Live Attenuated Vaccine Safe for Children With Egg Allergy

Live-attenuated influenza vaccine (LAIV), administered intranasally, is unlikely to trigger systemic allergic reactions in children (aged 2 - 18 years) with egg allergy and is well tolerated in those with well-controlled asthma or recurrent wheeze. The results are from a new multicenter study by Paul J. Turner, PhD, from the Imperial College London and Public Health England, United Kingdom, and colleagues, published online December 8 in the BMJ.

The researchers recruited 779 children during the September 2014 to February 2015 influenza season to receive at least one dose of LAIV. All children had a physician diagnosis of egg allergy, and 270 (34.7%) had a previous anaphylaxis to egg. In addition, asthma or recurrent wheeze had been diagnosed in 445 (57.1%) of participants.

After vaccination, participants were monitored for 30 minutes, and a follow-up telephone call was made 72 hours later. For children with asthma or recurrent wheeze, the asthma control test was performed at the time of vaccination, and again 4 weeks later.

The researchers found that no systemic allergic reactions occurred within 2 hours of vaccination (upper 95% confidence interval [CI] for the overall population was 0.47% vs 1.36% for participants with anaphylaxis to egg). Nine participants (1.2%; 95% CI, 0.5% - 2.2%) experienced mild, self-limiting adverse events including rhinitis, urticaria, and oropharyngeal itch. These events were thought to be associated with a local, immunoglobulin E–mediated allergic reaction. Aside from a higher incidence of a possible reaction among participants with a history of reaction to aerosolized egg, no risk factors were identified.

Delayed events were noted in 221 participants, including 62 (8.1%) with lower respiratory tract symptoms within 72 hours (95% CI, 6.3% - 10.3%). None of these participants was hospitalized, and no risk factors were identified for the occurrence of delayed events.

The researchers also found that there was no significant change in the asthma control test score from baseline in the 4 weeks after vaccination in children aged 12 years or older (P = .12). A small improvement in this score was noted, however, for children aged from 2 to 11 years (P < .001).

"This study confirms our previous findings that LAIV is unlikely to trigger a systemic allergic reaction in young people with egg allergy," the investigators say.

The authors conclude that, "with the exception of children with severe anaphylaxis to egg which has previously required intensive care, children with a history of egg allergy can be safely vaccinated with [LAIV]." They do stress however, that staff should be trained in how to recognize and treat anaphylaxis, should it occur.

Funding for this study was provided through a grant from the Department of Health policy research program, the National Institute for Health Research Clinical Research Networks, Health Protection Scotland, and Health and Social Care Services of Northern Ireland. The authors have disclosed no relevant financial relationships.

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