Wang et al.: COVID infection severity in children < 5 years old before & after Omicron emergence in the US, compared severity of clinic outcomes in children under 5 who contracted COVID infection

First time SARS-CoV-2 infections occurring when Omicron dominant (prev >92%) was associated with significantly less severe outcomes than first-time infections in similar children when delta dominant

Very good news as it shows the low risk in children to begin but really that Omicron is even much milder for children.

7,201 infected between 12/26/2021-1/6/2022 when the Omicron predominated (Omicron cohort), 63,203 infected between 9/1/2021-11/15/2021 when the Delta predominated (Delta cohort)

Vert good study; retrospective, propensity-score matching, severity of COVID infections including emergency department (ED) visits, hospitalizations, intensive care unit (ICU) admissions, and mechanical ventilation use in the 3-day time-window following SARS-CoV-2 infection were compared between Omicron and Delta cohorts, and between Delta-2 and Delta cohorts.

“After propensity-score matching for demographics, socio-economic determinants of health, comorbidities and medications, risks for severe clinical outcomes in the Omicron cohort were significantly lower than those in the Delta cohort: ED visits: 18.83% vs. 26.67% (risk ratio or RR: 0.71 [0.66-0.75]); hospitalizations: 1.04% vs. 3.14% (RR: 0.33 [0.26-0.43]); ICU admissions: 0.14% vs. 0.43% (RR: 0.32 [0.16-0.66]); mechanical ventilation: 0.33% vs. 1.15% (RR: 0.29 [0.18-0.46]). Control studies comparing Delta-2 to Delta cohorts show no difference.”

There is a 29% reduction in ED visits, 67% reduction in hospitalizations, 68% reduction in ICU admissions, and 71% reduction in mechanical ventilation; from the Omicron cohort relative to those from the matched Delta cohort.

Researchers concluded that for children < 5 years of age, ‘first time SARS-CoV-2 infections occurring when the Omicron predominated (prevalence >92%) was associated with significantly less severe outcomes than first-time infections in similar children when the Delta variant predominated.’

ref: https://www.medrxiv.org/content/10.1101/2022.01.12.22269179v1.full.pdf