Yellow fever (YF) is a vaccine-preventable viral infection transmitted predominantly by certain species of day biting mosquitoes. YF virus can cause an illness that results in jaundice (yellowing of the skin and eyes) and bleeding, with severe damage to the major organs. The death rate is high in those who develop severe disease.
YF is a risk in tropical parts of Africa, South America, eastern Panama in Central America and Trinidad in the Caribbean. Areas with a risk of YF transmission are countries (or areas within countries) where mosquito species known to transmit the disease are present and where the infection is reported in monkeys and/or humans.
Yellow fever is rare in western travellers. The last reported case in the UK was acquired by a laboratory technician working with the virus in London in the 1930s. There were six recorded deaths from YF in non-vaccinated European and American travellers between 1996 and 2010.
The risk of contracting YF is determined by the following factors:
- Travel destination.
- Intensity of YF transmission in the area to be visited.
- Season of travel (most cases in travellers have occurred in the late rainy season to early dry season).
- Duration of travel.
- Activities allowing exposure to mosquitoes.
- Immunisation status.
In order to prevent the international spread of YF, under International Health Regulations, countries may require proof of vaccination, recorded in an International Certificate of Vaccination or Prophylaxis (ICVP).
A highly effective live YF vaccine is available and in general vaccination is recommended for all persons visiting countries where there is a risk of YF virus transmission. Very rarely yellow fever vaccination is associated with serious adverse reactions. Prior to vaccination a careful risk assessment is required that takes into account:
- risk of disease to the individual
- certificate requirements for vaccination according to international health regulations
- risk of complications following vaccination
YF vaccine should not be given to the following:
- Infants less than six months.
- Persons with a confirmed anaphylactic reaction to a previous dose of YF vaccine.
- Persons with a confirmed anaphylactic reaction to any of the components of the vaccine.
- Persons with a confirmed anaphylactic reaction to egg.
- Persons who are immunocompromised due to a congenital condition, disease process or treatment.
- Persons with a history of a thymus disorder.
For those with a febrile illness (fever) or who are acutely unwell, YF vaccination should be postponed until full recovery.
Where travel to YF risk areas is unavoidable, YF vaccination may be considered for the following groups (expert opinion may be advisable):
- Breastfeeding women
- Infants aged six to eight months
- Individuals aged 60 years and older
- HIV-infected individuals (with a CD4 count greater than 200 and a suppressed viral load, specialist advice should be sought)
- Pregnant women
Length of protection
Current Stamaril prescribing information states that revaccination is recommended every 10 years for those at risk and current International Health Regulations (2005) require revaccination at 10-year intervals if indicated, in order to retain a valid ICVP. However, with some exceptions, protection from YF vaccination lasts for at least 35 years, and could be lifelong. Some countries have reflected this in their certificate requirement for YF.
A booster dose should be offered to those needing a valid ICVP and a small subset of travellers who may be at continued risk.
FACT SHEET WRITTEN BY:
The National Travel Health Network and Centre (NaTHNaC) is commissioned by Public Health England to provide health information for both healthcare professionals and travellers. Information is compiled by the NaTHNaC clinical and scientific team, and updated regularly. Further advice on health risks and disease outbreaks is available at www.travelhealthpro.org.Date last reviewed: November 2015