More than 61,000 children in the U.S. were diagnosed with COVID-19 last week — more than in any other week during the pandemic, the American Academy of Pediatrics and the Children's Hospital Association reported Monday. In all, 853,635 children have been diagnosed with the virus this year, representing 11.1% of all U.S. cases. The percentage of pediatric cases has risen steadily since mid-April, when children accounted for just 2% of COVID-19 cases in the country.