A Postmarketing Evaluation of the Frequency of Use and Safety of Live Attenuated Influenza Vaccine In Non-Recommended Children Less Than 59 Months of Age

Background: The 2007 US approval for use of live attenuated influenza vaccine (LAIV) in children aged 24–59 months included precautions against use in: 1) children <24 months and children aged 24–59 months with 2) asthma, 3) recurrent wheezing, and 4) altered immunocompetence.

Objectives:  None.

Methods: Children were identified from a national, anonymized insurance claims database covering 17 million individuals. The 4 pediatric cohorts were defined using diagnosis codes, prescription claims, and national guidelines. Rates of LAIV and trivalent inactivated influenza vaccine (TIV) use in the 2007–2008 through 2009–2010 seasons were calculated, as were the frequencies of hospitalization and emergency department (ED) visits within 42 days following vaccination in the 2007–2008 and 2008–2009 seasons (2009–2010 analysis pending). Use in the general population of 24–59 month old children was calculated for context.

Results: In seasons 1, 2, and 3, 12,479, 67,657, 70,502 LAIV vaccinations among children <59 months of age were noted, respectively. In all 3 seasons, LAIV vaccination rates among children in cohorts 1, 2, and 4 were substantially lower than among children aged 24–59 months recommended for LAIV, while LAIV use among children with recurrent wheezing (cohort 3) was similar. Overall and by specific diagnosis, there was no increased rate of ED visits or hospitalizations within 42 days of vaccination in children vaccinated with LAIV compared with TIV in each of the 4 cohorts.

Conclusions:  Healthcare providers appear to be complying with the indications for the use of LAIV in children aged <5 years; use does not appear to be restricted in children with recurrent wheezing. In the small number of children vaccinated, there was no increased rate of ED visits or hospitalizations after LAIV administration. Sponsored by MedImmune.