Omicron updates: COVID-19 cases could double in New York City

At least 25 states have now reported cases of the omicron variant, just over a week after California identified the first case in the U.S.

Iowa, Michigan and Virginia became the latest states Thursday to confirm positive cases of the new variant of concern.

Other states with confirmed cases include Arizona, Colorado, Connecticut, Florida, Georgia, Hawaii, Illinois, Louisiana, Maryland, Massachusetts, Minnesota, Mississippi, Missouri, Nebraska, New Jersey, New York, Pennsylvania, Texas, Utah, Washington and Wisconsin.

Centers for Disease Control and Prevention Director Rochelle Walensky told the Associated Press Wednesday that most of the cases have been mild, though there has been at least one hospitalization.

-ABC News' Arielle Mitropoulos

COVID-19-related hospital admissions in the U.S. are up by 47% in the last month, according to federal data. Nearly 80% of adult ICU beds are full.

The U.S. is now reporting more than 117,000 new cases each day. The daily case average has surged by nearly 83% since late October, according to federal data.

New Hampshire holds the nation's highest case rate, followed by Michigan, Minnesota, Rhode Island, New Mexico, Indiana, Vermont, Massachusetts and New York.

-ABC News' Arielle Mitropoulos

Over 2 million children ages 5 to 11 are now fully vaccinated, White House COVID-19 data director Cyrus Shahpar said.

These kids are among the over 200 million Americans of all ages who are now fully vaccinated, according to the White House.

Shahpar's tweet added, "Early evidence indicates boosters increase protection against Omicron. Get boosted!"

However, roughly two-thirds of parents of elementary school-aged children are either holding off on getting their younger kids vaccinated or refuse to do so, according to a poll released Thursday by the nonprofit Kaiser Family Foundation.

Parents of teens are more willing to get their kids vaccinated, but only about half of that age group have gotten the shot so far, KFF found.

The new findings come despite increasing evidence that the vaccine is safe and that kids and teens are now helping to drive up case numbers.

CDC director Rochelle Walensky has signed off on the recommendation for Pfizer boosters for 16- and 17-year-olds.

"Although we don’t have all the answers on the Omicron variant, initial data suggests that COVID-19 boosters help broaden and strengthen the protection against Omicron and other variants," Walensky said. "I strongly encourage adolescents ages 16 and 17 to get their booster if they are at least 6 months post their initial Pfizer vaccination series."

The FDA authorized Pfizer's booster for 16 and 17 year olds earlier on Thursday.

Pfizer CEO Albert Bourla called this a "critical milestone."

"While new variants, including Omicron, emerge across the globe, we believe that the best way to minimize the spread of COVID-19 and any future variants is getting all eligible people fully vaccinated with the first two dose series and a booster dose as recommended," he said in a statement.

-ABC News' Cheyenne Haslett, Eric M. Strauss