Yellow Fever is a serious acute viral infection spread via the bite of an infected mosquito. It is found mainly in tropical Africa and South America and does not occur in Asia. It is more common in rural areas where monkeys act as a reservoir of viral infection. The incubation period of infection is short, 3-6 days and there then follows a non-specific acute viral illness before full recovery ensues for most. Around 15% with acute infection progress to a severe toxic phase with fever, jaundice, haemorrhages and deteriorating kidney function. There is no specific anti-viral treatment and mortality in this group is high – up to 60%.
Protection begins with avoidance of mosquito bites in risk areas remembering that the mosquito transmitting yellow fever bites in the daytime also. A highly effective live virus vaccine is available. Immunity following a single dose may be life-long and develops rapidly, within 10 days. Booster vaccination may be required for international certification purposes. The yellow fever certificate is provided following vaccination and is valid 10 days following vaccination and for 10 years thereafter. Always carry the original certificate with your travel papers, a photocopy will not suffice. A permanent record of vaccination is held by the clinic and duplicate certificates can be issued in the event of loss.
Definite contraindications to vaccination are as follows; immunosuppression from disease or treatments - for example oral steroids or chemotherapy, thymus dysfunction or removal, age < 6 months, acute severe febrile illness, hypersensitivity to previous yellow fever vaccination, eggs or chicken protein, symptomatic HIV infection or associated impaired immune function. When required an exemption certificate to vaccination on medical grounds can be provided by the clinic. Finally, particular caution is required in use of the vaccine in specific groups; babies 6-9 months, during pregnancy, breast feeding and in travellers age over 60 years.
Of those vaccinated, mild local effects (pain, tenderness, and swelling) may develop at the site of the vaccination. Mild general upset such as lethargy, feverishness and aching may occur. Incidence of local and mild general side effects is 5-10% and usually onset is within a few days following vaccination. Symptoms usually settle quickly and can be treated with paracetomol. There have been reports of very occasional serious general reactions occurring up to 1 month following vaccination (of the order 1 per 400,000) with symptoms affecting vital organs or nervous tissue. This highlights the importance of ensuring vaccination is received only by travellers to yellow fever risk areas following a full appropriate risk assessment. The patient information leaflet provided with Stamaril vaccine should be retained for reference following vaccination.
Stamaril yellow fever vaccine is a live vaccine preparation and can be given on the same day as chickenpox vaccine (also a live vaccine) otherwise a minimum four weeks interval should be observed, and with MMR vaccine, to achieve a full response to both MMR and yellow fever vaccinations a four weeks minimum interval is necessary. Timing of non-live vaccines, for example hepatitis and typhoid or tetanus to yellow fever vaccination administration is unrestricted.