In this photograph taken on February 18, 2016, Pakistani children ride on swings in the predominantly Pashtun Korangi District of Karachi. In a rundown district of Karachi, Rabia balks at a neighbour's proposal to vaccinate her children, demonstrating one of the biggest hurdles to eradicating polio in Pakistan by the end of the year: confused and frightened parents. (Photo by Asif Hassan/AFP Photo)

A school girl reacts as a health worker inoculates her with the dose of Pfizer-BioNTech vaccine against the Covid-19 coronavirus for the 12-15 years age group at an educational institution in Colombo on January 7, 2022. (Photo by Ishara S. Kodikara/AFP Photo)

Revellers at the Chin Chin music festival in Amsterdam, Netherlands on July 3, 2021. The festival season has started with a QR code, one can enter, corona proof or vaccination proof in the corona check app. (Photo by Robin Utrecht/Rex Features/Shutterstock)

President Joe Biden holds a baby as he visits a COVID-19 vaccination clinic at the Church of the Holy Communion Tuesday, June 21, 2022, in Washington. (Photo by Evan Vucci/AP Photo)

A woman reacts as she receives the AstraZeneca/Oxford vaccine under the COVAX scheme against coronavirus disease (COVID-19) at the Kenyatta National Hospital in Nairobi, Kenya on March 5, 2021. (Photo by Monicah Mwangi/Reuters)

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

A New Orleans Saints fan parties in the stands in the first half of an NFL preseason football game against the Jacksonville Jaguars in New Orleans, Monday, August 23, 2021. Last season the team played with a marginal number of fans in a largely empty Superdome due to the coronavirus pandemic, but this year fans are allowed with proof of vaccination. (Photo by Derick Hingle/AP Photo)

A health worker shows an empty syringe after inoculating a woman with AstraZeneca's COVID-19 vaccine during the first day of a nationwide three-day vaccination drive at a school in Quezon city, Philippines on Monday, November 29, 2021. There has been no reported infection so far caused by the new variant in the Philippines, a Southeast Asian pandemic hotspot where COVID-19 cases have considerably dropped to below 1,000 each day in recent days, but the emergence of the Omicron variant has set off a new alarm. (Photo by Aaron Favila/AP Photo)