British Medical Journal
14 January 2016 (vol 352, issue 8040)
http://www.bmj.com/content/352/8040

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Safety of live attenuated influenza vaccine in young people with egg allergy: multicentre prospective cohort study
BMJ 2015; 351 :h6291 (Published 08 December 2015)
Paul J Turner, clinician scientist and clinical senior lecturer1, honorary consultant2, Jo Southern, clinical research lead2, Nick J Andrews, senior statistician2, Elizabeth Miller, consultant epidemiologist2, Michel Erlewyn-Lajeunesse, consultant paediatric allergist3 on behalf of the SNIFFLE-2 Study
Abstract
Study question
How safe is live attenuated influenza vaccine (LAIV), which contains egg protein, in young people with egg allergy?
Methods
In this open label, phase IV intervention study, 779 young people (2-18 years) with egg allergy were recruited from 30 UK allergy centres and immunised with LAIV. The cohort included 270 (34.7%) young people with previous anaphylaxis to egg, of whom 157 (20.1%) had experienced respiratory and/or cardiovascular symptoms. 445 (57.1%) had doctor diagnosed asthma or recurrent wheeze. Participants were observed for at least 30 minutes after vaccination and followed-up by telephone 72 hours later. Participants with a history of recurrent wheeze or asthma underwent further follow-up four weeks later. The main outcome measure was incidence of an adverse event within two hours of vaccination in young people with egg allergy.
Study answer and limitations
No systemic allergic reactions occurred (upper 95% confidence interval for population 0.47% and in participants with anaphylaxis to egg 1.36%). Nine participants (1.2%, 95% CI 0.5% to 2.2%) experienced mild symptoms, potentially consistent with a local, IgE mediated allergic reaction. Delayed events potentially related to the vaccine were reported in 221 participants. 62 participants (8.1%, 95% CI for population 6.3% to 10.3%) experienced lower respiratory tract symptoms within 72 hours, including 29 with parent reported wheeze. No participants were admitted to hospital. No increase in lower respiratory tract symptoms occurred in the four weeks after vaccination (assessed with asthma control test). The study cohort may represent young people with more severe allergy requiring specialist input, since they were recruited from secondary and tertiary allergy centres.
What this study adds
LAIV is associated with a low risk of systemic allergic reactions in young people with egg allergy. The vaccine seems to be well tolerated in those with well controlled asthma or recurrent wheeze.
Funding, competing interests, data sharing
This report is independent research commissioned and funded by a Department of Health policy research programme grant to the National Vaccine Evaluation Consortium. Additional funding was provided by the NIHR Clinical Research Networks, Health Protection Scotland (Edinburgh site), and Health & Social Care Services in Northern Ireland (Belfast site). PJT and MEL had support from the Department of Health for the submitted work; PJT has received research grants from the Medical Research Council and NIHR. No additional data available.
Study registration
ClinicalTrials.gov (NCT02111512) and the EU Clinical Trials Register EudraCT (2014-001537-92).

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Editorials
Live attenuated influenza vaccine for children with egg allergy
BMJ 2015; 351 :h6656 (Published 09 December 2015)
Policies should change to allow vaccination, after compelling new evidence of safety.