A postmarketing evaluation of the safety of Ann Arbor strain live attenuated influenza vaccine in adults 18-49 years of age.

ABSTRACT

BACKGROUND: The Ann Arbor strain-live attenuated influenza vaccine (LAIV) was licensed in 2003 for use in the United States for individuals aged 5-49 years of age. As part of a postmarketing commitment to safety, LAIV was studied in adults 18-49 years participating in the Kaiser Permanente Health Plan over 5 influenza seasons. METHODS: Individuals received LAIV as part of routine care from October 2003 through March 2008. Using Kaiser Permanente databases, rates of medically attended events (MAEs) and serious adverse events (SAEs) in LAIV recipients were compared with rates in multiple non-randomized control groups which included a self-control group, matched unvaccinated controls, and matched controls vaccinated with inactivated influenza vaccine (TIV). RESULTS: A total of 21,340, 18,316, and 21,340 subjects received LAIV, TIV and no vaccine, respectively. More than 5500 MAE incidence rate comparisons were performed, and of these, 257 (5%) yielded statistically significant differences with 72 and 185 occurring at a higher and lower rate after LAIV compared with control groups, respectively. The pattern of MAE rate differences did not suggest any safety signal associated with LAIV. There were 47 SAEs noted, and no individual SAE occurred at a significantly higher or lower rate in LAIV recipients relative to control groups in any comparison. Only 2 SAEs (migraine/sinusitis and Bell's palsy) were considered possibly or probably related to LAIV. CONCLUSION: The results of this post-licensure evaluation of LAIV safety in individuals 18-49 years of age are consistent with pre- and post-approval clinical studies as well as reports to the U.S. Vaccine Adverse Events Reporting System, all of which demonstrated no significant adverse outcomes among eligible individuals following receipt of LAIV.