Mon, 05/25/2020 | News

Yellow fever vaccination in egg-allergic children

A new case series on yellow fever (YF) immunisation in egg-allergic children has proposed skin testing may not be required for children with mild (non-anaphylactic) egg allergy and that a 2-step graded challenge under medical supervision is a safe alternative. The case series, conducted by authors from the National Centre of Immunisation Research and Surveillance (NCIRS) in collaboration with the Royal Children's Hospital in Melbourne, has been published in the Paediatric Infectious Disease Journal.

Yellow fever (YF) vaccine is a live, freeze-dried preparation of attenuated 17D strain YF virus. The virus is cultured in, and harvested from, embryonated chicken eggs, similar to influenza vaccine. Egg anaphylaxis is no longer considered a contraindication to influenza vaccination; however, many immunisation guidelines state that egg anaphylaxis is a contraindication to YF vaccination. The US Advisory Committee on Immunization Practices recommends for egg-sensitive persons, a scratch test or intradermal test can be performed to check for reactivity before giving the vaccine. The Australian Immunisation Handbook recommends people with a known allergy to eggs who want to receive YF vaccine should discuss this with an immunologist or allergist, or be referred to a specialised immunisation adverse events clinic. 

A few studies, predominantly in adults, have shown that YF vaccination is safe among egg-allergic people; however, because of varying expert guidelines, there are inconsistencies in practice involving varying protocols of skin prick testing, intradermal testing and graded dosing. Egg allergy is very common in children and as YF vaccine is important for protection and a requirement to enter some countries, the authors sought to assess the safety of YF vaccination in egg-allergic children. In this case series, the authors present their experience of successfully administering YF vaccine to 11 egg-allergic children, including 3 with anaphylaxis to egg, in two Australian tertiary paediatric hospitals, with no serious adverse events reported. 

The authors suggest that 2-dose graded challenge without skin testing may be a safe approach to vaccinate children with mild (non-anaphylactic) egg allergy.

Vaccination remains the most important strategy against YF. The YF vaccine is highly effective and provides long-term immunity in more than 95% people who get vaccinated. Clinicians should be advised that egg-allergic children needing YF vaccination should be referred to a specialist clinic for assessment and potential vaccination. 

Read the full case series here.