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

Influenza Virus Infection Clinical Trial

Official title:

A Randomised Controlled Trial of the Effectiveness of Vaccinating Children to Reduce Household Transmission of Influenza

Clinical Trial Details — Status: Completed

Administrative data

• NCT number: NCT00792051
• Other study ID #: GML003.4
• Status: Completed
• Phase: N/A
• First received: November 13, 2008
• Last updated: December 29, 2014
• Start date: September 2008
• Est. completion date: December 2010

Study information

• Verified date: December 2014
• Source: The University of Hong Kong
• Contact: n/a
• Is FDA regulated: No
• Health authority: Hong Kong: Centre for Health Protection
• Study type: Interventional

Clinical Trial 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.

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.

Recruitment information / eligibility

• Status: Completed
• Enrollment: 2800
• Est. completion date: December 2010
• Est. primary completion date: December 2010
• Accepts healthy volunteers: Accepts Healthy Volunteers
• Gender: Both
• Age group: N/A and older

Eligibility

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.

Study Design

Allocation: Randomized, Endpoint Classification: Efficacy Study, Intervention Model: Parallel Assignment, Masking: Double Blind (Subject, Caregiver, Outcomes Assessor), Primary Purpose: Prevention

Related Conditions & MeSH terms

• Influenza Virus Infection
• Influenza, Human
• Virus Diseases

Intervention

Biological:
• Inactivated influenza vaccine
0.5ml intramuscular single dose
• Saline
0.5ml intramuscular, one dose

Locations

Country	Name	City	State
China	The University of Hong Kong	Hong Kong

Sponsors (4)

Lead Sponsor	Collaborator
The University of Hong Kong	Centre for Health Protection, Research Fund for the Control of Infectious Diseases, The Research Grants Council, Hong Kong

Country where clinical trial is conducted

China, 

References & Publications (2)

Cowling BJ, Ng S, Ma ES, Cheng CK, Wai W, Fang VJ, Chan KH, Ip DK, Chiu SS, Peiris JS, Leung GM. Protective efficacy of seasonal influenza vaccination against seasonal and pandemic influenza virus infection during 2009 in Hong Kong. Clin Infect Dis. 2010 — View Citation

Cowling BJ, Ng S, Ma ES, Fang VJ, So HC, Wai W, Cheng CK, Wong JY, Chan KH, Ip DK, Chiu SS, Peiris JS, Leung GM. Protective efficacy against pandemic influenza of seasonal influenza vaccination in children in Hong Kong: a randomized controlled trial. Clin — View Citation

Outcome

Type	Measure	Description	Time frame	Safety issue
Primary	The proportions of subjects and household contacts with serology-confirmed influenza infection during follow-up among the 2 intervention arms.		nine months	No