KAMPALA, Uganda (AP) — Uganda has rolled out a nationwide yellow fever vaccination campaign to help safeguard its population against the mosquito-borne disease that has long posed a threat.

By the end of April, Ugandan authorities had vaccinated 12.2 million of the 14 million people targeted, said Dr. Michael Baganizi, an official in charge of immunization at the health ministry.

Uganda will now require everyone traveling to and from the country to have a yellow fever vaccination card as an international health regulation, Baganizi said.

Ugandan authorities hope the requirement will compel more people to get the yellow fever shot amid a general atmosphere of vaccine hesitancy that worries healthcare providers in the East African nation.

The single-dose vaccine has been offered free of charge to Ugandans between the ages of 1 and 60. Vaccination centers in the capital, Kampala, and elsewhere included schools, universities, hospitals and local government units.