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

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.

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

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.

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.