Paediatric hospitalisations for Covid-19 have soared over the summer as the highly contagious Delta variant spread across the country, according to two new studies from the Centres for Disease Control and Prevention.

From late June to mid-August, hospitalisation rates in the US for children and teenagers increased nearly fivefold, although they remain slightly below January’s peak, one new study found.

But vaccination has made a difference. During this summer’s wave, the hospitalisation rate was 10 times as high in unvaccinated adolescents as in those who were vaccinated, researchers found. Paediatric hospital admissions were nearly four times as high in states with the lowest vaccination rates as in those with the highest rates, according to a second study.

The studies, released on Friday, do not provide clear answers about whether Delta causes more severe disease in children than earlier versions of the virus. The rise in paediatric hospitalisation could also be because of the variant’s high infectiousness.

Indeed, one study concluded that the proportion of hospitalised children with severe disease had not changed in late June and July, when the Delta variant became dominant in the US.

The rates reported in the CDC studies are based on data from two national surveillance systems, including hospitals in 49 states and Washington DC.

In one CDC study, researchers found that since July, when the Delta variant became predominant, the rate of new coronavirus cases increased for children 17 or younger, as did Covid-related emergency room visits and hospital admissions.

“We saw that ER visits, cases and hospital admissions are rising,” said David Siegel, lieutenant commander in the US Public Health Service and the lead author of the paper. “It could be that Delta is more severe or that Delta is more transmissible, and it could be related to other factors such as masking.”

Last month, as Delta surged, the incidence of Covid in children rose from earlier in the summer — reaching 16.2 cases per 100,000 children ages 4 or under; 28.5 cases per 100,000 children ages 5 to 11; and 32.7 cases per 100,000 children ages 12 through 17.

That rate represented a sharp spike from a June low of 1.7 per 100,000 children ages 4 or under; 1.9 cases per 100,000 children ages 5 to 11; and 2.9 per 100,000 children between ages 12 and 17. It was still below the peak incidence of cases among children last January.

The proportion of Covid patients under 17 who were admitted to intensive care units ranged from 10 to 25 per cent from August 2020 through last June, and hovered at 20 per cent by July 2021, according to the CDC study.

In a second study, researchers found that from March 1, 2020, to August 14, 2021 — there were 49.7 Covid-related hospitalisations per 100,000 children and adolescents.

New York Times News Service