Live Attenuated Influenza Vaccine: Will the Phoenix Rise Again?

* Abbreviations: ACIP —: Advisory Committee on ImmunizationA/H1N1pdm09 —: influenza A/H1N1 2009IIV —: inactivated influenzaLAIV —: live attenuated influenzaLAIV3 —: live attenuated influenza vaccine–trivalent LAIV4 —: live attenuated influenza vaccine–quadrivalentThe live attenuated influenza vaccine (LAIV) (FluMist) has undergone a roller coaster journey since its licensure in 2003 for eligible individuals 5 to 49 years of age and subsequent expansion to children 2 to 4 years of age in 2007. LAIV was the first new influenza vaccine approved in the United States since the introduction of the inactivated influenza vaccine (IIV) developed in the 1940s. Authors of studies performed before the influenza A/H1N1 2009 pandemic (A/H1N1pdm09) suggested that LAIV was more efficacious than IIV in pediatric populations.1 The Advisory Committee on Immunization Practices (ACIP) from the Centers for Disease Control and Prevention recommended preferential use of the LAIV for eligible children 2 to 8 years of age in the 2014–2015 season, removed the preferential recommendation in the 2015–2016 season, and provided interim recommendation against its use during the 2016–2017 and 2017–2018 seasons because of observational studies suggesting effectiveness that would be lower than expected against the A/H1N1pdm09.2–5The study by Chung et al,6 “Live Attenuated and Inactivated Influenza Vaccine Effectiveness” in this issue of Pediatrics is a meta-analysis from 5 observational programs conducted from 2013–2014 through 2015–2016 comparing vaccine effectiveness between live … Address correspondence to Pedro A. Piedra, MD, Department of Molecular Virology and Microbiology, Baylor College of Medicine, 1 Baylor Plaza, Houston, TX 77030. E-mail: ppiedra{at}bcm.edu