Background Recent COVID-19 surges are attributed to emergence of more transmissible SARS-CoV-2 variants of concern (VOCs). The relative severity of VOCs in children is unknown. Methods We performed a single-center retrospective cohort study of children ≤18 years old diagnosed with COVID-19 from October 2020–February 2022 and whose SARS-CoV-2 isolate underwent Illumina sequencing. We measured the frequency of five markers of COVID-19 severity. Logistic regression models were fitted to estimate the odds of each severity marker with each VOC. Results Among 714 children, 471 (66.0%) were infected with a VOC: 96 (13.4%) alpha, 38 (5.3%) gamma, 119 (16.7%) delta, and 215 (30.1%) omicron. High-risk medical conditions and increasing age were independently associated with COVID-19 severity. After adjusting for age, race, ethnicity, high-risk medical conditions, and COVID-19 community incidence, neither alpha, delta, nor omicron was associated with severe COVID-19. Gamma was independently associated with hospitalization (OR 6.7, 95% CI 2.0–22.1); pharmacologic treatment (OR 5.7, 95% CI 1.2–26.8); respiratory support (OR 11.9, 95% CI 2.7–62.4); and severe disease per the WHO Clinical Progression Scale (OR 11.7, 95% CI 2.1–90.5). Upon subgroup analyses, omicron was independently associated with ICU admission and severe disease per the WHO Clinical Progression Scale in children without SARS-CoV-2 immunization or prior COVID-19 infection. Conclusions Compared to non-VOC COVID-19, the gamma VOC was independently associated with increased COVID-19 severity, as was omicron in children without SARS-CoV-2 immunization or prior COVID-19 infection. SARS-CoV-2 vaccination and prior COVID-19 prevented severe outcomes during the omicron surge.

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Objectives To assess rates of asymptomatic SARS-CoV-2 positivity in K-8 schools with risk mititgation procedures in place, and to evaluate SARS-CoV-2 transmission in school and household contacts of these positive individuals. Study design In this prospective observational study, screening testing for SARS-CoV-2 was performed by oropharyngeal swabbing and PCR in students and staff at K-8 private schools in high-risk Chicago zip codes. New COVID-19 diagnoses or symptoms among participants, household contacts, and non-participants in each school were queried. Results Among 11 K-8 private schools across 8 Chicago zip codes, 468 participants (346 students, 122 staff members) underwent screening testing. At the first school, 17 participants (36%) tested positive, but epidemiologic investigation suggested against in-school transmission. Only 5 participants in the subsequent 10 schools tested positive for an overall 4.7% positivity rate (1.2% excluding School 1). All but one positive test among in-person students had high PCR cycle threshold values, suggesting very low SARS-CoV-2 viral loads. In all schools, no additional students, staff, or household contacts reported new diagnoses or symptoms of COVID-19 during the two weeks following screening testing. Conclusions We identified infrequent asymptomatic COVID-19 in schools in high-risk Chicago communities and did not identify transmission among school staff, students, or their household contacts. These data suggest that COVID-19 mitigation procedures, including masking and physical distancing, are effective in preventing transmission of COVID-19 in schools. These results may inform future strategies for screening testing in K-8 schools.

Background: Recent surges in coronavirus 2019 disease (COVID-19) is attributed to the emergence of more transmissible severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) variants of concern (VOCs). However, the relative severity of SARS-CoV-2 VOCs in children is unknown. Methods: This retrospective single-center cohort study was performed at the Ann & Robert H. Lurie Childrens Hospital of Chicago, academic free-standing childrens hospital. We included all children 0-18 years-old diagnosed with COVID-19 between October 15th, 2020 and August 31st, 2021 and whose SARS-CoV-2 isolate was sequenced using the Illumina platform. For each patient sample, we identified the SARS-CoV-2 lineage, which was assigned to one of the following groups: Non-VOC, alpha VOC, beta VOC, gamma VOC, or delta VOC. We measured frequency of 5 markers of COVID-19 severity: hospitalization; COVID-19 pharmacologic treatment; respiratory support; intensive care unit admission; and severe disease as classified by the COVID-19 World Health Organization (WHO) Clinical Progression Scale (severe disease; score of 6 or higher). A series of logistic regression models were fitted to estimate odds of each severity marker with each VOC (in comparison to non-VOCs), adjusting for COVID-19 community incidence and demographic and clinical co-variates. Results: During the study period, 2,025 patients tested positive for SARS-CoV-2; 1,422 (70.2%) had sufficient viral load to permit sequencing. Among the 499 (35.1%) patients whose isolate was sequenced, median (inter-quartile range) age was 7 (1,12) years; 256 (51.3%) isolates were a VOC: 96 (37.5%) alpha, 38 (14.8%) gamma, and 119 (46.5%) delta. After adjusting for age, Black race, Hispanic ethnicity, high-risk medical conditions, and COVID-19 community incidence, neither alpha nor delta was associated with severe COVID-19. Gamma was independently associated with hospitalization (OR 5.9, 95% CI 1.6-21.5, p=0.007), respiratory support (OR 8.3, 95% CI 1.5-56.3, p=0.02), and severe disease as classified by the WHO Clinical Progression Scale (OR 7.7, 95% CI 1.0-78.1, p=0.05). Conclusions: Compared to non-VOC COVID-19 infections, the gamma VOC, but not the alpha or delta VOCs, was associated with increased severity. These data suggest that recent increased in pediatric COVID-19 hospitalizations are related to increased delta COVID-19 incidence rather than increased delta virulence in children.

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