Biao Wang, Margaret L. Russell, Kevin Fonseca, David J. D. Earn, Fred Aoki, Gregory Horsman, Paul Van Caeseele, Khami Chokani, Mark Vooght, Lorne Babiuk, Stephen D. Walter, and Mark Loeb (2016)
Effect of Influenza Vaccination of Children on Infection Rate in Hutterite Communities: Follow-up Study of a Randomized Trial
PLoS One, 11(12):e0167281.
BACKGROUND
An earlier cluster randomized controlled trial (RCT) of Hutterite colonies had shown that if more than 80\% of children and adolescents were immunized with influenza vaccine there was a statistically significant reduction in laboratory-confirmed influenza among all unimmunized community members. We assessed the impact of this intervention for two additional influenza seasonal periods.
METHODS
Follow-up data for two influenza seasonal periods of a cluster randomized trial involving 1053 Canadian children and adolescents aged 36 months to 15 years in Season 2 and 1014 in Season 3 who received the study vaccine, and 2805 community members in Season 2 and 2840 in Season 3 who did not receive the study vaccine. Follow-up for Season 2 began November 18, 2009 and ended April 25, 2010 while Season 3 extended from December 6, 2010 and ended May 27, 2011. Children were randomly assigned in a blinded manner according to community membership to receive either inactivated trivalent influenza vaccine or hepatitis A. The primary outcome was confirmed influenza A and B infection using RT-PCR assay. Due to the outbreak of 2009 H1N1 pandemic, data in Season 2 were excluded for analysis.
RESULTS
For an analysis of the combined Season 1 and Season 3 data, among non-recipients (i.e., participants who did not receive study vaccines), 66 of the 2794 (2.4\%) participants in the influenza vaccine colonies and 121 of the 2301 (5.3\%) participants in the hepatitis A colonies had influenza confirmed by RT-PCR, for a protective effectiveness of 60\% (95\% CI, 6\% to 83\%; P = 0.04); among all study participants (i.e., including both those who received study vaccine and those who did not), 125 of the 3806 (3.3\%) in the influenza vaccine colonies and 239 of the 3243 (7.4\%) in the hepatitis A colonies had influenza confirmed by RT-PCR, for a protective effectiveness of 63\% (95\% CI, 5\% to 85\%; P = 0.04).
CONCLUSION
Immunizing children and adolescents with inactivated influenza vaccine can offer a protective effect among unimmunized community members for influenza A and B together when considered over multiple years of seasonal influenza.
An earlier cluster randomized controlled trial (RCT) of Hutterite colonies had shown that if more than 80\% of children and adolescents were immunized with influenza vaccine there was a statistically significant reduction in laboratory-confirmed influenza among all unimmunized community members. We assessed the impact of this intervention for two additional influenza seasonal periods.
METHODS
Follow-up data for two influenza seasonal periods of a cluster randomized trial involving 1053 Canadian children and adolescents aged 36 months to 15 years in Season 2 and 1014 in Season 3 who received the study vaccine, and 2805 community members in Season 2 and 2840 in Season 3 who did not receive the study vaccine. Follow-up for Season 2 began November 18, 2009 and ended April 25, 2010 while Season 3 extended from December 6, 2010 and ended May 27, 2011. Children were randomly assigned in a blinded manner according to community membership to receive either inactivated trivalent influenza vaccine or hepatitis A. The primary outcome was confirmed influenza A and B infection using RT-PCR assay. Due to the outbreak of 2009 H1N1 pandemic, data in Season 2 were excluded for analysis.
RESULTS
For an analysis of the combined Season 1 and Season 3 data, among non-recipients (i.e., participants who did not receive study vaccines), 66 of the 2794 (2.4\%) participants in the influenza vaccine colonies and 121 of the 2301 (5.3\%) participants in the hepatitis A colonies had influenza confirmed by RT-PCR, for a protective effectiveness of 60\% (95\% CI, 6\% to 83\%; P = 0.04); among all study participants (i.e., including both those who received study vaccine and those who did not), 125 of the 3806 (3.3\%) in the influenza vaccine colonies and 239 of the 3243 (7.4\%) in the hepatitis A colonies had influenza confirmed by RT-PCR, for a protective effectiveness of 63\% (95\% CI, 5\% to 85\%; P = 0.04).
CONCLUSION
Immunizing children and adolescents with inactivated influenza vaccine can offer a protective effect among unimmunized community members for influenza A and B together when considered over multiple years of seasonal influenza.
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