Surveillance of influenza vaccination coverage--United States, 2007-08 through 2011-12 influenza seasons

Abstract

Problem/condition: Substantial improvement in annual influenza vaccination of recommended groups is needed to reduce the health effects of influenza and reach Healthy People 2020 targets. No single data source provides season-specific estimates of influenza vaccination coverage and related information on place of influenza vaccination and concerns related to influenza and influenza vaccination.

Reporting period: 2007-08 through 2011-12 influenza seasons.

Description of systems: CDC uses multiple data sources to obtain estimates of vaccination coverage and related data that can guide program and policy decisions to improve coverage. These data sources include the National Health Interview Survey (NHIS), the Behavioral Risk Factor Surveillance System (BRFSS), the National Flu Survey (NFS), the National Immunization Survey (NIS), the Immunization Information Systems (IIS) eight sentinel sites, Internet panel surveys of health-care personnel and pregnant women, and the Pregnancy Risk Assessment and Monitoring System (PRAMS).

Results: National influenza vaccination coverage among children aged 6 months-17 years increased from 31.1% during 2007-08 to 56.7% during the 2011-12 influenza season as measured by NHIS. Vaccination coverage among children aged 6 months-17 years varied by state as measured by NIS. Changes from season to season differed as measured by NIS and NHIS. According to IIS sentinel site data, full vaccination (having either one or two seasonal influenza vaccinations, as recommended by the Advisory Committee on Immunization Practices for each influenza season, based on the child's influenza vaccination history) with up to two recommended doses for the 2011-12 season was 27.1% among children aged 6 months-8 years and was 44.3% for the youngest children (aged 6-23 months). Influenza vaccination coverage among adults aged ≥18 years increased from 33.0% during 2007-08 to 38.3% during the 2011-12 influenza season as measured by NHIS. Vaccination coverage by age group for the 2011-12 season as measured by BRFSS was <5 percentage points different from NHIS estimates, whereas NFS estimates were 6-8 percentage points higher than BRFSS estimates. Vaccination coverage among persons aged ≥18 years varied by state as measured by BRFSS. For adults aged ≥18 years, a doctor's office was the most common place for receipt of influenza vaccination (38.4%, BRFSS; 32.5%, NFS) followed by a pharmacy (20.1%, BRFSS; 19.7%, NFS). Overall, 66.9% of health-care personnel (HCP) reported having been vaccinated during the 2011-12 season, as measured by an Internet panel survey of HCP, compared with 62.4%, as estimated through NHIS. Vaccination coverage among pregnant women was 47.0%, as measured by an Internet panel survey of women pregnant during the influenza season, and 43.0%, as measured by BRFSS during the 2011-12 influenza season. Overall, as measured by NFS, 86.8% of adults aged ≥18 years rated the influenza vaccine as very or somewhat effective, and 46.5% of adults aged ≥18 years believed their risk for getting sick with influenza if unvaccinated was high or somewhat high.

Interpretation: During the 2011-12 season, influenza vaccination coverage varied by state, age group, and selected populations (e.g., HCP and pregnant women), with coverage estimates well below the Healthy People 2020 goal of 70% for children aged 6 months-17 years, 70% for adults aged ≥18 years, and 90% for HCP.

Public health actions: Continued efforts are needed to encourage health-care providers to offer influenza vaccination and to promote public health education efforts among various populations to improve vaccination coverage. Ongoing surveillance to obtain coverage estimates and information regarding other issues related to influenza vaccination (e.g., knowledge, attitudes, and beliefs) is needed to guide program and policy improvements to reduce morbidity and mortality associated with influenza by increasing vaccination rates. Ongoing comparisons of telephone and Internet panel surveys with in-person surveys such as NHIS are needed for appropriate interpretation of data and resulting public health actions. Examination of results from all data sources is necessary to fully assess the various components of influenza vaccination coverage among different populations in the United States.