Safety of the trivalent inactivated influenza vaccine among children: a population-based study.
BACKGROUND
To our knowledge, there are no published population-based studies on the safety of the inactivated trivalent influenza vaccine among children.


OBJECTIVE
To screen a large population of children for evidence of increased medical visits in the 2 weeks after influenza vaccination compared with 2 control periods. Secondary analyses included shorter risk periods and restricted age categories.


METHODS
Self-control screening analysis. Children vaccinated from January 1, 1993, through December 31, 1999, were randomly divided into 2 equal groups. In group 1, risks of outpatient, emergency department, and inpatient visits during the 14 days after vaccination were compared with the risks of visits in 2 control periods. Significant plausible medically attended events identified in group 1 were then analyzed in group 2, using the same 2 control periods. Medically attended events significant in both groups were considered potentially associated with vaccination and were assessed by medical record review.


METHODS
Five managed care organizations in the United States.


METHODS
Children younger than 18 years who received an influenza vaccination in one of the managed care settings (N = 251 600).


METHODS
Among vaccinated children seen for a medically attended event, the odds of the visit occurring in the 2 weeks after vaccination vs during 1 of the 2 control periods.


RESULTS
Study participants incurred 1165, 230, and 489 different diagnoses during the 14 days after vaccination according to the outpatient, emergency department, and inpatient data, respectively. Four diagnoses were positively associated with the vaccine in both groups 1 and 2: impetigo, dermatitis, uncomplicated diabetes mellitus, and ureteral disorder not otherwise specified. After medical record review, impetigo (9 cases) in children 6 to 23 months old remained significantly associated with vaccination.


CONCLUSIONS
This large screening safety study did not reveal any evidence of important medically attended events associated with pediatric influenza vaccination.
France
Eric K
EK
Clinical Research Unit, Kaiser Permanente Colorado, Denver, USA. eric.k.france@kp.org
Glanz
Jason M
JM
Xu
Stanley
S
Davis
Robert L
RL
Black
Steven B
SB
Shinefield
Henry R
HR
Zangwill
Kenneth M
KM
Marcy
S Michael
SM
Mullooly
John P
JP
Jackson
Lisa A
LA
Chen
Robert
R
D016022:Case-Control Studies; D002648:Child; D016001:Confidence Intervals; D018592:Cross-Over Studies; D005260:Female; D006279:Health Maintenance Organizations; D006801:Humans; D007223:Infant; D007252:Influenza Vaccines / Q000009:adverse effects*; D008297:Male; D008498:Medical Record Linkage; D011159:Population Surveillance / Q000379:methods*; D014481:United States
D007252:Influenza Vaccines