Influenza Vaccine Effectiveness Against Pediatric Deaths: 2010-2014

BACKGROUND AND OBJECTIVE: Surveillance for laboratory-confirmed influenza-associated pediatric deaths since 2004 has shown that most deaths occur in unvaccinated children. We assessed whether influenza vaccination reduced the risk of influenza-associated death in children and adolescents. METHODS; We conducted a case-cohort analysis comparing vaccination uptake among laboratory-confirmed influenza-associated pediatric deaths with estimated vaccination coverage among pediatric cohorts in the United States. Case vaccination and high-risk status were determined by case investigation. Influenza vaccination coverage estimates were obtained from national survey data or a national insurance claims database. We estimated odds ratios from logistic regression comparing odds of vaccination among cases with odds of vaccination in comparison cohorts. We used Bayesian methods to compute 95% credible intervals (CIs) for vaccine effectiveness (VE), calculated as (1 - odds ratio) x 100. RESULTS: From July 2010 through June 2014, 358 laboratory-confirmed influenza-associated pediatric deaths were reported among children aged 6 months through 17 years. Vaccination status was determined for 291 deaths; 75 (26%) received vaccine before illness onset. Average vaccination coverage in survey cohorts was 48%. Overall VE against death was 65% (95% CI, 54% to 74%). Among 153 deaths in children with underlying high-risk medical conditions, 47 (31%) were vaccinated. VE among children with high-risk conditions was 51% (95% CI, 31% to 67%), compared with 65% (95% CI, 47% to 78%) among children without high-risk conditions. CONCLUSIONS: Influenza vaccination was associated with reduced risk of laboratory-confirmed influenza-associated pediatric death. Increasing influenza vaccination could prevent influenza-associated deaths among children and adolescents.