Direct and Indirect Benefits of Influenza Vaccine Versus Placebo in Healthy Children
|Influenza Virus Infection||Biological: Inactivated influenza vaccine Biological: Saline|
|Study Design:||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|
- The proportions of subjects and household contacts with serology-confirmed influenza infection during follow-up among the 2 intervention arms. [ Time Frame: nine months ]
|Study Start Date:||September 2008|
|Study Completion Date:||December 2010|
|Primary Completion Date:||December 2010 (Final data collection date for primary outcome measure)|
Active Comparator: 1
Biological: Inactivated influenza vaccine
0.5ml intramuscular single dose
Other Name: VAXIGRIP®, Sanofi Pasteur
|Placebo Comparator: 2||
0.5ml intramuscular, one dose
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.
Please refer to this study by its ClinicalTrials.gov identifier: NCT00792051
|The University of Hong Kong|
|Hong Kong, China|
|Principal Investigator:||Benjamin J Cowling, PhD||The University of Hong Kong|