COVID-19 updates: 70% of American adults fully vaccinated

"We've taken the time to get this right," CDC director Rochelle Walensky told "Good Morning America" Wednesday, the day after she signed off on the Pfizer vaccine for young kids. "It's taken us almost a year compared to where we had a vaccine for adults."

Parents should have peace of mind with the vaccine's safety, she argued. "We reviewed the evidence, we reviewed the safety profile," she said.

"You may have questions, and we are here to answer your questions," she said. "Go talk to your pediatrician, your trusted health care provider, your pharmacist, and get the information that you need."

President Joe Biden called Tuesday's move by the Centers for Disease Control and Prevention to allow Pfizer COVID-19 vaccinations for children 5 to 11 years old "a turning point."

"It will allow parents to end months of anxious worrying about their kids, and reduce the extent to which children spread the virus to others," he said in a statement. "It is a major step forward for our nation in our fight to defeat the virus."

The president said his administration has secured enough pediatric vaccines for every child in America and has begun shipping out doses.

"The program will ramp up over the coming days, and fully up and running during the week of November 8," he said.

-ABC News' Anne Flaherty

U.S. Centers for Disease Control and Prevention Director Rochelle Walensky approved the agency's recommendations for administering the Pfizer COVID-19 vaccine to children between 5 and 11 years old.

Vaccinations for this age group, which includes over 28 million children, can begin as early as Wednesday morning.

The two-dose vaccine has been approved for an emergency use for children 12 to 15 years old and for full authorized use for patients above 16 years old.

Hartford HealthCare was one of the first locations in the country to administer the vaccine to kids Tuesday evening. The young patients cheered and gave doctors high fives after they received their shots.

-ABC News' Eric Strauss

Two major pharmacy chains announced Tuesday evening they are getting ready to offer Pfizer COVID-19 shots to children 5 to 11 years-old.

Pending signoff from U.S. Centers for Disease Control and Prevention Director Dr. Rochelle Walensky, which could happen as early as Tuesday night, Walgreens told ABC News it expects to begin administering shots to that age group starting Saturday.

Walgreens said its online scheduler for children's appointments will be available starting Wednesday.

The Pfizer pediatric vaccine will arrive "later this week in select locations throughout the country," CVS said in a statement. Appointments will be available at individual stores after each receives vaccines.

-ABC News' Sasha Pezenik