Safety of live attenuated influenza vaccine (LAIV) in children with moderate to severe asthma

Abstract Background Live attenuated influenza vaccine (LAIV) is recommended for annual influenza vaccination in children from age 2 years. However, some guidelines recommend against its use in children with asthma or recurrent wheeze due to concerns over its potential to induce wheezing. Objective To assess the safety of LAIV in children with moderate-severe asthma, and in preschool children with recurrent wheeze. Methods Prospective, multi-center, open label, phase IV intervention study in 14 specialist UK clinics. LAIV was administered under medical supervision, with follow-up of asthma symptoms 72 hours and 4 weeks late, using validated questionnaires. ClinicalTrials.gov registration NCT02866942, EU Clinical Trials registration 2016-002352-24. Results 478 young people (median 9.3, range 2–18 years) with physician-diagnosed asthma or recurrent wheeze were recruited, including 208 (44%) prescribed high-dose inhaled corticosteroids and 122 (31%) with severe asthma. There was no significant change in asthma symptoms in the 4 weeks following administration (median change 0, P=.26, McNemar’s test), with no impact of level of baseline asthma control/symptoms in predicting either a worsening of asthma or exacerbation following LAIV using a regression model. 47 subjects (14.7%, 95%CI 11% to 19.1%) reported a severe asthma exacerbation in the four weeks following immunization, requiring short course of systemic corticosteroids; in four cases, this occurred within 72 hours of vaccine. No association with asthma severity, baseline lung function or asthma control was identified. Conclusions LAIV appears to be well-tolerated in the vast majority of children with asthma or recurrent wheeze, including those whose asthma is categorized as severe or poorly controlled.