Influenza Vaccine

Flu Vaccine Is 60% Effective During Most Flu Seasons

Influenza vaccination is safe and effective for preventing influenza hospitalizations in young children during most seasons, according to a recent study.

Over the course of 4 influenza seasons between 2010 and 2014, the researchers assessed the effectiveness of the influenza vaccine in 9982 children age 6 to 59 months who had been hospitalized for laboratory-confirmed influenza in Canada.

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For their study, the researchers calculated vaccine effectiveness estimates based on vaccination status (full vs partial), age, and influenza season. Results were adjusted for age, season, and time within season. Vaccine effectiveness incorporating prior history of influenza vaccination was also assessed.

Results indicated that, of 9982 patients, 12.8% had tested positive for influenza. The researchers found that vaccine effectiveness varied based on vaccination status, age, and influenza season. For vaccination status, vaccine effectiveness was 60% for full vaccination and 39% for partial vaccination across all 4 seasons combined.

For age group, vaccine effectiveness for full vaccination was 67% in children ages 24 to 59 months and 48% in children ages 6 to 23 months. For influenza season, vaccine effectiveness for full vaccination was 77% for the 2010-2011 season, 59% for the 2011-2012 season, 33% for the 2012-2013 season, and 72% for the 2013-2014 season.

The researchers noted that vaccine effectiveness in children ages 24 to 59 months appeared similar between those who had been vaccinated during the current and previous seasons and in those who had been vaccinated during the current season only. The only exception was in the 2012-2013 season, when vaccine effectiveness was lower for patients vaccinated during the current season only.

“Influenza vaccination is effective in preventing pediatric laboratory-confirmed influenza hospitalizations during most seasons,” the researchers concluded.

—Christina Vogt


Buchan SA, Chung H, Campitelli MA, et al. Vaccine effectiveness against laboratory-confirmed influenza hospitalizations among young children during the 2010-11 to 2013-14 influenza seasons in Ontario, Canada [Published online November 17, 2017]. PLoS One.