Does influenza vaccination prevent asthma exacerbations in children?
OBJECTIVE
Influenza can exacerbate asthma, particularly in children. The effectiveness of influenza vaccine in preventing influenza-related asthma exacerbations, however, is not known. We evaluated influenza vaccine effectiveness in protecting children against influenza-related asthma exacerbations.


METHODS
We conducted a population-based retrospective cohort study with medical and vaccination records in 4 large health maintenance organizations in the United States during the 1993-1994, 1994-1995, and 1995-1996 influenza seasons. We studied children with asthma who were 1 through 6 years of age and who were identified by search of computerized databases of medical encounters and pharmacy dispensings. Main outcome measures were exacerbations of asthma evaluated in the emergency department or hospital.


RESULTS
Unadjusted rates of asthma exacerbations were higher after influenza vaccination than before vaccination. After adjustment was done for asthma severity by means of a self-control method, however, the incidence rate ratios of asthma exacerbations after vaccination were 0.78 (95% CI: 0.55 to 1.10), 0.59 (0.43 to 0.81), and 0.65 (0.52 to 0.80) compared with the period before vaccination during the 3 influenza seasons.


CONCLUSIONS
After controlling for asthma severity, we found that influenza vaccination protects against acute asthma exacerbations in children.
Kramarz
P
P
Centers for Disease Control and Prevention, Atlanta, Georgia 30333, USA.
Destefano
F
F
Gargiullo
P M
PM
Chen
R T
RT
Lieu
T A
TA
Davis
R L
RL
Mullooly
J P
JP
Black
S B
SB
Shinefield
H R
HR
Bohlke
K
K
Ward
J I
JI
Marcy
S M
SM
D000208:Acute Disease; D001249:Asthma / Q000453:epidemiology / Q000517:prevention & control* / Q000821:virology*; D002648:Child; D002675:Child, Preschool; D005260:Female; D006801:Humans; D007114:Immunization; D015994:Incidence; D007223:Infant; D007251:Influenza, Human / Q000150:complications / Q000517:prevention & control*; D008297:Male; D012044:Regression Analysis; D012189:Retrospective Studies; D012306:Risk; D012720:Severity of Illness Index; D014481:United States / Q000453:epidemiology