Failure of inactivated influenza A vaccine to protect healthy children aged 6-24 months.
BACKGROUND
The efficacy of inactivated influenza vaccine in healthy infants and children younger than 24 months has not been confirmed. The aim of the present study was to determine the prophylactic effect of inactivated influenza vaccine against influenza A in healthy children aged 6-24 months.


METHODS
Healthy infants and young children (6-24 months old) were immunized by subcutaneous injection of inactivated influenza vaccine before influenza seasons. Age matched children were randomly assigned as the control. These children were followed up from January to April in each year (2000, 2001 and 2002). The attack rates of influenza A infection was compared and statistically assessed.


RESULTS
The attack rate of influenza A virus infection in the vaccine group and the control group were 14.8% (n = 27) vs 12.5% (n = 32) in 2000 (P = 0.526); 2.8% (n = 72) vs 7.2% (n = 69) in 2001 (P = 0.203); and 3.4% (n = 52) vs 8.9% (n = 56) in 2002 (P = 0.205). The attack rates of influenza A between the two groups were not significantly different.


CONCLUSIONS
Inactivated influenza vaccine did not reduce the attack rate of influenza A infection in 6-24 month old children.
Maeda
Taro
T
Department of Pediatrics, Public Shisou General Hospital, Shisou, Japan. magotaro@kcc.zaq.ne.jp
Shintani
Yukihiro
Y
Nakano
Kanako
K
Terashima
Kazuhiro
K
Yamada
Yoshiyasu
Y
D002675:Child, Preschool; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007223:Infant; D009980:Influenza A virus; D007252:Influenza Vaccines / Q000627:therapeutic use*; D007251:Influenza, Human / Q000517:prevention & control*; D008297:Male; D017211:Treatment Failure; D015164:Vaccines, Inactivated / Q000627:therapeutic use
D007252:Influenza Vaccines; D015164:Vaccines, Inactivated