Trends in compliance with two-dose influenza vaccine recommendations in children aged 6 months through 8 years, 2010-2015

Background: Children aged 6 months through 8 years may require two doses of influenza vaccine for adequate immune response against the disease. However, poor two-dose compliance has been reported in the literature.

Methods: We analyzed data for >2.6million children from six immunization information system (IIS) sentinel sites, and assessed full vaccination coverage and two-dose compliance in the 2010-2015 influenza vaccination seasons. Full vaccination was defined as having received at least the recommended number of influenza vaccine doses (one or two), based on recommendations from the Advisory Committee on Immunization Practices. Two-dose compliance was defined as the percentage of children during each season who received at least two doses of influenza vaccine among those who required two doses and initiated the series.

Results: Across seasons, ⩾1-dose influenza vaccination coverage was mainly unchanged among 6-23montholds (range: 60.9-66.6%), 2-4yearolds (range: 44.8-47.4%), and 5-8yearolds (range: 34.5-38.9%). However, full vaccination coverage showed increasing trends from 2010-11 season to 2014-15 season (6-23months: 43.0-46.5%; 2-4yearolds: 26.3-39.7%; 5-8yearolds, 18.5-33.9%). Across seasons, two-dose compliance remained modest in children 6-23months (range: 63.3-67.6%) and very low in older children (range: 11.6-18.7% in children 2-4yearsand6.8-13.3% in children 5-8years). In the 2014-15 season, among children who required and received 2 doses, only half completed the two-dose series before influenza activity peaked.

Conclusions: Improved messaging of the two-dose influenza vaccine recommendations is needed for providers and parents. Providers are encouraged to determine a child's eligibility for two doses of influenza vaccine using the child's vaccination history, and to vaccinate children early in the season so that two-dose series are completed before influenza peaks.