Is Delta Also More Severe in Kids?

With recent increases in COVID-19 cases and hospitalizations in children, some experts are concerned that the Delta variant may cause more severe illness in kids than previous variants.

Though the data remain in short supply, some have suggested it would be reasonable to extrapolate mounting evidence of increased severity with Delta in adults to children.

The CDC stated that some data suggest Delta may cause more severe illness in the unvaccinated. The agency called attention to two studies -- one from Scotland, one from Canada -- that showed patients infected with Delta were more likely to be hospitalized than those infected with other variants.

David Kimberlin, MD, a pediatric infectious disease expert at the University of Alabama and a member of the American Academy of Pediatrics' (AAP) Committee on Infectious Diseases, said that "while we don't know if those data apply to children, the anecdotal information suggests it might."

"Across the South, where we have low vaccination rates, children's hospitals are experiencing many more cases than they did at the worst of the peak at the end of 2020 and the beginning of 2021, suggesting it's possible that Delta causes more severe disease in children," he told MedPage Today.

Even if the virus isn't more severe in kids, Kimberlin said, "we're still staring down the barrel of this gun because its hypertransmissibility is causing more pediatric infections than earlier versions did."

That's a particular concern as children in the South have returned or are starting to return to classrooms, he noted.

The latest AAP data show a sharp increase in COVID-19 cases in kids, totaling 94,000 in the week ending August 5 -- up from almost 72,000 cases the week prior, and 39,000 cases the week before that. Previously, the most recent nadir was approximately 8,500 cases for the week ending June 24.

The highest peak of pediatric COVID infections occurred during one week in mid-January -- 211,000 cases. So far, nearly 4.3 million kids in the U.S. have contracted COVID-19 since the start of the pandemic, and they account for 14.3% of all U.S. cases cumulatively. This past week, they accounted for 15% of cases.

As for hospitalizations, which the AAP tracks in 23 states and New York City, kids accounted for 1.5% to 3.5% of total cumulative hospitalizations, and 0.1% to 1.9% of all pediatric COVID cases resulted in hospitalization.

CDC's COVID Data Tracker shows a total of about 46,000 hospital admissions for kids under 18 since Aug. 1, 2020, with a current 7-day average of 203 pediatric hospitalizations daily -- close to the peak 7-day average of 217 during this past winter's surge (for the week ending Jan. 9, 2021). This week's figure is up from a 7-day average of 168 the week prior.

AAP collects mortality data from 43 states, New York City, Puerto Rico, and Guam, tallying 371 pediatric deaths since mid-May 2020.

Children accounted for 0% to 0.26% of all COVID deaths in those areas, and seven states reported no child deaths at all. Of all pediatric COVID cases in those areas, 0% to 0.03% resulted in death.

"At this time, it appears that severe illness due to COVID-19 is uncommon among children," the AAP report stated. "However, there is an urgent need to collect more data on longer-term impacts of the pandemic on children, including ways the virus may harm the long-term physical health of infected children, as well as its emotional and mental health effects."

During an Infectious Diseases Society of America (IDSA) press briefing last week, Ezekiel Emanuel, MD, PhD, of the University of Pennsylvania in Philadelphia, cautioned that it's difficult to tease apart severity data in general because increasing hospitalizations could just be the result of increasing cases due to Delta's greater transmissibility.

But Emanuel acknowledged anecdotal reports suggesting a more rapid progression of illness compared with the early days of the pandemic. And experts on the ground in hard-hit areas have described greater challenges now compared with previous waves.

Last week, Mark Kline, MD, chief physician at Children's Hospital New Orleans, told ABC News that the positivity rate in kids rose from 1% to about 20% over the last 30 days.

"We are hospitalizing record numbers of children," Kline said, adding that the majority are under 12 and can't yet be vaccinated.

In Alabama, Kimberlin noted that "our hospitals are close to complete capacity, and that includes children's hospitals in Mobile and Birmingham."

"We're deferring scheduled procedures," he said. "There are people who need cancer surgery that's being put off because there's no guarantee we'll have a bed available for them. People with heart attacks don't have beds. A child with vehicular trauma doesn't have a place to go because we're full."

"I think the rate of increase we see in pediatric cases is truly alarming," he added. "We've seen a skyrocketing of cases in a very short period of time. It's Delta. It's hypertransmissible. Combine that with the fact that two-thirds of our population [in Alabama] are not vaccinated -- that's not even touching on the kids under 12 who are not able to be vaccinated -- and you have a recipe for disaster."

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