Admissions at some U.S. children's hospitals are rising to near peak levels as Omicron spreads

(CNN) -- As the Omicron variant continues to grip the US, some children's hospitals are once again seeing a rise in admissions fueled by the most contagious strain of coronavirus yet.

The holidays this year accompanied bya surge in Covid-19 cases that is so high it surpassed a record set earlier this year. On Tuesday, the US hit a seven-day average of 265,427 new Covid-19 cases daily, Johns Hopkins University data shows -- eclipsing the previous record of about 251,989 daily cases reported on January 11.

The rise in infections is reflected in admissions at pediatric wards in parts of the country. An average of 305 children were fighting Covid-19 in a hospital on any given day during the week ending December 26, according to data from the Centers for Disease Control and Prevention (CDC) and the US Department of Health and Human Services (HHS).

The sobering figure is a more than 48% increase from the previous week and 10.7% lower than the peak average of 342 children who were admitted to hospitals with the virus at the end of August and early September.

And while everyone ages 5 and older in the US is eligible to receive a vaccine, about 40% of the total population is not fully vaccinated, putting them at a higher risk for Covid-19's most severe outcomes, including serious illness and death.

The number of children who need medical attention at Children's National Hospital in Washington, D.C, has nearly doubled, according to Roberta DeBiasi, the division chief of infectious diseases at the hospital.

DeBiasi explained that her hospital admitted about 20 children at its peak, but that number has jumped to between 40 and 50 during the Omicron surge. She also noted that most of the patients are unvaccinated, partially vaccinated or immunocompromised.

"So that is really the big difference, and it's not because the virus is more severe. It's because the overall infectivity and number of cases has really shot up," DeBiasi said.

Even so, she said hospital staff have been able to keep the mortality rate low.

"Even our children that are extremely ill, critically ill, we've gotten very good at taking care of these children," she said.

In New York City, pediatric hospitalizations increased five-fold over a three-week period.

And at the Lurie Children's Hospital of Chicago, Covid-19 cases are roughly three times higher than the hospital's previous peak in December 2020. In the past week, hospitalizations are four times higher what the hospital typically sees.

Overall, experts are warning the next few weeks will be rough for the country in terms of handling yet another Covid-19 surge.

"There's no question that January will be filled with a lot of short-term challenges. Hospital beds, staffing shortages, tests, shortages of almost everything. It's tough for the system to handle this many cases at once," Andy Slavitt, former senior adviser to the Biden Administration's Covid-19 response team, told CNN's Jim Acosta Tuesday.

At-home testing kits less sensitive to Omicron, FDA says

Millions of Americans have turned to at-home Covid-19 tests as a precautionary measure before traveling or gathering for the holidays. Experts and officials alike have been pushing for people to get tested before getting together, especially indoors.

But the US Food and Drug Administration (FDA) said Tuesday that quick antigen tests may have less to detecting the Omicron variant.

Studies on antigen tests that used patient samples that had the live virus showed that while the tests detect the Omicron variant, they did so with less sensitivity, the FDA said. Sensitivity measures how often a test can give a positive result when someone has the disease.

More studies on the tests are ongoing, and the FDA says people should continue using them.

"The tests are still worthwhile. Don't let anybody think that the FDA was saying that tests are no longer good, Dr. Anthony Fauci, director National Institute of Allergy and Infectious Diseases, said Tuesday. "They say they're less sensitive now. They never were 100% sensitive," Fauci told CNN's Michael Smerconish.

"What the FDA is saying today is that when you look at Omicron and its ability to detect Omicron, some of the tests have a diminution further of the sensitivity, but they still say the tests are useful and should be used," Fauci explained.

Some schools should consider delaying return after holidays, expert says

As Covid-19 cases surge, areas where there's a high level of transmission should think twice about returning to in-person learning following the holiday break, Dr. Peter Hotez, dean of the school of tropical medicine at Baylor College of Medicine, said Tuesday.

"I wouldn't do it now," Hotez told CNN's Poppy Harlow. "You have got a screaming level of transmission in the Northeast, in New York City and Washington, D.C. Trying to open schools at this point, it's hard to imagine how things will go well."

He added, "There's just too high a level of virus transmission when you are talking about a virus that may be as transmissible as measles among a mostly unvaccinated population and so, that's going to be very rough."

New York City and DC have both seen record high Covid-19 cases in recent days.

New York State broke its single-day positive Covid-19 case record on Sunday, reporting 49,708 positive cases on Christmas Eve -- effectively topping the state's previous record high of 44,431, according to data released Sunday by Gov. Kathy Hochul's office.

In DC, 1,904 new Covid-19 cases were reported last Wednesday -- surpassing the record set the previous day, when 1,524 positive coronavirus cases were recorded.

Still, New York City public schools, which is the largest public school system in the country, will reopen as planned on January 3 following a winter recess, Mayor Bill de Blasio said Tuesday.

The city is revamping its Covid-19 testing policies in an attempt to keep more students in school during the latest surge, de Blasio said.

Schools will be provided at-home testing kits for classrooms when a student has tested positive, and students will take two tests per day over seven days, de Blasio said. With this new policy, any student who doesn't have symptoms and tests negative after one day of two rapid tests will return to school the next day, he continued.

The previous policy mandated that fully vaccinated students identified as close contacts did not have to quarantine if they were symptom-free and tested, but unvaccinated students had to quarantine for 10 days or test out.