14 Jun 2016

Infants under 9 months of age

The risk of yellow fever vaccine-associated encephalitis is higher in infants under nine months of age Infants under 9 months of age
Image provided by NHS Photo Library


The risk of yellow fever (YF) vaccine-associated encephalitis is higher in infants under nine months of age [1]. The risk is inversely proportional to age (highest risk for the youngest infants) [1-3]. During the 1950’s, when there was no age restriction on the use of the YF vaccine, 15 cases of encephalitis were reported in infants. Of the 15 cases, 13 (87%) occurred in infants under four months of age and all were under seven months of age (age was not documented in the remaining two cases) [2]. The vaccine should therefore never be administered to infants under six months of age [1, 2].

Infants aged six to nine months should only be immunised if the risk of YF during travel is unavoidable; expert opinion should be sought in these situations [1]. For this age group, vaccination is usually only recommended during epidemics / outbreaks when the risk of YF virus transmission may be very high [see TravelHealthPro Country Information Pages].

Individual itineraries should be considered on a case by case basis, and if possible, travel should be delayed until the infant is 9 months of age [2].  

When travel is unavoidable, and YF vaccine is not an option, particular care with insect bite avoidance day and night should be recommended.  

Very young children (aged less than 2 years) may have suboptimal sero-conversion rates following a single dose of the vaccine and may, therefore, benefit from a single booster dose 10 years after the original dose [1, 4].

Febrile illness

General vaccine guidance from Public Health England states that minor illnesses without fever or systemic upset are not valid reasons to postpone immu Read more

Pre-conception, pregnant women and breastfeeding

Each situation should be evaluated on a case by case basis, a comprehensive risk assessment should be performed, and women should be encouraged to mak Read more

Individuals aged 60 years and older

Age alone is not considered a contraindication to YF vaccination, and vaccination can be given to those aged 60 years and older following risk assessm Read more

Off-site administration

Off-site administration policy for designated Yellow Fever Vaccination Centres (YFVCs) in England, Wales and Northern Ireland Read more
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