Pharmacist LaChandra McGowan prepares a dose of the Pfizer COVID-19 vaccine at a clinic operated by DePaul Community Health in New Orleans in August. Soon, children ages 5 to 11 could be eligible for Pfizer shots. Mario Tama/Getty Images hide caption
A health care worker administers a Pfizer-BioNTech COVID-19 vaccine Thursday at Life of Hope Center in New York City. Michael M. Santiago/Getty Images hide caption
A health care worker prepares a dose of the Moderna COVID-19 vaccine during a clinic held at the Watts Juneteenth Street Fair in the Watts neighborhood of Los Angeles. Patrick T. Fallon/AFP via Getty Images hide caption
Janet Gerber, a health department worker in Louisville, Ky., processes boxes containing vials of the Johnson & Johnson COVID vaccine in March. Jon Cherry/Getty Images hide caption
A nurse prepares a dose of the Moderna COVID-19 vaccine at a San Antonio senior center in March. A panel of advisers to the Food and Drug Administration will meet Thursday to review Moderna's booster shot. Sergio Flores/Getty Images hide caption
One thorny issue facing President Biden at the United Nations: the defense deal he announced with Australia and the U.K., which left France so angry it pulled its ambassador from Washington, D.C. Win McNamee/Getty Images hide caption
A syringe with the Pfizer COVID-19 vaccine is prepared at a mobile vaccine clinic in Santa Ana, Calif., in August. An international group of scientists is arguing the average person doesn't need a COVID-19 booster yet — an opinion that highlights the intense scientific divide over the question. Jae C. Hong/AP hide caption
A third shot of the Moderna vaccine boosts protection across age groups, notably in older adults, the company says. Juana Miyer/Long Visual Press/Universal Imag hide caption
A COVID-19 vaccine dose is prepared at a pharmacy in Baton Rouge, La., on Aug. 17. About 14 million people received their first dose of a COVID-19 vaccine in August. Mario Tama/Getty Images hide caption
Medics in Jerusalem transfer a COVID-19 patient to Hadassah Hospital Ein Kerem. Many hospitals in Israel are at full capacity following a sharp increase in coronavirus infections. Menahem Kahana/AFP via Getty Images hide caption
Containers of Moderna vaccines donated by the U.S. arrive last week in Bogotá, Colombia. Leonardo Munoz/AFP via Getty Images hide caption
Tanzania's President Samia Suluhu Hassan receives her Johnson & Johnson vaccine against the coronavirus at the statehouse in Dar es Salaam on July 28. Her administration has reversed the government's anti-vaccination stance. Emmanuel Herman/Reuters hide caption
First lady Jill Biden tours a vaccination site in Nashville with country star Brad Paisley and his wife Kimberly Williams-Paisley. Jason Kempin/Getty Images hide caption
The challenge of refrigerating COVID-19 vaccines is acute in sub-Saharan Africa, where only 28% of health care facilities have reliable power. Jason Beaubien/NPR hide caption
Vaccine doses are in short supply in African countries — and even when they arrive, there may not be a way to get them into people's arms in a timely fashion. Above: People wait to get vaccinated at a hospital in Thika, Kenya, in March. Patrick Meinhardt/Bloomberg via Getty Images hide caption