Adverse events reported following live, cold-adapted, intranasal influenza vaccine.
BACKGROUND
In June 2003, the US Food and Drug Administration licensed a trivalent live, attenuated influenza vaccine (LAIV-T) for intranasal administration to healthy persons 5 to 49 years of age. Although prelicensure testing involved 20 228 vaccinees, clinical trials were not of sufficient size to detect rare adverse events reliably.


OBJECTIVE
To identify adverse events reported following LAIV-T administration after licensure.


METHODS
All adverse events reported to the US Vaccine Adverse Event Reporting System (VAERS) during the 2003-2004 and the 2004-2005 influenza seasons.


METHODS
Numbers and proportions of reported adverse events and reporting rates of adverse events per 100,000 vaccinees.


RESULTS
Approximately 2,500,000 persons received LAIV-T during the first 2 postlicensure seasons. As of August 16, 2005, VAERS received 460 adverse event reports for vaccinations received from August 2003 through July 2005. No fatalities were reported. There were 7 reports of possible anaphylaxis, 2 reports of Guillain-Barré syndrome, 1 report of Bell palsy, and 8 reports of asthma exacerbation among individuals with a prior asthma history. Events in individuals for whom the vaccine was not indicated accounted for 73 reports (16%).


CONCLUSIONS
Reports to VAERS in the first 2 seasons of LAIV-T use did not identify any unexpected serious risks with this vaccine when used according to approved indications. Like many vaccines and other medical products, LAIV-T may rarely cause anaphylaxis. Secondary transmission of the vaccine virus merits further investigation. Reports of asthma exacerbations in vaccinees with prior asthma history highlight the risks of vaccine use inconsistent with approved labeling.
Izurieta
Hector S
HS
Center for Biologics Evaluation and Research, Food and Drug Administration, Rockville, Md 20852-1448, USA. hector.izurieta@fda.hhs.gov
Haber
Penina
P
Wise
Robert P
RP
Iskander
John
J
Pratt
Douglas
D
Mink
ChrisAnna
C
Chang
Soju
S
Braun
M Miles
MM
Ball
Robert
R
D000281:Administration, Intranasal; D000293:Adolescent; D000328:Adult; D016907:Adverse Drug Reaction Reporting Systems; D000368:Aged; D002648:Child; D002675:Child, Preschool; D005260:Female; D006801:Humans; D007252:Influenza Vaccines / Q000008:administration & dosage / Q000009:adverse effects*; D008297:Male; D008875:Middle Aged; D012306:Risk; D014481:United States / Q000453:epidemiology; D014613:Vaccines, Attenuated / Q000009:adverse effects
D007252:Influenza Vaccines; D014613:Vaccines, Attenuated