Does mass media coverage on influenza increase disparities in influenza vaccine receipt among the Medicare elderly?

Research Objective: Persistent disparities in influenza vaccination rates have been reported in terms of racial/ethnic groups and socioeconomic status (SES) groups among the Medicare elderly. The literature suggests influenza vaccine receipt is positively associated with mass media coverage on influenza, which is assumed to increase risk perception and hence motivate vaccination. We tested hypotheses that associations between media coverage and vaccine receipt are different between subpopulations, i.e., positive and greater associations among white, higher income and higher educational-level subgroups among the Medicare elderly.

Methods: Cross-sectional multivariate survival analyses (using log-logistic models) during each of three influenza vaccination seasons between September 1999 and December 2001, using the 1999-2001 Medicare Current Beneficiary Survey (MCBS) (un-weighted N=7,462, 7,372, 7,462 and weighted N = 25 million, 24 million, and 24 million for 1999-2001, respectively). The outcome variable was daily vaccine receipt. We measured daily media coverage by counting the number of television program transcripts and newspaper/wire service articles, including keywords of influenza/flu and vaccine shortage/delay. All models controlled for three types of media, vaccine supply, influenza epidemic levels, and individual factors. Three types of interaction-terms were created between media variables and three subpopulations: white, income level of $20,000 or higher, and educational level of 13 years or more. One model included only one type of these interaction-terms.

Principal Findings: One article in nationwide newspapers increased daily vaccine receipt during subsequent weeks by 17%-42% (p<.05), and the sum of all reports by 4 major television networks increased this rate by 1%-27% (p<.05). This increase was different in magnitude across subpopulations as hypothesized. The magnitude of an association between nationwide newspapers' articles and the vaccine receipt was approximately 12%-48% (p<.05) greater among white Medicare beneficiaries, compared to other races. The magnitude of the same association between nationwide newspapers' articles and the vaccine receipt was approximately 7% (p<.05) greater among white Medicare beneficiaries with an income level of $20,000 or higher, compared to those with a lower income level. There was little difference in the association between the coverage of 4 major television networks and vaccine receipt across different racial groups, income levels and educational levels.

Conclusion: Receipt of influenza vaccination appears to be positively associated with media coverage. This association appears to be greater among white Medicare beneficiaries and those with higher income.