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)

Vaccinators wear protective masks as they get their temperature checked, during an anti-polio campaign, in a low-income neighborhood as the spread of the coronavirus disease (COVID-19) continues, in Karachi, Pakistan on July 20, 2020. (Photo by Akhtar Soomro/Reuters)

Coronavirus vaccinated audience members watch Saudi prominent singer Mohammed Abdu as he performs at the newly built Super Dome, in Jiddah, Saudi Arabia, late Thursday, July 8, 2021. The concert is organized by the Saudi General Entertainment Authority after the kingdom lifted coronavirus restrictions on events in May. (Photo by Amr Nabil/AP Photo)

Participants celebrate the awakening of the Hoppeditz, a fictional character whose return to life marks the start of the carnival season in Düsseldorf, western Germany on November 11, 2021. The 11.11. is celebrated this year again under Corona conditions in presence. However, in the carnival strongholds of Cologne and Düsseldorf, this only applies to the vaccinated and the recovered. (Photo by Federico Gambarini/dpa/Alamy Live News)

Yi Arias, a CORE crew member in an upbeat mood at COVID-19 mass-vaccination of healthcare workers taking place at Dodger Stadium in Los Angeles, California, U.S., January 15, 2021 (Photo by Irfan Khan/Pool via Reuters)

In this May 21, 2021, file photo, JoJo Hamner, a cast member of the “Sexxy After Dark: Where Dinner Meets Play” show, gets the Pfizer COVID-19 vaccine during a pop-up vaccine clinic at Larry Flynt's Hustler Club in Las Vegas. It's one of several methods health officials are employing here and across the country to bring vaccines directly to people to counter waning demand. In tiny towns, ballparks, strip clubs, and marijuana dispensaries, officials are setting up shop and offering incentives to entice people who so far have not gotten shots. (Photo by Ellen Schmidt/Las Vegas Review-Journal via AP Photo/File)