Yellow fever vaccine
The yellow fever vaccine is a crucial preventive measure against yellow fever, an acute infectious disease transmitted by mosquitoes and caused by a flavivirus. This disease is endemic to parts of South America and Africa, with an estimated risk of contracting it at about 1 in 267 in these regions, leading to a mortality rate of 20 to 50 percent among those infected. Developed by virologist Max Theiler in 1937, the vaccine uses a live but weakened strain of the virus and has been administered in over four hundred million doses globally. One dose typically provides lifelong immunity, although some countries recommend a booster.
Travelers to endemic areas and individuals routinely exposed to the virus, such as researchers, are advised to get vaccinated, while it is not recommended for newborns under nine months or for pregnant women in their first trimester. Effective protection begins ten days post-vaccination, and proof of vaccination is often required for entry into certain countries. The vaccine is generally safe, with common side effects including localized soreness, mild fever, and fatigue occurring within a week of administration. Overall, the yellow fever vaccine is vital for public health, particularly in regions where the disease is prevalent.
Subject Terms
Yellow fever vaccine
Definition
The yellow fever vaccine was developed to fight yellow fever, which is an acute infectious disease transmitted by mosquitoes and caused by a flavivirus. Yellow fever remains endemic to parts of South America and in Africa. The reported risk of contracting yellow fever, when in an endemic area, is approximately 1 in 267; of those infected, between 20 and 50 percent will die. The degree of risk does vary depending on location, season, and specific circumstances. No antiviral treatment is effective against the yellow fever virus, so a vaccine was developed to prevent people from contracting the disease. The vaccine is prepared from the 17D strain of the disease, which is live but attenuated (weaker). More than four hundred million doses of yellow fever vaccine have been administered worldwide. The yellow fever vaccine is highly effective with just one dose, although some countries recommend a booster dose.
History
As was first thought, yellow fever was conclusively identified as a virus rather than bacteria in 1928. Max Theiler, a South African-born virologist at New York’s Rockefeller Foundation, developed the yellow fever vaccine in 1937. He initially passed the virus through laboratory mice and found that the weakened form of the virus provided immunity to Rhesus monkeys. During his work with the virus, Theiler contracted yellow fever but survived and consequently developed immunity. Theiler was awarded the Nobel Prize in Physiology or Medicine in 1951 for developing the yellow fever vaccine.
Administration
Persons traveling to or planning to live in areas where yellow fever is endemic should receive the vaccine. People routinely exposed to the yellow fever virus, such as researchers and laboratory staff, are also encouraged to receive the vaccine. The vaccine, however, is not recommended for newborns younger than nine months of age or women during their first trimester of pregnancy. A healthcare professional administers the yellow fever vaccine in a single injection. Effective protection from the virus begins after ten days, and protection generally lasts a lifetime.
Documentation
To legally enter some countries, people must carry internationally recognized proof of receiving the yellow fever vaccine. This proof is established with a stamped document, the International Certificate of Vaccination Against Yellow Fever.
Side Effects
The yellow fever vaccine is safe. As with any drug or vaccine, strict regulations are enforced during its development and manufacturing. Common physical reactions to the vaccine include soreness and tenderness or redness at the site of the injection. Also, a slight headache, low-grade fever, or aching muscles can occur five to ten days after receiving the vaccine. Additional side effects include fatigue, nausea, vomiting, swollen lymph nodes, rash, and loss of appetite.
Bibliography
Bloom, Barry R., and Paul-Henri Lambert, editors. The Vaccine Book. San Diego, Calif.: Academic Press, 2002.
Frierson, J. Gordon. "The Yellow Fever Vaccine: A History." Yale Journal of Biology and Medicine, vol. 83, no. 2, June 2010, pp. 77-85.
"Immunization, Vaccines and Biologicals." World Health Organization, www.who.int/teams/immunization-vaccines-and-biologicals/diseases/yellow-fever. Accessed 2 Oct. 2024.
Jong, Elaine C., and Russell McMullen, editors. Travel and Tropical Medicine Manual. 4th ed., Philadelphia: Saunders/Elsevier, 2008.
Norrby, Erling. "Yellow Fever and Max Theiler: The Only Nobel Prize for a Virus Vaccine." Journal of Experimental Medicine, vol. 204, no. 12, 26 Nov. 2007, pp.2779-2784.
"Yellow Fever Vaccine Information for Healthcare Providers." CDC, 23 Aug. 2024, www.cdc.gov/yellow-fever/hcp/vaccine/index.html. Accessed 2 Oct. 2024.