NCT00792051

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

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

• Status: Completed
• Phase: N/A
• Study type: Interventional
• Enrollment: 2,800 (estimated)
• Sponsor: The University of Hong Kong · Academic / Other
• Sex: All
• Age: —
• Healthy volunteers: Accepted

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.

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.

Conditions

• Influenza Virus Infection

Interventions

Type	Name	Description
BIOLOGICAL	Inactivated influenza vaccine	0.5ml intramuscular single dose
BIOLOGICAL	Saline	0.5ml intramuscular, one dose

Timeline

• Start date: 2008-09-01
• Primary completion: 2010-12-01
• Completion: 2010-12-01
• First posted: 2008-11-17
• Last updated: 2014-12-30

Locations

1 site across 1 country: China