Trends in Disease Severity among Critically Ill Children with Severe Acute Respiratory Syndrome Coronavirus 2: A Retrospective Multicenter Cohort Study in the United States∗

OBJECTIVES: To describe trends in critical illness from severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection in children over the course of the COVID-19 pandemic. We hypothesized that PICU admission rates were higher in the Omicron period compared with the original outbreak but that fewer patients needed endotracheal intubation. DESIGN: Retrospective cohort study. SETTING: This study took place in nine U.S. PICUs over 3 weeks in January 2022 (Omicron period) compared with 3 weeks in March 2020 (original period). PATIENTS: Patients less than or equal to 21 years old who screened positive for SARS-CoV-2 infection by polymerase chain reaction or hospital-based rapid antigen test and were admitted to a PICU or intermediate care unit were included. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: A total of 267 patients (239 Omicron and 28 original) were reviewed. Forty-five patients in the Omicron cohort had incidental SARS-CoV-2 and were excluded from analysis. The Omicron cohort patients were younger compared with the original cohort patients (median [interquartile range], 6 yr [1.3-13.3 yr] vs 14 yr [8.3-17.3 yr]; p = 0.001). The Omicron period, compared with the original period, was associated with an average increase in COVID-19-related PICU admissions of 13 patients per institution (95% CI, 6-36; p = 0.008), which represents a seven-fold increase in the absolute number admissions. We failed to identify an association between cohort period (Omicron vs original) and odds of intubation (odds ratio, 0.7; 95% CI, 0.3-1.7). However, we cannot exclude the possibility of up to 70% reduction in intubation. CONCLUSIONS: COVID-19-related PICU admissions were seven times higher in the Omicron wave compared with the original outbreak. We could not exclude the possibility of up to 70% reduction in use of intubation in the Omicron versus original epoch, which may represent differences in PICU/hospital admission policy in the later period, or pattern of disease, or possibly the impact of vaccination.