(CNN) — A new study in Hong Kong on the severity of the BA.2 subvariant of the coronavirus in children found that it was more severe for children compared to other variants or compared to parainfluenza or influenza. However, in absolute numbers, the research counted a small number of deaths and other serious outcomes, and the findings may be less applicable to the United States, where there has been more transmission of Covid-19 and thus more immunity at the global level. of population.
The findings are considered preliminary because they come from a preprint or study that has not been reviewed by outside researchers or published in a medical journal. They have also not been confirmed by other studies, which makes them less safe.
“I think it’s a little hard to know what that’s going to be like here, where probably a large fraction of our population has been exposed at some point before to (the subvariant) delta or BA.1,” said Dr. Beth Thielen, a pediatrician specializing in infectious diseases from the University of Minnesota in Minneapolis.
But Thielen notes that the study offers an important look at the raw power of this variant in a vulnerable population. She also highlights the urgency of vaccination against covid-19 for children and the need for more treatments for this age group.
“Right now, we’re pretty limited,” Thielen said. “We can give them remdesivir, but we don’t have a lot of other drug treatment tools.”
The BA.2 variant hits children, a vulnerable population
Throughout the pandemic, Hong Kong has implemented strict control measures against COVID-19, including universal use of face masks, strict social distancing, contact tracing, and the closure of businesses and schools. As a result, this city had low levels of cases and relatively little exposure to the SARS-CoV-2 virus during most of the pandemic.
At least that was true until the highly contagious BA.2 subvariant of the omicron strain came to town. Since then, Hong Kong has seen an alarming rise in cases and deaths, particularly among the elderly population, many of whom had been reluctant to get vaccinated.
But children weren’t spared from BA.2 either, and the new study compares the outcomes of children hospitalized with this variant with the outcomes of children hospitalized with earlier variants (between January 2020 and November 2021), parainfluenza, or the flu. Data on children hospitalized with parainfluenza and influenza come from medical records between January 2015 and December 2018.
In February 2022, during the height of the omicron wave in Hong Kong, caused mainly by BA.2, 1,147 children were hospitalized and four died.
The children who died were 11 months old, 3 years old, 4 years old and 9 years old. Three had previously been in good health, and the 9-year-old boy had muscular dystrophy. None were vaccinated against covid-19. Two children died of encephalitis, or swelling in the brain.
These were the first children to die of covid-19 in Hong Kong during the pandemic.
When the researchers compared mortality rates, they found that children hospitalized with BA.2 were seven times more likely to die compared to those hospitalized with the flu, and more than six times more likely to die from BA.2 than from parainfluenza.
Case fatality rates were 0.35% for BA.2, 0.05% for influenza, and 0.04% for parainfluenza, which causes croup or acute laryngotracheobronchitis.
In addition, the odds of children needing to be admitted to the pediatric ICU were 18 times higher for BA.2 compared to 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.
No cases of febrile seizures were reported in Hong Kong during the above variants. But children who were infected with the omicron subvariant BA.2 were three times more likely to have a seizure caused by fever compared to those with the flu and more than four times more likely compared to those with parainfluenza.
Children with BA.2 also had higher risks of brain inflammation 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 to 0.27% of children with other causative variants of covid-19, making the odds of having a group with BA.2 are 11 times greater than for previous variants.
They were twice as likely to have croup with BA.2 as children hospitalized with the flu.
The study’s researchers, from the University of Hong Kong, concluded that “the intrinsic severity of omicron (subvariant) BA.2 is not mild, as evidenced by mortality and serious complications in uninfected and unvaccinated children.” .
Get ready, but don’t be scared
Although the study findings may seem frightening, Dr. Claudia Hoyen, a pediatric infectious disease specialist at UH Rainbow Babies & Children’s Hospital in Cleveland, says parents should remember that “the odds of a child dying from omicrons are very, very very, very, very low,” he said.
According to data from the US Centers for Disease Control and Prevention (CDC), less than 0.1% of deaths from covid-19 in the US have been children. under 12 years old.
“I don’t think you should panic, given what we’ve seen in this study,” says Hoyen.
But it’s an indication that while “we’re all in the midst of a big sigh of relief here, at least in the United States, it’s not over,” he said. “We still have large groups of vulnerable populations.
“Parents of younger children may need to take more precautions than other families,” Hoyen said.
Thielen agrees. The best way for families to protect infants and toddlers is to make sure everyone around them is up-to-date on their shots, including boosters, she said. She noted that the shots were particularly beneficial for pregnant women because the antibodies in the vaccines protect both the carrier and the baby for a period of time after birth.
Breastfeeding is also protective because the antibodies pass to babies through breast milk.
And Thielen says high-quality masks on everyone in the family who can wear them is a good idea, too.