By Carl O’Donnell and Maria Caspani

(Reuters) -The United States on Wednesday began administering the COVID-19 vaccine to children ages 5 to 11, the latest group to become eligible for the shots that provide protection against the illness to recipients and those around them.

On Tuesday, the U.S. Centers for Disease Control and Prevention recommended the Pfizer Inc/BioNTech SE shot for broad use in that age group.

Only a limited number of the 15 million shots being distributed now will be available on Wednesday. They are expected to be more widely accessible at pediatrician’s offices, children’s hospitals and pharmacies next week.

The big national pharmacy chains, Walgreens Boots Alliance, CVS Health and Rite Aid are among those offering appointments for this weekend.

Virginia Commonwealth University Health received the vaccine on Tuesday but will probably not start administering it until next week because of logistics and safety protocols, Director of Pharmacy Services Rodney Stilner told Reuters.

“For us to be able to receive the vaccine and even start today would just be like, almost impossible,” he said.

While about 58% of Americans are fully vaccinated against COVID-19, some 28 million children under 12 have not been eligible until now.

The 10-microgram shot of the Pfizer/BioNTech vaccine authorized for school-age kids – a third the strength given to adolescents and adults – offers protection from the Delta variant of the virus that has led to thousands of pediatric hospitalizations.

‘MUCH EASIER, MUCH SAFER’

The vaccine, shown to be more than 90% effective at preventing symptomatic infection in children, also provides an avenue for fewer quarantines or school closures and more normal activities and freedoms.

“I think it’s going to make the issue of schools much easier, much safer,” White House chief medical adviser Dr. Anthony Fauci said in an interview with CNN on Wednesday.

Still, it remains unclear how many parents will jump at the chance. Even many who have been vaccinated themselves are more divided over whether to vaccinate their own younger children, given that severe COVID-19 is much less common for them.

There were no new safety issues in Pfizer’s study of the vaccine in thousands of children, but there is also no long-term data for its use.

The U.S. Food and Drug Administration authorized the Pfizer/ BioNTech vaccine for children aged 5 to 11 years on Friday. A few other countries, including China, are already vaccinating children. The European Union and Canadian regulators are currently considering Pfizer’s application for the vaccine in this younger age group.

So far, only Pfizer’s shot has been authorized for use in the United States for those under age 16.

Moderna Inc has delayed its request for authorization for its vaccine for children aged 6 to 11 and is waiting on an FDA review of safety data in connection with its application for 12- to 17-year old’s.

The states with the highest adult COVID-19 vaccination rates are preparing bigger pushes to get children inoculated than states where hesitancy remains strong, potentially widening the gaps in protection nationwide, public health officials and experts said.

COVID-19 vaccines have emerged as yet another issue exposing deep political fault lines in the United States that led to opposing stances on vaccinations, face covering and other pandemic restrictions in various parts of the country.

California, New York and Washington state, all led by Democratic governors who have promoted vaccination and mask-wearing, are setting up mobile sites and high-volume vaccination clinics for children, spokespeople for the public health departments of those states said.

California has also mandated that school-age children get a COVID-19 vaccine once their age group is eligible, a measure being considered in New York and Washington.

Republican state governors have largely resisted measures such as mask mandates or vaccine requirements in workplaces, schools and public venues. More than a dozen states, including Florida and Texas, have tried to block schools from imposing such requirements themselves.

(Reporting by Carl O’Donnell; additional reporting and writing by Maria Caspani; Editing by Caroline Humer, Jonathan Oatis and Bill Berkrot)