Pfizer-BioNTech, Oxford-AstraZeneca, Sputnik V, and Sinopharm are among the authorized vaccines being distributed in multiple countries.
But Russia, India, and China have been criticized for rushing their vaccine approval processes, and some people remain skeptical about getting inoculated.
As wealthier nations expand their immunization efforts, many developing countries struggling with the pandemic are still waiting for their shots.
Mobile freezers brought onto boats and carried by motorbikes this is what it takes to deliver measles and Ebola vaccines to remote parts of Congo.
The efforts were essential to control those outbreaks, and they can teach us lessons on how to bring the new COVID-19 vaccines to billions of people living in isolated areas of the world.