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Direct and Indirect Benefits of Influenza Vaccine Versus Placebo in Healthy Children

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ClinicalTrials.gov Identifier: NCT00792051
Recruitment Status : Completed
First Posted : November 17, 2008
Last Update Posted : December 30, 2014
Information provided by:

Study Description
Brief Summary:
While immunisation of school-age children against influenza is not recommended in Hong Kong, past experience in Japan and elsewhere suggests that immunisation of children may protect the wider community through its indirect transmission-limiting impact as well as the direct immunologic protection afforded vaccinated children themselves. We aim to assess whether vaccinating children against influenza protects vaccinees as well as their household contacts from infection.

Condition or disease Intervention/treatment
Influenza Virus Infection Biological: Inactivated influenza vaccine Biological: Saline

Detailed Description:

Design and subjects: A double-blind randomised controlled trial of 800 subjects aged 6-17 drawn from the general population and their 2000 household contacts. The subjects will be randomised in a 3:2 ratio to the intervention and placebo groups, respectively. Serum samples will be collected from subjects pre- and 1 month post-vaccination, and after the influenza season. Serum samples will be collected from household contacts at baseline and at the end of the influenza season. During the follow-up period, subjects and household members will keep symptom diaries and those reporting influenza-like-illness will be offered free doctor consultations or home visits where we will arrange for collection of nose and throat swabs.

Study instruments: An antibody titre of ≥40 in the post-vaccine serum will be used to define seroprotection to those particular strains, while a four-fold or higher increase in antibody titres between baseline and end-of-season follow-up of the household contacts will define influenza infection during the season. Subjects and household contacts will be asked to keep symptom diaries, and during episodes of ILI we will collect nose and throat swabs for laboratory confirmation of influenza infection; the primary serology results will then be compared with clinical and laboratory-confirmed influenza episodes.

Interventions: 1 (intervention) inactivated influenza vaccine (Vaxigrip, Sanofi Pasteur); 2 (placebo) saline injection.

Main outcome measures: The proportions of subjects and household contacts with serology-confirmed influenza infection during follow-up among the 2 intervention arms.

Analysis: Intention to treat, adjusting for within-household correlation in influenza attack rates.

Study Design

Study Type : Interventional  (Clinical Trial)
Estimated Enrollment : 2800 participants
Allocation: Randomized
Intervention Model: Parallel Assignment
Masking: Triple (Participant, Care Provider, Outcomes Assessor)
Primary Purpose: Prevention
Official Title: A Randomised Controlled Trial of the Effectiveness of Vaccinating Children to Reduce Household Transmission of Influenza
Study Start Date : September 2008
Primary Completion Date : December 2010
Study Completion Date : December 2010

Resource links provided by the National Library of Medicine

MedlinePlus related topics: Flu Flu Shot
U.S. FDA Resources

Arms and Interventions

Arm Intervention/treatment
Active Comparator: 1
Influenza vaccine
Biological: Inactivated influenza vaccine
0.5ml intramuscular single dose
Other Name: VAXIGRIP®, Sanofi Pasteur
Placebo Comparator: 2 Biological: Saline
0.5ml intramuscular, one dose

Outcome Measures

Primary Outcome Measures :
  1. The proportions of subjects and household contacts with serology-confirmed influenza infection during follow-up among the 2 intervention arms. [ Time Frame: nine months ]

Eligibility Criteria

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Ages Eligible for Study:   Child, Adult, Senior
Sexes Eligible for Study:   All
Accepts Healthy Volunteers:   Yes

Inclusion Criteria:

  • All vaccinees must be Hong Kong residents aged between 6 and 17.

Exclusion Criteria:

  • Vaccinees should not be allergic or hypersensitive to the active substances or components (eggs, chicken proteins, formaldehyde, neomycin, etc.) used in the vaccines or where vaccination is otherwise contraindicated. Subjects should not have an underlying immunocompromised condition or be receiving immunosuppressive agents.
Contacts and Locations

Information from the National Library of Medicine

To learn more about this study, you or your doctor may contact the study research staff using the contact information provided by the sponsor.

Please refer to this study by its ClinicalTrials.gov identifier (NCT number): NCT00792051

The University of Hong Kong
Hong Kong, China
Sponsors and Collaborators
The University of Hong Kong
Research Fund for the Control of Infectious Diseases
The Research Grants Council, Hong Kong
Centre for Health Protection, Hong Kong
Principal Investigator: Benjamin J Cowling, PhD The University of Hong Kong
More Information

Publications automatically indexed to this study by ClinicalTrials.gov Identifier (NCT Number):
Responsible Party: Dr Benjamin John Cowling, The University of Hong Kong
ClinicalTrials.gov Identifier: NCT00792051     History of Changes
Other Study ID Numbers: GML003.4
First Posted: November 17, 2008    Key Record Dates
Last Update Posted: December 30, 2014
Last Verified: December 2014

Keywords provided by The University of Hong Kong:
Influenza-like illness

Additional relevant MeSH terms:
Influenza, Human
Virus Diseases
Orthomyxoviridae Infections
RNA Virus Infections
Respiratory Tract Infections
Respiratory Tract Diseases
Immunologic Factors
Physiological Effects of Drugs