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)

A Garba (folk dance) participant gets her back painted with an awareness message on vaccination against the Covid-19 coronavirus during the ongoing Navratri festival in Ahmedabad in western India on October 8, 2021. (Photo by Sam Panthaky/AFP Photo)

A sеx worker protests at Rua Guaicurus, the main bohemian area of Belo Horizonte, state of Minas Gerais, Brazil on April 5, 2021, asking to be considered a priority group to receive the vaccine agaisnt COVID-19. (Photo by Douglas Magno/AFP Photo)

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)

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)

A little girl holding her newborn sister waits for their turn in a queue during a vaccination campaign under the supervision of the Syrian Arab Red Crescent (SARC) humanitarian nonprofit organization, in the besieged Syrian town of Douma, Syria, 23 May 2017. According to a statement from SARC, in the city of Douma some 12,809 children under the age of five were immunized in a vaccination campaign to prevent measles and poliomyelitis. The campaign was the first of its kind with the participation of 100 volunteers. SARC has been delivering vaccines to 17 health centers approved for vaccination campaigns in towns and villages in the Eastern Ghouta area. (Photo by Mohammed Badra/EPA)