Study: Omicron ‘Less Severe’ for Kids Under 5 Than Delta


Apr. 2, 2022 — Children younger than 5 infected with the Omicron variant of COVID-19 had “less severe health outcomes” than children in the same age group infected with Delta, according to a study published in JAMA Pediatrics.

Case Western Reserve University (CWRU) School of Medicine researchers looked at electronic health records of children 4 and younger, the age group not eligible to be vaccinated in the United States.

While researchers found Omicron was 6-8 times more infectious than Delta for the age group, the kids generally didn’t get as sick with Omicron.

Omicron cases had a 16% lower risk for emergency room visits and an 85% lower risk for mechanical ventilation, a news release from Case Western said. About 1.8% of Omicron cases in the age group resulted in hospitalization, compared to 3.3% for Delta.

“The major conclusion to our research was that many more children were infected with Omicron when compared to Delta, but the children who are infected are not impacted as severely as were children infected with the Delta variant,” Pamela Davis, a professor at Case Western Reserve School of Medicine, said in the news release.

“However, because there are so many more children infected, our hospitals were affected over the winter months by an influx of young children.”

The research team examined electronic health records of more than 651,600 children from September 2021 to January 2022. Included were almost 23,000 children infected with Omicron in late December 2021 and late January 2022 and more than 66,000 children infected in the fall of 2021, when Delta was prevalent. Also analyzed were records of 10,000 children immediately before the detection of Omicron in the U.S. but when Delta still dominated.

The team looked at whether the children had “clinical health outcomes” – such as emergency room visits, hospitalizations, ICU admissions, and mechanical ventilation use —

during a 14-day period after discovery of COVID infection.

Another finding: Children infected with Omicron tended to be a little younger – on average 1.5 years old, compared to 1.7 years old for Delta – and had fewer comorbidities, the study found.

“We saw the number of hospitalizations within this age group skyrocket in January of this year because the infection rate of Omicron is about 10 to 15 times compared to that of the Delta variant,” Rong Xu, professor of biomedical informatics and director of the Center for AI in Drug Discovery at the medical school, said in the news release.

“Omicron is less severe than Delta, however, the reduction of the severity range in clinical outcomes is only 16 to 85%. Furthermore, since so many un-vaccinated children were infected, the long-term effects of COVID-19 infections on the brain, heart, immune systems and other organs of children remains unknown and worrisome.”