PHOENIX (AP) — Arizona's seven state-run vaccination sites on Thursday began offering the Pfizer COVID-19 shot to children ages 12-15.

The move followed actions by federal health regulators to expand emergency authorizations for the vaccine.

Arizona has nearly 400,000 youths ages 12-15, representing nearly 5.6% of the state’s population.

“These safe, highly effective, and free vaccines have never been easier to get,” Dr. Cara Christ, the state's top public health official, said in a statement. “The sooner we can get as many people as possible vaccinated against COVID-19, the better we can protect people of all ages from this unpredictable virus.”

The expanded availability applies only to the Pfizer vaccine, which until now was only available to people ages 16 and older. The Moderna and Johnson & Johnson vaccines are authorized for people 18 and older.

Arizona has four state-run vaccination sites in metro Phoenix and one each in Flagstaff, Tucson and Yuma.

Appointments for vaccinations can be made online. The Department of Health Services said appointments aren't necessary but help save time at the site by registering beforehand,

The department said a parent or guardian must accompany children for the vaccines and sign a consent form in person, including an attestation that the child is at least 12 years old. No identification is required for the children, the department said.

The state on Thursday reported 544 additional confirmed COVID-19 cases and eight deaths, increasing the pandemic totals to 871,168 cases and 17,438 deaths.