Determinants of influenza vaccination, 2003-2004: shortages, fallacies and disparities

Abstract

Background: The influenza outbreak of 2003-2004 received substantial media attention, including widespread reports of a severe season and vaccine shortages. Understanding the determinants of vaccine receipt is important for guiding immunization policies.

Methods: From February through June 2004, we administered a structured telephone survey to Tennessee residents, using random-digit dialing methodology.

Results: Questionnaires were completed by 4028 persons, of whom 2077 (52%) had received influenza vaccination during the previous outbreak season. Of these 2077 vaccine recipients, 63% received vaccine at a private medical clinic, 14% at a workplace, 11% at a health department, and 7% at a pharmacy. Three-fourths of respondents reported a risk factor for which the Centers for Disease Control and Prevention recommends vaccination; of those, 41% went unvaccinated, including 26% who had seen a medical provider for other reasons during the influenza season. More than 40% of persons aged >or=50, more than half of health care workers, and 70% of pregnant women were not immunized. Blacks, rural residents, and lower-income respondents were significantly less likely to be immunized than were comparison groups. Of respondents who were vaccinated, 6% reported difficulties obtaining vaccination (most commonly, they reported that vaccine was not readily available). One-fourth of unvaccinated persons had been offered vaccination but had declined it; of these, 35% thought it unnecessary and 33% believed it would make them ill. Of those not vaccinated, 8% reported requesting vaccination but not receiving it, most commonly because it was unavailable.

Conclusions: Many barriers contribute to disparities in rates of influenza vaccination, of which inadequate supply is only one component. Myths regarding influenza vaccination persist tenaciously. A multifaceted approach to increasing immunization rates is critical.