The teens received their COVID-19 vaccine shots at Cohen Children's Medical Center on Thursday.
Dr. Sophia Jan, the Center's General Pediatrics Chief, said that the COVID-19 vaccines even among children are "nearly 100 percent effective against hospitalizations and death".
U.S. states are using the vaccine from Pfizer Inc and BioNTech SE to inoculate young adolescents against COVID-19 after advisers to the U.S. Centers for Disease Control and Prevention (CDC) backed the plan in an unanimous vote on Wednesday.
The U.S. Food and Drug Administration on Monday authorized the vaccine for children aged 12 to 15, offering relief to parents eager to get their children back to schools and summer camps.
The action by the CDC group is an important, but not required, final seal of federal regulatory approval.
The youngest age previously approved for the Pfizer vaccine was 16 years old.