900. Effect of Influenza Vaccine Priming on Current Season Vaccine Effectiveness among Children and Adolescents, US Flu VE Network 2014–2015 Through 2017–2018

Background Studies have demonstrated that optimal protection against childhood influenza requires two “priming” doses of influenza vaccine in the first season of vaccination. Two doses of influenza vaccine are recommended for US children aged 6 months-8 years who received ≤1 dose in prior seasons. We examined risk of influenza among children fully or partially vaccinated during study seasons and vaccine effectiveness (VE) by the number of...