Stickers are placed at the vaccine stations to be given to children aged 5-11-after receiving the Pfizer-BioNTech coronavirus disease (COVID-19) vaccine in Collegeville, Pennsylvania, U.S., November 6, 2021.

A girl receives her first coronavirus disease (COVID-19) vaccination after the country approved vaccinations for children aged 5-11, in Jerusalem November 23, 2021.

Noah Starling, 7, shows off the sticker he received following his first COVID-19 vaccination at Eastern Middle School in Silver Spring, Maryland, U.S., November 6, 2021.

A girl receives her first coronavirus disease (COVID-19) vaccination after the country approved vaccinations for children aged 5-11, in Jerusalem November 23, 2021.

Five year-old Milo from Chula Vista, California, receives the Pfizer-BioNTech coronavirus vaccine at Rady's Children's hospital vaccination clinic in San Diego, California, U.S., November 3, 2021.

A child reacts while receiving a dose of the Pfizer-BioNTech coronavirus disease (COVID-19) vaccine at Smoketown Family Wellness Center in Louisville, Kentucky, U.S., November 8, 2021.

Kyla Drumm, 5, waits after receiving the Pfizer-BioNTech coronavirus disease (COVID-19) vaccine in Skippack, Pennsylvania, U.S., November 3, 2021.

A woman dressed as Elsa cheers on Kate Rhodes and her mom Emma Rhodes as health workers with Humber River Hospital hold a vaccination clinic after Canada approved Pfizer's coronavirus disease (COVID-19) vaccine for children aged 5 to 11, in Toronto, Ontario, Canada November 25, 2021.

A girl receives her first coronavirus disease (COVID-19) vaccination after the country approved vaccinations for children aged 5-11, in Jerusalem November 23, 2021.

Eli Stern prepares to get his shot at a Humber River Hospital vaccination clinic after Canada approved Pfizer's coronavirus disease (COVID-19) vaccine for children aged 5 to 11, in Toronto, Ontario, Canada November 25, 2021.

Yoav, 9-years-old, receives his first coronavirus disease (COVID-19) vaccination, after the country approved vaccinations for children aged 5-11, in Tel Aviv, Israel November 22, 2021.

Nurse Nathalie Ngoh cheers after Noah Starling, 7, received his first COVID-19 vaccination at Eastern Middle School in Silver Spring, Maryland, U.S., November 6, 2021.

Cadence Pampena, 9, held by her mother, Brenna Pampena, receives the first dose of the Pfizer-BioNTech coronavirus disease (COVID-19) vaccine from Iman Yunis of Othello Station Pharmacy, during a Seattle Public Schools' school-day clinic at Bailey Gatzert Elementary in Seattle, Washington, U.S., November 8, 2021.

Maya Griesemer, 7, receives a first dose of the Pfizer-BioNTech coronavirus disease (COVID-19) vaccine from Seattle Public Schools' school-day clinic at Bailey Gatzert Elementary in Seattle, Washington, U.S., November 8, 2021.

Levi Forst, 7, receives the Pfizer-BioNTech coronavirus disease (COVID-19) vaccine in Skippack, Pennsylvania, U.S., November 3, 2021. Image used for illustrative purpose.

A prepared dose of the Pfizer-BioNTech coronavirus vaccine (COVID-19) for 5-11 year olds is seen in Storrs, Connecticut, U.S., November 3, 2021.

Five year-old Renan Rojas sits on his mom, Daniela Cantano's lap, as he receives the Pfizer-BioNTech coronavirus vaccine from registered nurse Jillian at Rady's Children's hospital vaccination clinic in San Diego, California, U.S., November 3, 2021. Image used for illustrative purpose.

Gal, 11, waits to receive her first coronavirus disease (COVID-19) vaccination after country approves vaccinations for children aged 5-11, in Tel Aviv, Israel November 22, 2021. Image for illustrative purposes.

Wesley Farin, 7, receives the Pfizer-BioNTech coronavirus disease (COVID-19) vaccine while being held by his father in Collegeville, Pennsylvania, U.S., November 6, 2021.