Safety of guidelines recommending live attenuated influenza vaccine for routine use in children and adolescents with asthma

Objective: Evaluate whether a guideline recommending Live Attenuated Influenza Vaccine (LAIV) for children 2 years and older with asthma increased risks for lower respiratory events (LREs), within 21 or 42 days of vaccination, as compared to standard guidelines to administer Inactivated Influenza Vaccine (IIV) in children with asthma. Methods: This was a pre/post guideline retrospective cohort study of children ages 2-17 years with asthma and receiving one or more influenza vaccines in two large medical groups from 2007 to 2016. Both groups recommended IIV in the pre-period; in 2010, one group implemented a guideline recommending LAIV for all children, including those with asthma. Main outcomes were medically attended LREs within 21 and 42 days after influenza immunization. Analysis used a generalized estimating equation regression to estimate the ratio of rate ratios (RORs) comparing pre/post events between LAIV guideline and control group. Results: The cohort included 7851 influenza vaccinations in 4771 children with asthma. Among patients in the LAIV guideline group, the proportion receiving LAIV increased from 23% to 68% post-guideline implementation, versus an increase from 7 to 11% in the control group. Age and baseline asthma severity adjusted ROR showed no increase in LREs, primarily asthma exacerbations, following implementation of the LAIV guideline: overall aROR (95% Confidence Interval): 0.74 (0.43-1.29) for LRE within 21 days of vaccination, 0.77 (0.53-1.14) for LRE within 42 days of vaccination. For the subset of children ages 2-4 years aROR: 0.92 (0.34-2.53) for LRE within 21 days of vaccination and 0.94 (0.49-1.82) for LRE within 42 days of vaccination; for children 5-18 years aROR (95% CI): 0.58 (0.26-1.30) for LRE within 21 days of vaccination and 0.67 (0.37-1.23) for LRE within 42 days. Conclusion: In a large cohort of children with asthma, a guideline recommending LAIV rather than IIV did not increase LREs following vaccination. (C) 2019 Elsevier Ltd. All rights reserved.