Safety of quadrivalent live attenuated influenza vaccine in subjects aged 2-49years.
Quadrivalent live attenuated influenza vaccine (Q/LAIV) was licensed in 2012 and replaced trivalent live attenuated influenza vaccine in the United States during the 2013-2014 influenza season. This study assessed the safety of Q/LAIV in children and adults aged 2-49years.



This was a prospective observational cohort study using data collected from Kaiser Permanente Northern California. Post-vaccination events of interest were any hospitalization, hospitalization for lower respiratory tract infection, and the following medically attended events: hypersensitivity, seizures/convulsions, lower respiratory tract infection, wheezing, Guillain-Barré syndrome, Bell's palsy, encephalitis, neuritis, vasculitis, and narcolepsy/cataplexy. The rates of these events during the risk interval post-vaccination were compared with rates observed during reference periods later in the follow-up (within-cohort analysis) and with rates observed in frequency-matched unvaccinated controls and inactivated influenza vaccine (IIV) recipients.



A total of 62,040 eligible Q/LAIV recipients were identified during the 2013-2014 influenza season. Within-cohort comparisons of all Q/LAIV recipients as well as comparisons between Q/LAIV recipients and unvaccinated controls or IIV recipients did not show any significantly higher risk of hospitalizations or medically attended events following administration of Q/LAIV. Additional analyses by setting (clinic visits, emergency department visits, and hospital admissions) and age group (2-4, 5-8, 9-17, and 18-49years) also did not reveal clinically consistent findings that suggested any increased risk after administration of Q/LAIV.



In this large population study of individuals aged 2-49years, no safety signals associated with the administration of Q/LAIV were observed. A much larger study population would be needed to confidently reject any association between Q/LAIV and very rare events, specifically those with an incidence of <1 event/10,000 person-years.



ClinicalTrials.gov NCT01985997.
Kaiser Permanente Vaccine Study Center, 1 Kaiser Plaza, Ordway Building, 16th Floor, Oakland, CA 94612, United States.
Roger
R
Baxter
Kaiser Permanente Vaccine Study Center, 1 Kaiser Plaza, Ordway Building, 16th Floor, Oakland, CA 94612, United States.
Abigail
A
Eaton
Kaiser Permanente Vaccine Study Center, 1 Kaiser Plaza, Ordway Building, 16th Floor, Oakland, CA 94612, United States. Electronic address: john.hansen@kp.org.
John
J
Hansen
Kaiser Permanente Vaccine Study Center, 1 Kaiser Plaza, Ordway Building, 16th Floor, Oakland, CA 94612, United States.
Laurie
L
Aukes
AstraZeneca, One MedImmune Way, Gaithersburg, MD 20878, United States.
Herve
H
Caspard
AstraZeneca, One MedImmune Way, Gaithersburg, MD 20878, United States.
Christopher S
CS
Ambrose
D000293:Adolescent; D000328:Adult; D002140:California / Q000453:epidemiology; D002648:Child; D002675:Child, Preschool; D015331:Cohort Studies; D005260:Female; D020275:Guillain-Barre Syndrome / Q000209:etiology; D006760:Hospitalization; D006801:Humans; D007252:Influenza Vaccines / Q000008:administration & dosage / Q000009:adverse effects*; D007251:Influenza, Human / Q000453:epidemiology / Q000517:prevention & control*; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D012135:Respiratory Sounds / Q000209:etiology; D014611:Vaccination / Q000009:adverse effects; D014613:Vaccines, Attenuated / Q000008:administration & dosage / Q000009:adverse effects; D055815:Young Adult
D007252:Influenza Vaccines; D014613:Vaccines, Attenuated
Adults; Influenza vaccine; Paediatrics; Post-licensure safety; Quadrivalent live attenuated influenza vaccine