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Prophylactic effect of inactivated influenza vaccine on young children
Taro Maeda1, Yukihiro Shintani, Hajime Miyamoto
1Department of Pediatrics, Public Shisou General Hospital, Sikazawa 93, Yamasaki-Cho, Shisou-Gun, 671-2576 Hyogo, Japan. magotaro@arion.ocn.ne.jp
Insights
Inactivated influenza vaccine significantly reduced influenza A virus infection in children aged 2-6 years. The vaccine showed less effectiveness in children younger than 2 years old.
Area of Science:
- Pediatrics
- Immunology
- Infectious Diseases
Background:
- The efficacy of inactivated influenza vaccine (IIV) in young children has been debated.
- This study aimed to assess the protective effect of IIV in this age group.
Purpose of the Study:
- To evaluate the prophylactic efficacy of inactivated influenza vaccine in healthy infants and young children.
Main Methods:
- A cohort of 86 healthy children under 7 years received IIV before the 1999/2000 influenza season.
- 94 age-matched children served as a control group.
- Influenza A virus infection was diagnosed using rapid enzyme immunoassay membrane tests.
Main Results:
- Influenza A infection incidence was 5.8% in the vaccine group versus 17.0% in the control group (P = 0.016).
- The reduction in infection was statistically significant.
- However, 4 out of 5 infected children in the vaccine group were under 2 years old.
Conclusions:
- Inactivated influenza vaccine is effective in preventing influenza A virus infection in children aged 2-6 years.
- The vaccine's prophylactic effect appears diminished in children younger than 2 years.
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.
Conclusion:
We conclude that inactivated influenza vaccine reduces the incidence of influenza A virus infection in 2-6-year-old children.