Prophylactic effect of inactivated influenza vaccine on young children.
BACKGROUND
The effectiveness of inactivated influenza vaccine in healthy infants and young children has been controversial. The aim of this study was to determine the prophylactic effect of inactivated influenza vaccine in young children.


METHODS
Eighty-six healthy infants and children younger than 7-years-old were immunized by a subcutaneous injection of inactivated influenza vaccine before the 1999/2000 influenza season. Ninety-four age-matched children were randomly assigned as the control. These children were followed-up from January to April, 2000. A diagnosis of influenza A virus infection was made rapidly by a positive result of the the enzyme immunoassay membrane test using enzyme-conjugated monoclonal antibodies specific for a conserved epitope of influenza A nucleoprotein. The incidence of influenza A infection was compared and statistically assessed.


RESULTS
The prevalence of influenza A virus infection, diagnosed by the influenza A rapid detection test, was 5.8% in the vaccine group and 17.0% in the control group, that is significantly lower in the vaccine receiving group than the non-receiving group (P = 0.016). However, four out of five infected children in the vaccine group were younger than 2-years-old.


CONCLUSIONS
We conclude that inactivated influenza vaccine reduces the incidence of influenza A virus infection in 2-6-year-old children.
Maeda
Taro
T
Department of Pediatrics, Public Shisou General Hospital, Sikazawa 93, Yamasaki-Cho, Shisou-Gun, 671-2576 Hyogo, Japan. magotaro@arion.ocn.ne.jp
Shintani
Yukihiro
Y
Miyamoto
Hajime
H
Kawagoe
Hiroyuki
H
Nakano
Kanako
K
Nishiyama
Atsusi
A
Yamada
Yoshiyasu
Y
D002648:Child; D002675:Child, Preschool; D005260:Female; D006801:Humans; D007223:Infant; D009980:Influenza A virus; D007252:Influenza Vaccines / Q000627:therapeutic use*; D007251:Influenza, Human / Q000517:prevention & control*; D008297:Male; D015164:Vaccines, Inactivated / Q000627:therapeutic use*
D007252:Influenza Vaccines; D015164:Vaccines, Inactivated