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Information on Yellow Fever


Yellow fever is a viral disease that is transmitted to humans by mosquitoes. The major areas of risk for yellow fever are sub-Saharan Africa and the Amazon areas of South America. Yellow fever leads to a severe multi system disease including brain and liver involvement and can be fatal. There is no specific treatment for it, but it is preventable through the use of yellow fever vaccine, which is nearly 100% effective.
yellow fever map


Whether you receive the vaccine or not, you should take personal protective measures against mosquitoes. Depending on your itinerary, there may be a risk of contracting other mosquito-borne illnesses, in addition to yellow fever.

You should wear mosquito repellent containing DEET (preferably an extended release formula), and stay in well-screened rooms. Reduce your amount of skin exposure when outdoors by wearing socks, long pants, and long-sleeved shirts. If you use a repellent containing DEET on children, do so with care –avoid contact with the mouth and restricting it to low levels of DEET (10%).

If you will be traveling in rural areas, carry along a portable bednetting and aerosol room insecticides to kill indoor mosquitoes. Apply permethrin (a mosquito repellent/insecticide) to clothing and mosquito netting greatly improves their protective effect.


Yellow fever vaccine is an attenuated (weakened), live-virus vaccine that is prepared in eggs. It is nearly 100% effective in preventing yellow fever. In Canada, immunization is available only at centers designated by Health Canada.

Entry Requirements

There are different types of yellow fever entry requirements. Some countries require proof of vaccination for all arriving travelers; other countries may require it only if you came from or traveled through ( in the last 6 months) a country (including airport transit) that has a risk of yellow fever infection. Some countries have no requirements, but you may still need to receive the vaccine to protect yourself from disease.

For countries that require yellow fever vaccination, you need to have proof of your immunization. This information must be recorded and validated in the "International Certificate of Vaccination," which is then valid for 10 years. You must have received the yellow fever immunization at least 10 days but not more than 10 years prior to entering the country.

Local health and customs officials in some developing countries may require proof of vaccination even when it is not needed. In this case, the local authorities may try to administer yellow fever vaccine to you before allowing you to enter the country. If you find yourself in this situation, you should make every possible protest against receiving the vaccine in this manner, because you risk being vaccinated with contaminated needles or syringes.

In the event that you cannot receive yellow fever vaccine due to medical reasons, we will provide you with an "Exemption Letter," a signed, dated statement of the reasons you cannot be immunized. Before departure, you should check with the embassy of the country you will be visiting to ensure that a medical exemption will be accepted.

Contraindication to vaccination

People who have had a previous severe reaction to the vaccine, or persons who are extremely allergic to eggs.


In children younger than 9 months of age.

Infants aged 6 to 8 months should receive the vaccine only if they will be unavoidably exposed to an area of risk for yellow fever.

Children < 4 months of age should never receive this vaccine.

People with AIDS or some other suppression of the immune system should discuss the risks and benefits of this vaccine carefully with our clinic staff.

The only circumstance under which this vaccine should be administered during pregnancy is when the journey is necessary and the risk of contracting the disease is substantial. (The vaccine may be given to nursing mothers.)

Adverse Effects

Reactions to this vaccine are generally mild and include fever, headache, and muscle ache. These reactions occur 5 to 14 days after immunization.

Serious side effects and even death following vaccination are rare and are usually seen in the elderly or in the immuno-compromised.


Yellow fever vaccine is given as a single injection.

If a country requires the vaccine for entry, travelers must receive the vaccine at least 10 days before entering the country.

If other live-virus vaccines (such as measles, oral typhoid, or chicken pox) are necessary for travel, they should be completed on the same day as the yellow fever vaccination if possible. Otherwise, travelers may have to allow up to 4-8 weeks before travel for administration of all live-virus vaccines.

A booster dose is needed every 10 years for purposes of fulfilling entry requirements. For personal protection, however, studies have indicated that yellow fever immunity (after 1 dose of vaccine) can persist for 30-35 years and perhaps for life.

Vaccine Prices

Click here to see our Yellow Fever vaccination prices.