New York, Apr 2 (IANS): Children younger than 5 years of age who are infected with the Omicron variant have less risk of severe health outcomes than those infected with the Delta variant, a new study suggests.

The study, published in the journal 'JAMA Pediatrics', also showed that the Omicron variant is 6-8 times more infectious than the Delta variant.

"Omicron is less severe than Delta, however, the reduction of the severity range in clinical outcomes is only 16 to 85 per cent," said researcher Rong Xu from the Case Western Reserve University School of Medicine, Cleveland, Ohio.

"Furthermore, since so many unvaccinated children were infected, the long-term effects of Covid-19 infections on the brain, heart, immune systems and other organs of children remain unknown and worrisome," Xu added.

The severe clinical outcomes ranged from a 16 per cent lower risk for emergency room visits to 85 per cent less risk for mechanical ventilation. And about 1.8 per cent of children infected with Omicron were hospitalised, compared to 3.3 per cent with Delta.

For the study, the team analysed the electronic health records of more than 651,640 children in the US who had a medical encounter with healthcare organixations between 9/2021 and 1/2022, including more than 22,772 children infected with Omicron in late December and late January -- to more than 66,000 children infected when Delta was prevalent in the fall.

The study also compared the records of more than 10,000 children immediately before the detection of Omicron in the US, when Delta was still predominant.

Children younger than 5 are not yet eligible for Covid-19 vaccines and have a low rate of previous SARS-CoV-2 infections, which also limits their pre-existing immunity.

The team examined clinical health outcomes for pediatric patients during a 14-day window following SARS-CoV-2 infection. Among the factors they reviewed were: emergency room visits, hospitalizations, ICU admissions and mechanical ventilation use.

Further demographic data analysis found that children infected with Omicron were on average younger - 1.5 years of age versus 1.7 years - and had fewer comorbidities.