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Effectiveness of vaccinating children in reducing influenza among household contacts – a community-based, randomized controlled trial |
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| Funds
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Research Fund for the Control of Infectious Diseases (commissioned projects) |
| Project
Status |
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Current |
| Reference
No. |
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CHP-CE-03 |
| Project
Title |
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Effectiveness of vaccinating children in reducing influenza among household contacts – a community-based, randomized controlled trial |
| Applicant(s) |
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BJ Cowling
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| Affiliation(s) |
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Centre for Health Protection
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| Approved
Amount (HK$) |
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$6,628,154.00 |
| Abstract |
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Background: 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 as well as the children themselves.
Aim: To assess whether vaccinating children against influenza protects household contacts from infection.
Design and subjects: A placebo-controlled, double-blind randomised controlled trial of 800 subjects aged 6-18 drawn from the general population and their 2000 household contacts. The subjects will be randomised in a 3:2 ratio to the intervention and control groups, respectively. Serum samples will be collected from all subjects pre- and 1 month post-vaccination, and after the 'flu season. Serum samples will be collected from household contacts at baseline and at the end of the 'flu season. During the follow-up period, subjects and household members will be monitored for influenza-like-illnesses and will be offered free doctor consultations or home visits where we will arrange for collection of nose and throat swabs.
Study instruments: Serum samples with a four-fold or higher increase in antibody titer between pre- and post-vaccination will be taken to indicate seroprotection to those particular strains, while a four-fold or higher increase in antibody titers between baseline and end-of-season follow-up of the household contacts will define influenza infection during the season. Nose and throat swabs collected during follow-up will be tested for laboratory confirmation of influenza infection.
Interventions: 1 (intervention) inactivated influenza vaccine (Vaxigrip, Sanofi Pasteur); 2 (control) saline.
Main outcome measures: The proportions of subjects and household contacts with serologically-confirmed influenza during follow-up among the 2 intervention arms.
Analysis: Intention to treat, adjusting for within-household correlation in influenza attack rates. |
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