While countries like the United States and the U.K. are slowing down on vaccination rates for their own residents, the rates of individuals from other countries visiting them for the sole purpose of getting vaccinated against COVID-19 is rising.

A new video from the BCC explains that the abundance of extra vaccines in the U.S. is causing thousands of people from countries where vaccines are in rare supply to pay thousands of dollars to travel to get vaccinated.

San Francisco International Airport alone has vaccinated around 1,000 individuals from fifty different countries since May, according to the BCC. The airport has made vaccinations available for travelers from other countries who successfully pass customs and who are over 18 years of age. The program has been incredibly popular with those traveling to the U.S. from countries where vaccines are hard to find.

However, only those who have the money to travel here are getting vaccinated, citing a need for better and wider access in the countries with the lowest vaccination rates. Countries in places like Africa and Central and South America have extremely low rates of vaccination.

While the world’s fully vaccinated population is just under 15 percent, many of the vaccinated are from typically wealthy countries with the resources to purchase or manufacture vaccines, such as the United States.

Africa as a continent has less than two percent of its population completely vaccinated, according to the latest data from Our World in Data . South America’s total population is just under 19 percent fully vaccinated, though vaccination rates differ dramatically from country to country.

The Biden Administration has promised to donate 500 million vaccines to developing countries throughout the world, but distribution is going to be slow going, with many vaccines expected to ship in 2022.

It is unclear whether the Delta variant will inhibit vaccine tourism in the United States or enable it to grow as it continues to spread worldwide.