Related Experiment Video

Updated: Aug 15, 2026

An Optimized Hemagglutination Inhibition (HI) Assay to Quantify Influenza-specific Antibody Titers
06:34

An Optimized Hemagglutination Inhibition (HI) Assay to Quantify Influenza-specific Antibody Titers

Published on: December 1, 2017

Inactivated influenza vaccine effectiveness in children under 6 years of age during the 2002-2003 season

Megumi Fujieda1, Akiko Maeda, Kyoko Kondo

  • 1Department of Public Health, Osaka City University Faculty of Medicine, Japan. megmeg@med.osaka-cu.ac.jp

Vaccine
|September 21, 2005
PubMed

Insights

This study found influenza vaccine effectiveness of 24% in children under six. Vaccine effectiveness was higher, 33%, in children aged two and older, but not significant in very young children.

Area of Science:

  • Pediatrics
  • Vaccinology
  • Epidemiology

Background:

  • Influenza poses a significant health risk to children.
  • Assessing influenza vaccine effectiveness is crucial for public health strategies.

Purpose of the Study:

  • To evaluate the effectiveness of the influenza vaccine in children under six years of age during the 2002-2003 influenza season in Japan.

Main Methods:

  • A cohort study involving 2913 children (1512 vaccinated, 1401 unvaccinated) across 54 pediatric clinics.
  • Influenza-like illness (ILI) was defined as acute febrile illness (≥38.0°C) during peak epidemic periods.
  • Vaccine effectiveness was calculated using logistic regression to compare ILI frequencies between vaccinated and unvaccinated groups, determining adjusted odds ratios (OR) and 95% confidence intervals (95% CI).

Main Results:

  • Overall vaccine effectiveness was 24% (95% CI: 12%-34%), with a decreased odds ratio (OR: 0.76) for ILI in vaccinated children.
  • In children aged two years and older, vaccine effectiveness was more pronounced at 33% (95% CI: 21%-44%), with an OR of 0.67.
  • No statistically significant vaccine effectiveness was observed in children younger than two years (ORs ranging from 0.81 to 4.19).

Conclusions:

  • The influenza vaccine demonstrated moderate effectiveness in children under six, particularly in those aged two and older.
  • Effectiveness was not demonstrated in very young children (under two years), suggesting potential age-specific variations in vaccine response.
  • These findings highlight the importance of age stratification when evaluating influenza vaccine efficacy in pediatric populations.

More Related Videos

Measuring Influenza Neutralizing Antibody Responses to A(H3N2) Viruses in Human Sera by Microneutralization Assays Using MDCK-SIAT1 Cells12:09

Measuring Influenza Neutralizing Antibody Responses to A(H3N2) Viruses in Human Sera by Microneutralization Assays Using MDCK-SIAT1 Cells

Published on: November 22, 2017

A Luciferase-fluorescent Reporter Influenza Virus for Live Imaging and Quantification of Viral Infection05:21

A Luciferase-fluorescent Reporter Influenza Virus for Live Imaging and Quantification of Viral Infection

Published on: August 14, 2019

Related Concept Videos

Vaccinations01:51

Vaccinations

Overview
Influenza01:27

Influenza

Influenza is an acute, highly communicable viral disease that affects the respiratory tract and is responsible for seasonal epidemics worldwide. Influenza A is the most prevalent type associated with widespread outbreaks and is subtyped based on two surface glycoproteins: hemagglutinin (H) and neuraminidase (N), as in H1N1. These glycoproteins are essential for viral infectivity, transmission, and immune recognition. Transmission occurs primarily through respiratory droplets and contaminated...
Poliomyelitis01:17

Poliomyelitis

Poliomyelitis is caused by poliovirus, a small, non-enveloped, positive-sense RNA virus of the Picornaviridae family and Enterovirus genus. Transmission occurs primarily via the fecal-oral route, often through ingestion of contaminated water or food. The virus initially replicates in the oropharynx and intestinal mucosa, particularly in lymphoid tissues such as the tonsils, Peyer’s patches, and regional lymph nodes. Primary viremia follows, allowing dissemination throughout the body.In most...