Travel health - yellow fever immunization

Yellow fever is a serious viral disease spread by mosquitoes, found in parts of Africa and Central and South America. The World Health Organization (WHO) keeps updated lists of countries where yellow fever occurs. The disease is named for the yellowing of the skin and eyes (jaundice) seen in serious infections, which is caused by the virus damaging the liver. Yellow fever can be fatal, and you should always protect yourself against mosquito bites.

Vaccination is generally safe and effective and reduces the risk of infection. Some countries require travellers passing through affected areas to show proof of vaccination, recorded on an International Certificate of Vaccination or Prophylaxis. Vaccination and certification are available through travel clinics or health providers authorised by the WHO. Fatal cases continue to be reported in unvaccinated travellers to Africa and South America.

Symptoms#

The first symptoms appear 3 to 6 days after exposure to the virus. This is known as stage one, and symptoms can include:

• Fever
• Nausea and vomiting
• Flushed face
• Constipation
• Stomach ache
• Headache
• Muscle pain
• Restlessness and irritability

These symptoms usually last 3 to 4 days and then settle over one to two days. In mild cases, the infection ends after stage one as the virus is cleared.

Severe disease#

In severe cases, the period of improvement is followed by more serious symptoms and complications, known as stage two. This happens in about 15 to 25% of cases, even when there has been a remission period, because the virus can infect organs such as the liver, heart and kidneys. This is also called the “toxic” stage, and about half of the people who reach it will die.

Severe complications can include:

• High fever
• Pain in the upper abdomen
• Vomiting, including black, “coffee-ground” vomit
• Bleeding
• Jaundice (yellow skin and eyes)
• Kidney failure
• Liver failure
• Death

Vaccination against yellow fever#

If you are travelling to or through areas where yellow fever occurs, some countries require you to be vaccinated. Your immunisation must be recorded and validated in an International Certificate of Vaccination or Prophylaxis by a healthcare provider authorised by the WHO.

Entry requirements vary by country. Some countries have no requirements, while others may require proof of vaccination from all travellers. Check the requirements for each country you plan to visit, or ask your doctor at your appointment.

It is best to see your doctor or a travel clinic 6 to 8 weeks before departure, in case a series of vaccines is needed. The yellow fever vaccine should be given at least 10 days before entering a country where it is a legal requirement, to avoid quarantine procedures. In most cases, once you have been vaccinated the certificate is valid for life.

People who should be vaccinated include:

• People over 9 months of age travelling to or living in areas with a high risk of yellow fever transmission
• People who work in laboratories and routinely work with the yellow fever virus

Speak with your doctor if you are pregnant and unable to avoid travel to an area where yellow fever occurs, as the vaccine is not usually recommended during pregnancy or breastfeeding.

Who should not receive the vaccine#

The vaccine may not be suitable for people who:

• Are under 9 months of age
• Have had a severe allergic reaction (anaphylaxis) to an earlier dose, or to any component of the vaccine
• Have allergies to eggs
• Have a weakened immune system due to illness or medical treatment
• Have a history of a thymus disorder – including myasthenia gravis, thymoma, thymectomy, DiGeorge syndrome, or damage to the thymus from chemotherapy or radiotherapy

Before you are vaccinated#

Tell your immunisation provider before the vaccine is given if you or your child:

• Is under 9 months of age
• Is pregnant or intends to become pregnant
• Is unwell (temperature over 38.5 °C / 101.3 °F)
• Has allergies to any other medications or substances
• Has had a serious reaction to any vaccine or to any vaccine component
• Has had a severe allergy to anything
• Has a disease or is having treatment that lowers immunity
• Is taking any prescription or over-the-counter medications

Side effects#

Immunisation against yellow fever is generally safe, although all medicines can have unwanted side effects. Side effects are uncommon and usually mild. For up to 5 to 10 days after vaccination they may include a low-grade fever (temperature), mild headache and muscle aches. Many vaccine injections can also cause soreness, redness, itching, swelling or a burning sensation at the injection site for one to two days.

To manage these effects:

• Drink extra fluids and avoid overdressing if there is a fever.
• Routine use of paracetamol after vaccination is not recommended, but if fever is present, paracetamol can be given. Check the label for the correct dose or ask your pharmacist, especially when giving paracetamol to children.

If a reaction is unexpected, persistent or severe, or if you are worried, see your doctor or immunisation provider as soon as possible, or go directly to a hospital. It is also important to seek advice if you or your child are unwell, as this may be due to another illness rather than the vaccine.

There is a very small risk of a serious allergic reaction (anaphylaxis) to any vaccine. This is why you are advised to stay at the clinic for at least 15 minutes after immunisation, in case further treatment is needed.

Two very rare side effects of the yellow fever vaccine are inflammation of the brain (meningoencephalitis) and organ failure (viscerotropic disease). People over 60 years of age are at a small risk of these rare side effects, and people with thymus disorders are at increased risk of viscerotropic disease. You can ask your immunisation provider how to report any significant adverse event following immunisation.

Immunisation and HALO#

The immunisations you may need depend on your health, age, lifestyle and occupation – together referred to as HALO. Talk to your doctor or immunisation provider if you think you or someone in your care has health, age, lifestyle or occupation factors that may make immunisation necessary.

Avoid mosquito bites#

Avoiding mosquito bites helps reduce the risk of yellow fever and other mosquito-borne diseases, whether or not you are vaccinated. A few simple measures help:

• Use an effective repellent on exposed skin that contains at least 30% DEET (N,N-Diethyl-meta-toluamide or diethyltoluamide) or 20% picaridin.
• Wear loose, light-coloured clothing that covers your skin, such as socks, long pants and long-sleeved shirts when outdoors.
• Use a bed net.
• Stay in air-conditioned, screened accommodation.
• Soak clothing, bedding, mosquito nets and tents in a safe repellent (such as permethrin) before travel.

If you become unwell while overseas, contact a local doctor or hospital – most accommodation providers and local health services can give you a list. If you do not speak the language, ask for someone who speaks English.

Key points#

• Vaccination against yellow fever is generally safe and effective and reduces the risk of infection.
• Avoid mosquito bites to reduce the risk of all mosquito-borne diseases.
• The first symptoms appear 3 to 6 days after exposure and include fever, restlessness and irritability.
• Stage-one symptoms usually last 3 to 4 days and then settle over one to two days.

Where to get help#