What is Yellow Fever Vaccine: Uses, Dosage, Side Effects and More

The yellow fever vaccine is a live, weakened virus vaccine that protects you from yellow fever, a serious mosquito-borne disease found in parts of Africa and South America. This single-dose vaccine provides long-lasting immunity and is often required for international travel to certain countries.

Yellow fever can cause severe illness including liver damage, bleeding, and even death. The vaccine has been safely protecting travelers and people living in at-risk areas for decades, making it one of our most effective tools against this potentially deadly disease.

What is Yellow Fever Vaccine?

The yellow fever vaccine contains a live but weakened version of the yellow fever virus that cannot cause the actual disease in healthy people. When injected under your skin, it teaches your immune system to recognize and fight the real yellow fever virus if you're ever exposed to it.

This vaccine is given as a subcutaneous injection, meaning it goes into the fatty tissue just under your skin rather than deep into muscle. The weakened virus in the vaccine multiplies just enough to create strong, long-lasting immunity without making you sick.

Healthcare providers have been using this vaccine successfully since the 1930s. It's considered one of the most effective vaccines available, with a single dose providing protection that can last a lifetime for most people.

What is Yellow Fever Vaccine Used For?

The yellow fever vaccine prevents yellow fever infection, a viral disease spread by infected mosquitoes in tropical regions of Africa and South America. You might need this vaccine if you're traveling to countries where yellow fever is present or if you live in an area where the disease occurs.

Many countries require proof of yellow fever vaccination before allowing entry, especially if you're traveling from a country where the disease is found. This requirement helps prevent the spread of yellow fever to new areas where the right type of mosquitoes exist but the disease hasn't been seen before.

The vaccine is also recommended for laboratory workers who might handle the yellow fever virus and for people living in areas where yellow fever outbreaks occur. Some countries may require the vaccine even for brief airport stopovers in affected regions.

How Does Yellow Fever Vaccine Work?

The yellow fever vaccine works by introducing a weakened version of the yellow fever virus into your body, which cannot cause the actual disease but can trigger your immune system to build protection. This is considered a strong and highly effective vaccine that creates robust immunity.

Once you receive the vaccine, your immune system recognizes the weakened virus as foreign and creates antibodies specifically designed to fight yellow fever. Your body also develops memory cells that remember how to quickly produce these antibodies if you encounter the real virus later.

This immune response typically develops within 10 days of vaccination and provides protection for at least 10 years, though many experts believe it may last a lifetime. The vaccine creates such strong immunity that most people only need one dose in their entire lifetime.

How Should I Take Yellow Fever Vaccine?

The yellow fever vaccine is given as a single injection under the skin, usually in your upper arm. You should receive this vaccine at least 10 days before traveling to an area where yellow fever is present, as it takes this long for your body to develop full protection.

You don't need to take any special precautions with food or drink before or after receiving the vaccine. However, it's helpful to be well-hydrated and have eaten recently to prevent feeling faint during the injection process.

The vaccine must be given at an approved yellow fever vaccination center by trained healthcare providers. These centers have special requirements for storing and handling the vaccine to ensure it remains effective. You'll receive an International Certificate of Vaccination that serves as proof of your vaccination for travel purposes.

How Long Should I Take Yellow Fever Vaccine For?

The yellow fever vaccine is typically a one-time vaccination that provides long-lasting protection. Most people only need a single dose in their lifetime, as the immunity it creates is very strong and durable.

The World Health Organization changed its recommendations in 2014, stating that one dose provides lifelong protection for most people. Previously, a booster shot was recommended every 10 years, but research showed this wasn't necessary for most individuals.

However, some people may need a booster dose after 10 years if they have certain risk factors or weakened immune systems. Your healthcare provider can help determine if you need additional doses based on your individual health situation and travel plans.

What Are the Side Effects of Yellow Fever Vaccine?

Most people experience mild side effects from the yellow fever vaccine, if any at all. The most common reactions are similar to what you might feel with other vaccines and typically resolve within a few days.

Here are the side effects you might experience, starting with the most common ones:

• Soreness, redness, or swelling at the injection site
• Low-grade fever
• Mild headache
• Muscle aches
• Fatigue or feeling generally unwell
• Mild nausea

These common side effects usually appear within a few days of vaccination and go away on their own. Taking over-the-counter pain relievers and applying a cool compress to the injection site can help with any discomfort.

Serious side effects are rare but can occur. These more concerning reactions require immediate medical attention:

• Severe allergic reaction (difficulty breathing, swelling of face or throat, widespread rash)
• Yellow fever vaccine-associated neurologic disease (brain inflammation, which is extremely rare)
• Yellow fever vaccine-associated viscerotropic disease (organ failure, also extremely rare)
• High fever lasting more than a few days
• Severe headache with neck stiffness

These serious reactions are very uncommon, occurring in less than 1 in 100,000 people vaccinated. However, knowing the signs helps you seek prompt medical care if needed.

Who Should Not Take Yellow Fever Vaccine?

Certain people should avoid the yellow fever vaccine because they have a higher risk of serious side effects. The vaccine contains live virus, so it's not safe for everyone, particularly those with weakened immune systems.

You should not receive the yellow fever vaccine if you have any of these conditions:

• Severe illness with fever at the time of vaccination
• Severe allergic reaction to previous yellow fever vaccine or any vaccine component
• Weakened immune system due to HIV/AIDS, cancer treatment, or immunosuppressive medications
• Thymus gland disorders
• Primary immunodeficiency conditions

Special consideration is needed for certain groups who may have increased risks:

• Adults over 60 years old (higher risk of serious side effects)
• Pregnant women (unless travel to high-risk areas is unavoidable)
• Breastfeeding mothers
• Infants under 9 months old
• People with egg allergies (the vaccine is grown in eggs)

If you fall into any of these categories, discuss the risks and benefits with your healthcare provider. Sometimes the risk of yellow fever infection outweighs the vaccine risks, especially if you must travel to high-risk areas.

Yellow Fever Vaccine Brand Names

The yellow fever vaccine is available under the brand name YF-VAX in the United States. This is currently the only yellow fever vaccine approved and available in the U.S.

YF-VAX is manufactured by Sanofi Pasteur and contains the 17D-204 strain of yellow fever virus. This is the same strain that has been used safely in yellow fever vaccines worldwide for many decades.

In other countries, you might encounter different brand names for yellow fever vaccines, but they all contain the same basic 17D strain of weakened yellow fever virus. All approved yellow fever vaccines provide equivalent protection against the disease.

Yellow Fever Vaccine Alternatives

There are no alternative vaccines for yellow fever prevention. The live, weakened virus vaccine is the only vaccine available to protect against yellow fever infection.

If you cannot receive the yellow fever vaccine due to medical reasons, your only options for protection are avoiding areas where yellow fever is present or taking strict precautions against mosquito bites. These precautions include using insect repellent, wearing long-sleeved clothing, and staying in air-conditioned or screened areas.

Some countries may accept a medical waiver letter from your doctor if you cannot receive the vaccine for health reasons. However, this doesn't protect you from getting yellow fever, so avoiding travel to affected areas is the safest option if you cannot be vaccinated.

Is Yellow Fever Vaccine Better Than Other Travel Vaccines?

The yellow fever vaccine is uniquely important because it's the only way to prevent yellow fever, and many countries legally require it for entry. Unlike some other travel vaccines that prevent diseases with available treatments, yellow fever has no specific treatment once you're infected.

Compared to other travel vaccines, the yellow fever vaccine provides exceptionally long-lasting immunity. While vaccines like typhoid or hepatitis A may need boosters every few years, yellow fever vaccination typically lasts a lifetime.

The yellow fever vaccine also serves a dual purpose - it protects your health and meets international travel requirements. This makes it more essential than optional travel vaccines when visiting affected areas. However, it's not necessarily "better" than other vaccines, just different in its requirements and duration of protection.