Some international travelers could be impacted as the Centers for Disease Control and Prevention says the U.S.-licensed yellow fever vaccine supply will be depleted by mid-2017.

Last year, there was a manufacturing issue at Sanofi Pasteur that limited production of the vaccine.

No yellow fever vaccine is expected to be available by mid-2017. YF-VAX is the only yellow fever vaccine licensed for use in the United States.

"We are going to have very limited supply of the vaccine," says the CDC's Tom Skinner. He says people need to plan ahead if they are traveling to areas where the vaccine is required.

For most travelers, a single dose of yellow fever vaccine provides long-lasting protection and a booster dose of the vaccine is not needed. However, some travelers may require a booster dose.

Also, certain countries might require a booster dose of the vaccine.

Yellow fever is found in tropical and subtropical areas in South America and Africa. The virus is transmitted to people by the bite of a mosquito.

It is recommended that people be vaccinated against yellow fever if they are traveling to areas where it's transmitted in South America and Africa.

Yellow fever vaccine may be required for entry into certain countries. There are about 18 countries that will not allow you in unless you have proof you have been vaccinated against the virus.

The CDC says last year there were 42 countries that experienced outbreaks of yellow fever.