The yellow fever vaccine is a live vaccine, meaning it contains a weakened form of the virus. For most people, a single yellow fever vaccine can provide lifelong protection against the virus.

Yellow fever is a viral hemorrhagic condition that can cause a high fever and organ damage. However, a safe, effective, and affordable vaccine exists that can provide immunity and lifelong protection against the disease.

Health experts recommend the vaccine for those aged 9 months or older. It is particularly advisable for people traveling to or living in at-risk areas, such as Africa and South America, to get the vaccine. Some countries may require proof of vaccination for entry.

Anyone who has concerns or is unsure whether they require the vaccine should discuss this with their doctor.

In this article, we will discuss the safety and efficacy of the yellow fever vaccine and who should get it.

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Yellow fever is a viral infection that may cause symptoms such as fever, aches and pains, and organ damage. In some cases, the infection may damage the liver and cause a person to develop jaundice, hence the name “yellow fever.”

The yellow fever virus belongs to the Flaviviridae family of viruses. Transmission typically occurs through the bite of an infected Aedes or Haemagogus mosquito. Exposure to the virus is more likely to occur in certain areas of Africa and South America.

The World Health Organization (WHO) estimates that in 2013, there were 84,000–170,000 severe cases of yellow fever and 29,000–60,000 fatalities.

The Centers for Disease Control and Prevention (CDC) note that the majority of people with yellow fever infections will either have no symptoms or mild symptoms. A small number of people who become infected will have severe symptoms, which can cause death in 30–60% of these cases.

The yellow fever vaccine is a single-dose vaccine that can provide lifelong protection for most people. It is a live-attenuated vaccine. This means that the vaccine uses a weakened, or attenuated, form of the yellow fever virus. As this type of vaccine is so similar to the natural infection, the body can create a strong and long lasting immune response from just one dose without the need for a booster shot.

The yellow fever vaccine is a safe way to protect against yellow fever infections. Adverse reactions or serious events from the vaccine itself are very rare.

The WHO notes that severe adverse events following immunization, such as the vaccine promoting an attack on the liver or kidneys, occur in about 0.09–0.4 cases per 10,000 doses in populations that do not usually have exposure to the virus, such as the United States.

The yellow fever vaccine is highly effective. The WHO states that the vaccine provides immunity within 10 days for 80–100% of people. Within 30 days, more than 99% of vaccinated people are immune.

The yellow fever vaccine provides lasting protection from yellow fever infections. The CDC says that a single dose of the vaccine provides lifelong protection from the virus.

There is no need for a booster shot. However, the CDC notes that some travelers may consider getting a booster if it has been 10 years since their vaccination and they plan to travel to an area with an ongoing outbreak.

Experts recommend the yellow fever vaccine for people who are 9 months or older. For some people, this may only be necessary if they are likely to be at risk of a yellow fever infection. In most cases, this means living in or traveling to a country where the virus is endemic or occurs at higher rates. These countries generally have requirements to vaccinate before entry, providing plenty of notice to get the vaccine.

Other people likely to require the vaccine include laboratory personnel or healthcare workers who may encounter the virus through their work.

Those visiting countries where yellow fever is endemic, including some areas in South America and Africa, will need to get the vaccine at least 10 days before traveling.

Some travel agencies or airlines may warn people that they will need proof of vaccination before traveling to these countries. However, it is still important to research the exact location and find out whether vaccination is required before travel.

Otherwise, most people are able to receive the vaccine from 9 months of age.

Some groups may have a higher risk of reactions from the vaccine but may still benefit from it.

These groups include:

  • people over the age of 60 years
  • children aged 6–8 months
  • those who are pregnant or breastfeeding

People in these groups, or their parents or caregivers, should discuss their options with a doctor before getting the vaccine.

It may not be advisable for some people to get the vaccine. These individuals include:

  • infants under the age of 6 months
  • people with severe immunodeficiency from another condition, such as a thymus disorder
  • those using immunosuppressant drugs
  • people severely allergic to egg protein
  • people severely allergic to other vaccine ingredients
  • organ donor recipients
  • people with a malignant tumor
  • those showing symptoms of an active HIV infection
  • those with primary immunodeficiency

People who cannot get the yellow fever vaccine may experience some limitations to travel and may not be able to visit countries where the fever is endemic.

Side effects and reactions to the yellow fever vaccine are generally mild. Side effects may include:

  • soreness, discoloration, or swelling at the injection site
  • headache
  • muscle aches
  • fatigue
  • low grade fever

Rarely, more serious reactions are possible, some of which can be life threatening. Severe reactions may include:

  • allergic reactions and anaphylaxis, which may include difficulty breathing or swallowing and shock
  • Guillain-Barré syndrome, a condition of the nervous system causing the immune system to damage nerve cells
  • swelling of the brain or spinal cord
  • damage to internal organs, such as the liver or kidneys

The risk of adverse reactions may be higher in certain groups, such as people over the age of 60 years and those with severe immunodeficiency. The CDC states that many pregnant women receive the yellow fever vaccine without any adverse effects. However, because it is a live vaccine, it still poses a possible risk to the fetus.

Yellow fever vaccination only occurs at specific vaccination centers. The CDC offers a yellow fever vaccination clinic search tool to help find a designated vaccine center.

It is important to get the vaccine from these centers, as they will provide an international certificate of vaccination or prophylaxis (ICVP), which the person will need to travel to countries with these limitations.

The cost of vaccination can vary depending on the center. Some insurance options may help reduce the cost, as well.

The yellow fever vaccine is a single-shot vaccine that provides lifetime protection from yellow fever for most people. It may only be necessary for people traveling to countries where the risk of yellow fever is high. People will need to get a vaccine from a designated center to receive certification of the vaccine before they travel.

Some people should not get the vaccine or may be more at risk of reactions. These individuals should talk with their doctor to discuss all of the options.