Influenza Vaccine Feasibility Study in Children With Persistent Asthma

The association of an increased risk in wheezing following receipt of a live-attenuated influenza vaccine in children at least 2 years of age with a prior history of asthma or wheeze remains unclear. The Centers for Disease Control (CDC) and Prevention's Clinical Immunization Safety Assessment (CISA) planned to address a data safety gap regarding use of LAIV4 vaccine in children with asthma by conducting a 3-site randomized, non-inferiority prospective study. The main goal was to compare the safety of LAIV4 versus IIV4 in children 5-11 years with persistent asthma during the 2016-2017 influenza season. CDC and the CISA study sites developed a protocol and associated materials, and were poised to begin enrollment early during the 2016-2017 influenza season. However, after the June 22, 2016 Advisory Committee on Immunization Practices (ACIP) vote recommending against use of LAIV4 during the 2016-2017 influenza season, CDC and study investigators decided to defer implementing a study using LAIV4 during the 2016-2017 influenza season. Investigators will reconsider initiating this study during the 2017-2018 influenza season if ACIP votes to reinstate LAIV4 use or new data become available; ACIP makes recommendations annually. The planned LAIV4 study had unique features in its design that previously had not been implemented in vaccine safety studies, including: 1) enrolling a substantial proportion of children with moderate-severe asthma 2) using digital peak flow meters and 3) collecting clinical data through multiple, complementary, measures for 42 days after vaccination. To capitalize on progress made during development of the study protocol and associated documents and procedures, CISA is proposing to carry out a study at the three sites to assess the feasibility of recruiting, enrolling, retaining, and collecting clinical data on children 5-11 years with persistent asthma of varied levels of severity in an influenza vaccine safety study. Findings from this proposed feasibility study will facilitate improving the LAIV4 study in the future if it goes forward through the CISA Project or in another venue. In 2016-2017 season, FDA approved a new influenza vaccine for use in persons aged 4 years and older, Flucelvax® Quadrivalent (ccIIV4); ACIP incorporated this vaccine into its recommendations for the 2016-2017 influenza season. Therefore ccIIV4 will be used in place of LAIV4 for this feasibility study. There is no evidence that Flucelvax® increases the risk of wheezing in asthmatic children. The feasibility study also offers an opportunity to gain some additional descriptive safety data for this new vaccine in asthmatic children.