Imunização contra Influenza em Crianças e Adolescentes em Áreas Rurais - Um estudo randomizado

Effect of Influenza Vaccination of Children

on Infection Rates in Hutterite Communities: A Randomized Trial

Mark Loeb; Margaret L. Russell; Lorraine Moss; et al

Context

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.

Design, Setting, and Participants

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.

Intervention

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.

Main Outcome Measures

Confirmed influenza A and B infection using a realtime

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.

Conclusion

Immunizing children and adolescents with inactivated influenza vaccine

significantly protected unimmunized residents of rural communities against influenza.

Trial Registration clinicaltrials.gov Identifier: NCT00877396

JAMA. 2010;303(10):943-950