Jeffrey C. Kwong
Immunization against influenza is effective in averting lab-confirmed influenza hospitalizations due to increased vaccine efficacy, according to a study published in PLoS ONE.
“Although most influenza infections are mild, influenza can cause ear infections, pneumonia and exacerbations of medical conditions, such as asthma. Some children experience complications, leading to hospitalization, admission to intensive care and even death,” Sarah Buchan, PhD, from the Dalla Lana School of Public Health, University of Toronto, Toronto, Ontario, Canada, told Infectious Diseases in Children. “Children who are unvaccinated are at greater risk of influenza infection, and therefore at greater risk of these serious outcomes than those who are vaccinated.”
To assess the efficacy of vaccination against lab-confirmed, influenza-related hospitalizations in children between 6 and 59 months of age, the researchers implemented a test-negative design that included children located in Ontario, Canada, who were hospitalized in the 2010-2011 to 2013-2014 influenza seasons.
Jeffrey C. Kwong, MD, MSc, CCFP, FRCPC, from the Dalla Lana School of Public Health, and colleagues then calculated vaccine efficacy estimates using logistic regression models adjusted for age, season and time within season when hospitalization occurred. Additionally, the researchers examined vaccine efficacy through the assessment of prior vaccination history against influenza.
Of the 9,982 patients included in the study, influenza was detected in 12.8% of specimens collected over four influenza seasons. Vaccine efficacy was observed at 60% for the four seasons combined for full vaccination (95% CI, 44%-72%) and 39% for partial vaccination (95% CI, 17%-56%). For children between the ages of 24 and 59 months, the researchers observed that full vaccination had an efficacy of 67% (95% CI, 48%-79%). In children aged 6 to 23 months, the vaccine was 48% effective (95% CI, 12%-69%).
For individual influenza seasons, the researchers observed a vaccine efficacy of 77% for 2010-2011 (95% CI, 47%-90%), 59% for 2011-2012 (95% CI, 12%-81%), 33% for 2012-2013 (95% CI, –18% to 62%) and 72% for 2013-2014 (95% CI, 42%-86%).
“Physicians who encounter vaccine hesitancy regarding influenza vaccination should counsel parents that young children — like older adults — experience higher rates of serious influenza-related outcomes than the general population,” Kwong told Infectious Diseases in Children. “Now, we have solid evidence that influenza vaccination reduces the risk of hospitalization for these children during most influenza seasons.” by Katherine Bortz
Disclosures: Buchan reports no relevant financial disclosures. Please see the full study for a list of the other authors’ relevant financial disclosures.