Workers check oxygen tanks at a hospital in Manaus, Brazil. Severe oxygen shortages as a second coronavirus wave is surging have prompted local authorities to airlift patients to other parts of Brazil. Jonne Roriz/Bloomberg via Getty Images hide caption
A coronavirus variant that is thought to be more contagious was detected in the United States in Elbert County, Colo., not far from this testing site in Parker, Colo. The variant has been detected in several U.S. states. Michael Ciaglo/Getty Images hide caption
Volunteers and health officials hold a dry run for the coronavirus vaccine at a hospital in Allahabad, India. There's concern that drug patents will keep lower income countries from getting the doses they need in a timely fashion. Sanjay Kanojia/AFP via Getty Images hide caption
The image depicts the coronavirus binding to a human cell. The variant identified in the United Kingdom has a mutation known to increase how tightly the virus binds to human cells. Kateryna Kon/Science Photo Library via Getty Images hide caption
A poster about the new, fast-spreading variant of the coronavirus warns some Britons to stay home. The sign is displayed near King's Cross railway station in London. Jason Alden/Bloomberg via Getty Images hide caption
Dr. Chizoba Barbara Wonodi is director of Johns Hopkins University's International Vaccine Access Center for Nigeria. Dr. Chizoba Barbara Wonodi hide caption
A female Aedes aegypti mosquito feeds on human skin. James Gathany/CDC/Smith Collection/Gado/Getty Images hide caption
The pharmaceutical company Pfizer, and its partner BioNTech said their experimental vaccine against COVID-19 appears to work — and work quite well. Matt Stone/MediaNews Group via Getty Images hide caption
Health workers measure a woman's blood pressure during a simulation of a COVID-19 vaccine trial in Indonesia. Adriana Adie/NurPhoto via Getty Images hide caption