The shortage of vaccines and slow vaccine rollouts in many parts of the world, has sparked a trend of vaccine tourism, with many tourists heading to the United States to get vaccinated.
Nearly 50% of US residents are fully vaccinated but the rates are much lower in many countries.
The BBC’s Cindy Sui has been speaking to some ‘vaccine tourists’ at San Francisco International Airport, where anyone who is allowed to pass through customs can get a free shot as long as they do not currently have Covid, have not had another Covid vaccination and are at least 18 years old.