During late December 1948, men clearing jungle near Pacora, Panama, about 15 miles east of Panama City, contracted yellow fever. The Pan American Sanitary Bureau noted this as the first outbreak of the disease in 20 years. By January 1949, eight persons developed yellow fever symptoms and six died. Panama Canal Zone officials planned a vaccination campaign.
The United States Public Health Service stored yellow fever vaccine at its serum laboratory in Hamilton, Montana, just south of Missoula. They asked the Air Force to airlift serum to Panama. On January 16, the Fifteenth Air Force’s 92d Bombardment Wing at Spokane AFB, Washington, flew two B–29 Superfortresses to Missoula to pick up the vaccine and carry it to the Canal Zone. Engine trouble forced one plane to land at MacDill AFB, Florida. But the other B–29, belonging to the 98th Bombardment Group (Medium), completed the mission to the Canal Zone on January 16, delivering 75,000 doses of yellow fever vaccine.
The Panama Canal Zone Health Department inoculated U.S. military personnel, Panama Canal employees, and Panamanian citizens. By January 24, more than 30,000 people had been vaccinated against yellow fever, and the epidemic