Safety of the Intranasal, Trivalent, Live Attenuated Influenza Vaccine (LAIV) in Children With Intermittent Wheezing in an Open-Label Field Trial

Abstract

Background: Safety of the intranasal, trivalent, live attenuated influenza vaccine (LAIV) in children with asthma is unknown. A previous report showed an “asthma signal” in children aged 18–35 months. Methods: Healthy children aged 1.5–18 years with history of intermittent wheezing received single annual LAIV doses during a 4-year trial. Rates of medically-attended acute respiratory illnesses, including acute asthma exacerbation, during 0–14 and 0–42 days post-LAIV were compared with respective reference periods (before day 0 and after 14 or 42 days). To assess the risk of new-onset asthma, LAIV recipients without history of wheezing were analyzed. Results: During each of the 4 years, 454, 656, 656, and 430 children, respectively, with intermittent wheezing who received LAIV had no increased risk for medically-attended acute respiratory illnesses, including asthma exacerbation. First-dose LAIV recipients, including those aged 1.5–4 years, and those receiving 2–4 consecutive annual doses had no increased risk. Children with parents' report of intermittent wheezing and those with administrative database codes for asthma during 2 prior years had no increased risk. During the 4 years, 2952, 3092, 2953, and 2478 children without history of wheezing had no increased risk of new-onset asthma. Conclusions: LAIV administration in children aged 1.5–18 years with history of intermittent wheezing was safe, and was not associated with increased risk for medically-attended acute respiratory illnesses, including acute asthma exacerbation. This was true for the first and 2–4 consecutive annual doses. Parents' report of intermittent wheezing was reliable. First-dose LAIV was not associated with new-onset asthma in children without history of wheezing.