Yellow Fever 1942

About Yellow Fever 1942

During World War II, yellow fever vaccination of US troops caused an unexpected disaster. The yellow fever vaccine used human serum as a stabilizer. Some serum was contaminated with hepatitis B virus. Approximately 50,000 vaccinated troops developed clinical hepatitis, and dozens died. The incident, known as the 1942 hepatitis epidemic, was one of the largest iatrogenic disease outbreaks in history. The responsible virus, hepatitis B, was only characterized decades later. The incident led to the elimination of human serum from yellow fever vaccine production. The case demonstrated that vaccines can transmit bloodborne pathogens and led to safer vaccine manufacturing practices. The incident also contributed to the understanding of hepatitis B as a distinct disease entity, advancing virology research.