Study: Omicron much more infectious in US preschoolers than DeltaA new study in JAMA Pediatrics shows the Omicron variant has caused six to eight times the rate of Omicron infections in US preschoolers as the Delta variant, but cases were less severe with Omicron.The study looked at outcomes in US children ages 4 and younger—the last group eligible for vaccination in the country.
Outcomes were emergency room visits, hospitalizations, intensive care unit (ICU) admissions, and mechanical ventilation use within 14 days of COVID-19 diagnosis.Using electronic health records, researchers at Case Western University compared 22,772 children infected with Omicron in late December and late January of this year, to more than 66,000 children infected with the Delta variant between Sep 1 and Nov 15 of 2021, and 10,496 infected with the Delta 2 variant between Nov 16 and Nov 30, 2021.
None of the children had previously documented SARS-CoV-2 infections.Monthly incidence among this cohort was 2.4 to 5.6 cases per 1,000 persons per day in December 2021, and jumped to a peak of 8.6 cases per 1,000 persons per day in the first half of January 2022.
Pediatric patients with Omicron were on average a bit younger—1.5 years of age versus 1.7 years—and had fewer comorbidities.But despite causing less serve illness, pediatric hospitalization were highest in January of this year, because Omicron caused 10 to 15 times the rate of cases than Delta.