Yellow Fever Vaccine
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Yellow Fever Vaccine

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What Is Yellow Fever?

Yellow fever is a virus transmitted to humans through mosquito bites.

Jungle yellow fever is transmitted to humans through mosquitoes who have been infected by monkeys who carry the virus.

Urban yellow fever is passed to mosquitoes from infected humans, and the mosquitoes continue to infect other humans by biting them. Yellow fever cannot be passed from human to human.

The yellow fever virus is found only in South America and sub-Saharan Africa, and jungle yellow fever is typically only passed to humans who work in the rain forest. Yellow fever can only be contracted through a bite from a female mosquito.

Risk factors for getting yellow fever include traveling to an area where humans are already infected by the yellow fever virus, or where there are contaminated monkeys or mosquitoes that can transmit the virus.

Symptoms for yellow fever include:

  • High fever
  • Chills and muscle aches
  • Vomiting, sometimes vomiting blood
  • Headache
  • Backache

More serious complications include:

Symptoms typically begin 3-6 days after infection. Yellow fever is diagnosed with a blood test, but there is no course of treatment for the virus. Doctors usually recommend a long period of bed rest, along with plenty of fluids. Patients should also avoid places where mosquitoes are present to avoid spreading the disease to others.

Illness from yellow fever varies from a self-limited illness to hemorrhagic fever, which can be very severe and can lead to death.

What Is the Yellow Fever Vaccine?

The vaccine is a weakened, live form of the yellow fever virus. The vaccine is created by growing the live virus in the lab. The preferred storage method is frozen vials. The vaccine is administered subcutaneously (beneath the skin).

The yellow fever vaccine is not usually given with other vaccines, but it may be given with the hepatitis B vaccine.

Who Should Get Vaccinated and When?

The following individuals should get vaccinated:

  • All individuals aged 9 months and older who are traveling to places where yellow fever is present, generally South America and Africa
  • Travelers should be vaccinated at least 10 days before departure
  • All residents of areas where yellow fever is present

The vaccine lasts for 10 years. Every 10 years, a booster is required if you are at risk for contracting yellow fever.

What Are the Risks Associated With Yellow Fever Vaccine?

Common minor side effects include:

  • Fever
  • Soreness, swelling, or redness sat the injection site
  • Muscle aches

Rare, serious side effects include:

  • Nervous system reaction
  • Severe allergic reaction
  • Organ failure

Who Should Not Get Vaccinated?

Infants under 9 months of age should not received this vaccine. If your baby is 6-8 months of age and he or she must travel to an area where there are cases of yellow fever, talk to your baby's doctor about vaccination. Infants younger than 6 months should not get vaccinated.

In addition, the following people should not get vaccinated. Those who:

  • Are allergic to eggs, chicken, or gelatin
  • Have a disease that weakens the immune system, such as HIV or AIDS
  • Are receiving treatments that weaken the immune system, such as cancer treatment
  • Have cancer
  • Have problems with the thymus
  • Are pregnant (theoretical risk to the developing fetus)

What Other Ways Can Yellow Fever Be Prevented Besides Vaccination?

To decrease you chance of getting yellow fever, do the following:

  • Use insect repellent.
  • Wear long-sleeved shirts and long pants.
  • Stay in screened areas.

What Happens in the Event of an Outbreak?

An outbreak of yellow fever in the United States is highly unlikely, as the virus is not geographically present. But in the event of an outbreak, uninfected individuals would be vaccinated and precautions would be taken to reduce transmission.


National Library of Medicine

Vaccine and Immunizations
Centers for Disease Control and Prevention


Children’s Hospital of Philadelphia, Vaccine Information Center website. Available at: Accessed February 4, 2007.

The Directors of Health Promotion and Education website. Available at: Accessed February 4, 2007.

US Department of Health and Human Services, National Immunization Program website. Available at: Accessed March 3, 2008.

Last reviewed February 2008 by David Horn, MD, FACP

Please be aware that this information is provided to supplement the care provided by your physician. It is neither intended nor implied to be a substitute for professional medical advice. CALL YOUR HEALTHCARE PROVIDER IMMEDIATELY IF YOU THINK YOU MAY HAVE A MEDICAL EMERGENCY. Always seek the advice of your physician or other qualified health provider prior to starting any new treatment or with any questions you may have regarding a medical condition.

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