Effect of influenza vaccination of children on infection rates in Hutterite communities: a randomized trial.
BACKGROUND
Children and adolescents appear to play an important role in the transmission of influenza. Selectively vaccinating youngsters against influenza may interrupt virus transmission and protect those not immunized.


OBJECTIVE
To assess whether vaccinating children and adolescents with inactivated influenza vaccine could prevent influenza in other community members.


METHODS
A cluster randomized trial involving 947 Canadian children and adolescents aged 36 months to 15 years who received study vaccine and 2326 community members who did not receive the study vaccine in 49 Hutterite colonies in Alberta, Saskatchewan, and Manitoba. Follow-up began December 28, 2008, and ended June 23, 2009.


METHODS
Children were randomly assigned according to community and in a blinded manner to receive standard dosing of either inactivated trivalent influenza vaccine or hepatitis A vaccine, which was used as a control.


METHODS
Confirmed influenza A and B infection using a real-time reverse transcriptase polymerase chain reaction (RT-PCR) assay and by measuring serum hemagglutination inhibition titers.


RESULTS
The mean rate of study vaccine coverage among eligible participants was 83% (range, 53%-100%) for the influenza vaccine colonies and 79% (range, 50%-100%) for the hepatitis A vaccine colonies. Among nonrecipients, 39 of 1271 (3.1%) in the influenza vaccine colonies and 80 of 1055 (7.6%) in the hepatitis A vaccine colonies had influenza illness confirmed by RT-PCR, for a protective effectiveness of 61% (95% confidence interval [CI], 8%-83%; P = .03). Among all study participants (those who were and those who were not vaccinated), 80 of 1773 (4.5%) in the influenza vaccine colonies and 159 of 1500 (10.6%) in the hepatitis A vaccine colonies had influenza illness confirmed by RT-PCR for an overall protective effectiveness of 59% (95% CI, 5%-82%; P = .04). No serious vaccine adverse events were observed.


CONCLUSIONS
Immunizing children and adolescents with inactivated influenza vaccine significantly protected unimmunized residents of rural communities against influenza.


BACKGROUND
clinicaltrials.gov Identifier: NCT00877396.
Loeb
Mark
M
Department of Pathology and Molecular Medicine, McMaster University, 1200 Main St W, Hamilton, ON, L8N 3Z5 Canada. loebm@mcmaster.ca
Russell
Margaret L
ML
Moss
Lorraine
L
Fonseca
Kevin
K
Fox
Julie
J
Earn
David J D
DJ
Aoki
Fred
F
Horsman
Gregory
G
Van Caeseele
Paul
P
Chokani
Khami
K
Vooght
Mark
M
Babiuk
Lorne
L
Webby
Richard
R
Walter
Stephen D
SD
D000293:Adolescent; D000328:Adult; D000367:Age Factors; D000368:Aged; D002170:Canada / Q000453:epidemiology; D002648:Child; D002675:Child, Preschool; D004311:Double-Blind Method; D005260:Female; D022362:Hepatitis A Vaccines / Q000008:administration & dosage; D006801:Humans; D009980:Influenza A virus / Q000235:genetics / Q000276:immunology; D009981:Influenza B virus / Q000235:genetics / Q000276:immunology; D007252:Influenza Vaccines / Q000008:administration & dosage*; D007251:Influenza, Human / Q000453:epidemiology* / Q000517:prevention & control* / Q000635:transmission; D008297:Male; D008875:Middle Aged; D012067:Religion; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012424:Rural Population; D055815:Young Adult
D022362:Hepatitis A Vaccines; D007252:Influenza Vaccines