BA.2 strain of the coronavirus in children in Hong Kong was more serious for children compared with other variants or compared with parainfluenza or influenza a new study found.

In absolute numbers, however, the research counted a small number of deaths and other serious outcomes, CNN reports.

The findings are considered preliminary because they come from a preprint. And they may be less applicable to the US, where there has been more Covid-19 transmission and thus more population-level immunity.

Need for more treatments for this kids
 

The study offers an important look at the raw power of this variant in a vulnerable population. It also highlights the urgency of Covid-19 vaccination for kids and the need for more treatments for this age group, commented to CNN Dr. Beth Thielen, a pediatric infectious disease specialist at the University of Minnesota in Minneapolis.

Right now, we're fairly limited. We can give remdesivir, but we don't have a lot of other drug treatment tools", she said.
 

Children weren't spared from BA.2. The new study compares the outcomes for children hospitalized with this variant to outcomes for kids hospitalized with previous variants (between January 2020 and November 2021), parainfluenza or the flu. Data on children hospitalized with parainfluenza and influenza came from medical records between January 2015 and December 2018.

Seven times higher odds of dying
 

When the researchers compared fatality rates, they found that children hospitalized with BA.2 had seven times higher odds of dying compared with those hospitalized with the flu, and more than six times higher odds of dying from BA.2 than from parainfluenza.

In February 2022, during the height of Hong Kong's Omicron wave, which was mostly caused by BA.2, 1,147 children were hospitalized, and four died.

The children who died were 11 months, 3 years, 4 years and 9 years old. Three had previously been in good health, and the 9-year-old had muscular dystrophy. None was vaccinated against Covid-19. Two children died from encephalitis, or swelling in their brains.

The case fatality rates were 0.35% for BA.2, 0.05% for influenza and 0.04% for parainfluenza, which causes croup.

In addition, the odds that children would need to be admitted to the pediatric ICU were 18 times higher for BA.2 compared with previous Covid-19 variants, more than twice as high as for the flu and roughly on par with the risks for children hospitalized with parainfluenza.

Three times the odds of having a seizure
 

No cases of febrile seizures were recorded in Hong Kong during previous variants. But children with Omicron's BA.2 subvariant had three times the odds of having a seizure caused by a fever compared with those with flu and more than four times greater odds compared to those with parainfluenza.

Kids with BA.2 also had higher risks of brain swelling than children with parainfluenza but about the same as those with the flu.

In terms of respiratory complications, 5% of hospitalized children infected with BA.2 developed croup, compared with 0.27% of children with other Covid-19-causing variants, making the odds of having group about 11 times higher for BA.2 than for previous variants.

They were about twice as likely to have croup with BA.2 than children hospitalized with the flu.

The study researchers, from the University of Hong Kong, concluded that "The intrinsic severity of Omicron BA.2 is not mild as evident by the fatality and severe complications of the uninfected and unvaccinated children."