributed to thrombosis or hemorrhage Conclusion: Thrombotic and hemorrhagic complications are uncommon in children with SARS-CoV-2 infection and observed with underlying co-morbid conditions. Understanding the complete spectrum of hematologic complications in children with SARS-CoV-2 infection or MIS-C requires ongoing multi-center studies.

Infants Hospitalized for Acute COVID-19: Disease Severity in a Multicenter Cohort Study (preprint)

Age is the most important determinant of COVID-19 severity. Infectious disease severity by age is typically J-shaped, with infants and the elderly carrying a high burden of disease. We report on the comparative disease severity between infants and older children in a multicenter retrospective cohort study of children 0 to 17 year old admitted for acute COVID-19 February 2020 through May 2021 in 17 pediatric hospitals. We compare clinical and laboratory characteristics and estimate the association between age group and disease severity using ordinal logistic regression. We found that infants comprised one third of cases, but were admitted for a shorter period (median 3 days IQR 2-5 versus 4 days IQR 2-7), had a lower likelihood to have an increased C-reactive protein and had half the odds of older children of having severe or critical disease (OR 0.50 (95% Confidence Interval 0.32-0.78)). Conclusion: When compared to older children, there appeared to be a lower threshold to admit infants but their length of stay is shorter and they have a lower odds than older children of progressing to severe or critical disease.

Risk factors for severe PCR-positive SARS-CoV-2 infection in hospitalized children: a multicenter cohort study (preprint)

Importance: Children are less likely than adults to have severe outcomes from SARS-CoV-2 infection and the corresponding risk factors are not well established. Objective: To identify risk factors for severe disease in symptomatic children hospitalized for PCR-positive SARS-CoV-2 infection. Design: Cohort study, enrollment from February 1, 2020 until May 31, 2021 Setting 15 children's hospitals in Canada, Iran, and Costa Rica Participants: Patients <18 years of age hospitalized with symptomatic SARS-CoV-2 infection, including PCR-positive multisystem inflammatory syndrome in children (MIS-C) Exposures: Variables assessed for their association with disease severity included patient demographics, presence of comorbidities, clinical manifestations, laboratory parameters and chest imaging findings. Main Outcomes and Measures: The primary outcome was severe disease defined as a WHO COVID-19 clinical progression scale of [≥]6, i.e., requirement of non-invasive ventilation, high flow nasal cannula, mechanical ventilation, vasopressors, or death. Multivariable logistic regression was used to evaluate factors associated with severe disease. Results: We identified 403 hospitalizations. Median age was 3.78 years (IQR 0.53-10.77). At least one comorbidity was present in 46.4% (187/403) and multiple comorbidities in 18.6% (75/403). Severe disease occurred in 33.8% (102/403). In multivariable analyses, presence of multiple comorbidities (adjusted odds ratio 2.24, 95% confidence interval 1.04-4.81), obesity (2.87, 1.19-6.93), neurological disorder (3.22, 1.37-7.56), anemia, and/or hemoglobinopathy (5.88, 1.30-26.46), shortness of breath (4.37, 2.08-9.16), bacterial and/or viral coinfections (2.26, 1.08-4.73), chest imaging compatible with COVID-19 (2.99, 1.51-5.92), neutrophilia (2.60, 1.35-5.02), and MIS-C diagnosis (3.86, 1.56-9.51) were independent risk factors for severity. Comorbidities, especially obesity (40.9% vs 3.9%, p<0.001), were more frequently present in adolescents [≥]12 years of age. Neurological disorder (3.16, 1.19-8.43) in children <12 years of age and obesity (3.21, 1.15-8.93) in adolescents were the specific comorbidities associated with disease severity in age-stratified adjusted analyses. Sensitivity analyses excluding the 81 cases with MIS-C did not substantially change the identified risk factors. Conclusions and Relevance: Pediatric risk factors for severe SARS-CoV-2 infection vary according to age and can potentially guide vaccination programs and treatment approaches in children.

Multicenter cohort study of multisystem inflammatory syndrome in children (MIS-C) (preprint)

BACKGROUND SARS-CoV-2 infection can lead to multisystem inflammatory syndrome in children (MIS-C). We investigated risk factors for severe disease and explored changes in severity over time. METHODS Children up to 17 years of age admitted March 1, 2020 through March 7 th , 2021 to 15 hospitals in Canada, Iran and Costa Rica with confirmed or probable MIS-C were included. Descriptive analysis and comparison by diagnostic criteria, country, and admission date was performed. Adjusted absolute average risks (AR) and risk differences (RD) were estimated for characteristics associated with ICU admission or cardiac involvement. RESULTS Of 232 cases (106 confirmed) with median age 5.8 years, 56% were male, and 22% had comorbidities. ICU admission occurred in 73 (31%) but none died. Median length of stay was 6 days (inter-quartile range 4-9). Children 6 to 12 years old had the highest AR for ICU admission (44%; 95% confidence interval [CI] 34-53). Initial ferritin greater than 500 mcg/L was associated with ICU admission. When comparing cases admitted up to October 31, 2020 to those admitted later, the AR for ICU admission increased from 25% (CI 17-33) to 37% (CI 29-46) and for cardiac involvement from 44% (CI 35-53) to 75% (CI 66-84). Risk estimates for ICU admission in the Canadian cohort demonstrated a higher risk in December 2020-March 2021 compared to March-May 2020 (RD 25%; 95%CI 7-44). INTERPRETATION MIS-C occurred primarily in previously well children. Illness severity appeared to increase over time. Despite a high ICU admission incidence, most children were discharged within one week.

Multicenter cohort study of children hospitalized with SARS-CoV-2 infection (preprint)

Background: A cohort study was conducted to describe and compare the burden and characteristics of SARS-CoV-2 infection in hospitalized children in three countries. Methods: This 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. Results: Of 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). Requirement for oxygen or ICU occurred in 64 (30%) and death in four, three of whom. had malignancies. Age < 30 days, admission outside of Canada, presence of at least one comorbidity and chest imaging compatible with COVID-19 predicted severe disease. Conclusions: Approximately half of hospitalized children with confirmed SARS-CoV-2 infection or MIS-C were admitted with other suspected diagnoses. Disease was more severe at non-Canadian sites. Neonates, children with comorbidities and those with chest radiographs compatible with COVID-19 were at increased risk for severe disease.