• What is yellow fever?
• What is the risk of contracting the fever?
• What is the vaccination?
• Who should consider the vaccine?
• Who should not consider the vaccine?
• What are the risks and side effects?
• When should the vaccine be administered?
• How do I reduce the chances of contracting the disease?

Yellow fever is an acute flaviviral infection that is transmitted to humans by infected mosquitoes in tropical Africa and South America (it does not occur in Asia) and it is believed that the incidence of yellow fever is greatly underreported among local populations.

The symptoms of the first stage of the disease appear 3 to 6 days after exposure and include fever, nausea, vomiting, flushed face, constipation, stomach discomfort, headache, muscle pains (especially in the neck, back and legs), restlessness, and irritability, which may progress to haemorrhage and jaundice.

In severe cases, the fever drops at around 2 to 5 days after onset, and a remission of several hours or days follows. The fever recurs, but the pulse remains slow, and the patient develops the classic symptoms of yellow fever, including jaundice (yellowed skin and eyes) and black, coffee-ground type vomit. 

The yellow fever vaccine is an attenuated, live-virus preparation of the 17D strain of yellow fever virus grown in leucosis-free chick embryos.

Each 0.5 ml dose contains not less than 1000 mouse LD50 units. The vaccine contains not more than 2 iu of Neomycin and 51u of Polymixin.

A single dose correctly given confers immunity in 100% of recipients; immunity persists for at least 10 years and probably for life, although re-immunisation is currently recommended after 10 years.

Yellow fever vaccine, in the UK, is given only at  centres designated by the UK Health Department. Our Preston  medical centre is a designated UK yellow fever centre. Yellow fever vaccination costs are not covered by the State National Health Service and have to be paid by the individual recipient. We stock and administer Stamaril yellow fever vaccine manufactured by Aventis Pasteur MSD.

 Our charge for booking appointments, medical assessment and advice by a fully-qualified UK trained doctor, vaccine administration and international yellow fever vaccine certification is £40 per individual. We comply fully with storage, immunisation procedure and vaccine disposal container requirements. Vaccine we administer is always used within 2 hours of reconstitution and is always newly-supplied vaccine from Evans Vaccines.

When required for entry by a country, a record of your immunisation must be entered and validated in the specific section of the yellow International Certificate of Vaccination, and it is valid for 10 years. In order to satisfy a country’s entry requirement, you must receive yellow fever immunisation no less than 10 days and no more than 10 years prior to entry. In the United Kingdom, immunisation is available only at centres designated by the NHS.

There are different types of yellow fever entry requirements. While many countries have no requirements, others may require an International Certificate of Vaccination from travellers arriving from 1 or more of the following:

• all countries
• countries or areas that lie in the so-called endemic zone
• infected countries
• infected areas
• countries that are maintained on a list and regarded as infected (although some may not actually be infected, nor even lie in the endemic zone)

Yellow fever requirements that target travellers coming from infected areas (as opposed to infected countries) can be particularly troublesome. Local health and customs officials in developing countries may have inaccurate or outdated information regarding areas of yellow fever infection in other countries and, consequently, may require proof of vaccination from all travellers arriving from infected countries. If you are caught in this situation and local health authorities attempt to administer the vaccine using potentially contaminated needles or syringes, you should make every possible protest against administration of the vaccine.

One way to avoid such situations is to get the vaccine and have it documented in your International Certificate of Vaccination if you are travelling from a country with areas of yellow fever infection to one with a requirement, even though it may not technically be required. In most such cases, it is also a good way to protect against illness.

Because the disease risk is high and the vaccine is very safe, WHO recommends this immunisation for travel outside the urban areas of countries where yellow fever risk exists, even if these countries do not officially report cases of the disease and do not require evidence of immunisation on entry.

Children younger than 4 months of age, people who have had a previous severe reaction to the vaccine and those who are extremely allergic to eggs should not receive this vaccine. Infants aged 4 to 8 months should only receive the vaccine under unavoidable, high-risk circumstances.

People with AIDS or some other suppression of the immune system should discuss the risks and benefits of this vaccine carefully with their health care provider.

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.)

Persons who have a moderate illness (with or without a fever) should postpone receiving this vaccine until they are well.

If the vaccine may be required and a physician thinks that it should not be administered for medical reasons, you should get a signed, dated statement of the reasons on the physician’s letterhead stationery, and the physician should make a corresponding entry in your International Certificate of Vaccination. But before departure, you should check with the embassy of the country you will be visiting to ensure that a medical exemption will be accepted.

Reactions to this vaccine are generally mild and include fever, headache, and muscle ache. These reactions occur 5 to 14 days after immunisation. Serious side effects are rare.

In our practice, with these carefully selected vaccines we have never yet seen a significant adverse reaction in over 10 years of use. We do however stock full anaphylaxis treatments and carefully screen potential vaccine recipients for allergic and general health problems.

The vaccine is delivered subcutaneously, requiring the smallest UK gauge needle and the 0.5 ml dose is the same volume as the first infant  vaccination schedule in the UK.

The very occasional adverse effects we do have reported to us (we encourage patients to inform us of any problems through our 24 hour switchboard) are short-lived aching in the vaccination site and a short-lived flu-like illness between days 4 to 10 after vaccination. One patient recently, who had a particular needle-phobia, despite our assurances, felt unwell immediately after the vaccination. She remained however haemodynamically stable and after a short rest recovered fully (ever without a cup of English tea!).

This vaccine is given as a single injection given subcutaneously. If a country requires the vaccine for entry, travellers must allow at least 10 days before entering the country for vaccination. Also, if other live-virus vaccines are necessary for travel (for example polio), they should be completed on the same day as the yellow fever vaccination. Otherwise, travellers may have to allow up to 3 weeks before travel for administration of all live-virus vaccines. 

Every traveller’s first line of defence is to take personal protective measures against mosquitoes as there may also be a risk of contracting other mosquito-borne illnesses, such as malaria.

You should wear mosquito repellent clothing containing DEET (30% concentration is generally adequate), and stay in air-conditioned or well-screened rooms. Reduce your amount of skin exposure when outdoors by wearing socks, long pants and long-sleeved shirts - particularly in the evenings (only Canadian mosquitoes appear to attack 24 hours a day!). If you use a repellent containing DEET on children, do so with care – there is some evidence of a potential for neurological side effects associated with overdoses.

If you will be travelling in rural areas, carry along a portable bednet, which you can buy at backpacking and army-navy surplus stores, and aerosol room insecticides to kill indoor mosquitoes. You can apply permethrin (a mosquito repellent/insecticide) to clothing and mosquito netting.

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