Effects of Mass Media Coverage on Timing and Annual Receipt of Influenza Vaccination among Medicare Elderly

Influenza is associated with 36,000 deaths and 226,000 hospitalizations per year in the United States (Thompson et al. 2003, 2004). The elderly account for approximately 90 percent (33,000) of these deaths and 63 percent (142,000) of these hospitalizations (Thompson et al. 2003, 2004). Annual vaccination is the most effective strategy to reduce the morbidity from influenza (Centers for Disease Control and Prevention [CDC] 2007a). However, influenza vaccination levels among the noninstitutionalized elderly increased by only 2.4 percent from 1998 to 2002 (Lu et al. 2005), after reaching a “plateau” of about 70 percent during the late 1990s (CDC 2001a). New approaches may be needed to achieve the Healthy People 2010 goal of 90 percent vaccination coverage among the elderly population (CDC 2001a). Mass media is reported to substantially affect the knowledge of health and the use of health services (Grilli, Ramsay, and Minozzi 2002; Brodie et al. 2003;). For example, a celebrity campaign on colon cancer screening on NBC's Today's Show appeared to increase the colonoscopy rate by 38 percent during 9 months after the show (Cram et al. 2003). Influenza was ranked fourth among all health news stories followed by the American public during 1996–2002 (Brodie et al. 2003). However, only a limited number of studies (and no nationally representative studies) have attempted to quantify the effect of mass media on influenza vaccination. A long-term radio and television educational campaign was positively but weakly (p<.10) associated with an increase in the vaccination rate among West Virginia Medicare beneficiaries with diabetes (Schade and McCombs 2005). That study lacked a quantitative measure of media exposure and examined annual vaccination rate only, rather than assessing vaccination receipt closer in time to media exposure. Studies in Massachusetts (Gnanasekaran et al. 2006) and Colorado (Daley et al. 2006) have noted an indirect association between the annual vaccination rate in the pediatric population and media exposure. Neither study measured media exposure quantitatively. Another pediatric study quantified the media effect by counting the total number of media placements by week with either “influenza” or “flu” in the title (Ma et al. 2006). That study found a statistically significant relationship between weekly media coverage and weekly vaccination, but it did not control for other potential confounders (Ma et al. 2006). One factor that potentially contributes to delayed vaccination is vaccine supply shortage. Such shortages have occurred in four influenza seasons since 2000 (CDC 2000b, 2001b, 2007a). Lack of vaccine availability was the reason for nonvaccination according to 12.7 percent of unvaccinated Medicare beneficiaries aged 65 or older in 2000–2001, and 7.5 percent in 2001–2002 (CDC 2004). Vaccine supply not only affects the receipt of influenza vaccination but also the timing of vaccination. Vaccination earlier in the season is beneficial because of the 2-week lag before vaccination is fully effective (Kunzel et al. 1996; Chodick et al. 2006;) and because influenza disease outbreaks can occur as early as October, as observed in 2003 (CDC 2008b). In fact, supply shortage and delay led to the guideline changes in recommended timing for different populations, for example, vaccinating higher-risk populations earlier in the season than lower-risk populations (CDC 2000b, 2001b, 2007b). Also, some patients lose incentive to seek vaccination after a certain time in a season. A large number of vaccines delivered to clinics after November were unused in the 2000–2001 season (Iwane et al. 2007), even though an influenza epidemic could start in January and end in April as observed in 2002 (CDC 2008b). The purpose of our study was to measure the association between mass media coverage on flu-related topics and influenza vaccination regarding vaccination timing and annual vaccination rates among a nationally representative Medicare elderly population. Focusing on short time frames enabled us to distinguish, at the individual level, between media exposure before vaccination and unrelated media exposure after vaccination. It also enabled us to control for vaccine shortages at short intervals.