Originally Published: 22 SEP 23 17:34 ET

By Jamie Gumbrecht, Deidre McPhillips and Betsy Klein, CNN

(CNN) — Covid-19 hospitalizations have been on the rise in the United States for months, with weekly admissions now more than triple what they were two months ago. Seniors have the highest rates of Covid hospitalizations by far, but hospitalizations among children — especially among those younger than 5 — are rising fast.

More than 20,500 people in the US were admitted to the hospital with Covid-19 during the week ending September 9, according to data from the US Centers for Disease Control and Prevention – about 8% higher than the week before.

“We haven’t really seen this for many months, but we’re starting to see people come into the hospital critically ill,” said CNN medical analyst Dr. Jonathan Reiner, a cardiologist and professor of medicine and surgery at George Washington University. “There needs to be a greater sense of urgency because deaths are rising, hospitalizations are rising.”

On Friday, a White House official acknowledged increased infections and hospital admissions nationally, but noted that levels remain lower than during past Covid surges. The Biden administration is also preparing to ramp up messaging on flu, RSV and Covid vaccines, including for higher-risk populations such as seniors and young children.

“We are tracking upticks in some parts of the country but believe we remain in the strongest position yet as we head into fall,” the White House official told CNN.

Who’s hospitalized now

Nationally, more than half of new Covid-19 hospital admissions were among people age 70 and older, and more than two-thirds are among people age 60 and older, according to the latest CDC data.

But a new analysis of federal data from the American Academy of Pediatrics showed hospital admissions among children are rising faster than average. Nearly 1,200 children were admitted to the hospital with Covid-19 during the week ending September 9, marking a five-fold increase over the past three months. Hospitalizations among adults increased about three-fold in that same time period.

Admissions among children remain below previous pandemic peaks. There were about 1,800 new pediatric admissions in a week at the height of last winter’s wave, and more than 6,500 weekly admissions during Omicron, the AAP analysis shows.

Children accounted for 6% of all Covid-19 hospital admissions during the week ending September 9, federal data shows. And children under 5 were the most at risk, with about half of all pediatric Covid-19 hospitalizations among those younger than 5, according to the AAP analysis.

“This increase in hospitalizations, especially for the youngest children, is very concerning,” said Dr. Sandy L. Chung, president of the AAP. “We know this is the age group with the lowest vaccination rates. Right now, we have updated COVID vaccines that can help children’s immune systems learn to detect and resist the virus, including the strain that is circulating now. The virus is still here, and I’d urge parents to talk with their pediatricians about how they can protect their family.”

Vaccination rates have consistently lagged for children. In May, when the public health emergency ended, less than 1% of children under 5 had received the bivalent booster and less than 10% of children ages 5 to 17 had received it, data from the CDC shows.

Covid-19 remains the main virus of concern as the US heads into respiratory virus season, representing nearly all virus-associated hospitalizations since the beginning of the year. But RSV levels have started to pick up in most regions of the US.

Dr. Susan Walley, chief of the Division of Hospital Medicine at Children’s National Hospital in Washington, D.C., said they’ve seen in increase in hospitalized patients testing positive for all respiratory viruses, including Covid-19, since early September.

“It’s not unusual, unfortunately, for there to be an increase in children hospitalized with respiratory symptoms at the start of the school year, and it demonstrates the importance of all children who are eligible to get the COVID-19 and influenza vaccine,” Walley said in a statement.

Where hospitalizations are highest

For now, Covid-19 hospitalizations remain concentrated in the South. Florida had a higher hospitalization rate than any other state — 11 per 100,000 people in one week — and about 11% of all Covid-19 hospital admissions in the first week of September were in Florida.

After Florida, Washington, DC, had the highest rate of hospital admissions, about 10 per 100,000 people in one week. Arkansas, Alabama, Louisiana and West Virginia also among states with the highest hospitalization rates.

CDC guidance around masking is based on hospitalization metrics, and more than half of Florida’s counties fall into a category where masking is recommended for all high-risk individuals. More than two dozen counties in Arkansas, Kentucky, Texas and Georgia also fall into this category. Overall, masking is recommended at least for high-risk individuals in about 1 in 8 counties.

Despite the recent increases, Covid-19 hospitalizations are still roughly half of what they were during last winter’s peak. Virus levels are even starting to recede in parts of the country – especially the South – and the pace of increase is starting to slow nationwide.

Shifts in testing practices have made case counts less reliable, but tracking virus levels in wastewater can help gauge transmission. Levels have been on the rise nationwide since late June, but have started to tick down in September. The decrease is most pronounced in the South, where viral concentrations dropped about 25% in the first two weeks of the month.

However, CDC forecasting models suggest that weekly hospitalization rates will continue to rise, most likely to double what they are now by the season’s peak in December.

White House ramps up Covid-19 messaging

The Biden administration said Friday it’s working on community, stakeholder and digital outreach, including to physicians and other health care providers. Earlier this week, the administration announced Covidtests.gov will reopen on Monday for households to request four free Covid-19 tests.

It’s also preparing to ramp up messaging on Covid-19, flu and RSV vaccines.

“We will be encouraging all Americans to get those boosters in addition to flu shots, as well as the RSV immunization for people over 60 and for infants,” the White House official said.

US Health and Human Services Sec. Xavier Becerra and CDC Director Dr. Mandy Cohen are both hitting airwaves to press the importance of vaccines. Speaking on CNN on Friday, Cohen emphasized there are safe, effective strategies available to reduce risk, including washing hands, staying home when sick, improving ventilation, wearing a mask and getting vaccinated.

Flu vaccines are already broadly available in pharmacies and doctor’s offices. For the first time, there are vaccines available against RSV for people age 60 and older, and the US Food and Drug Administration recently approved a maternal vaccine and an antibody product that can protect infants.

Updated Covid -19 vaccines by Pfizer and Moderna are starting to roll out across the country, and are recommended for everyone 6 months and older.

“It’s important to know your own risk,” Cohen said. “Are you around folks who are older or who have underlying conditions? Then we need to use more layers of protection.

“The fact is we have tools, we need to use them.”

CNN’s Jen Christensen and John Bonifield contributed to this report.