Subjective and objective risk as predictors of influenza vaccination during the vaccine shortage of 2004-2005

Background. We aimed to identify the role of objective risk status and subjective risk beliefs in influenza vaccination decisions during the recent rationing of influenza vaccine. Method. A random sample of 300 Americans, obtained through random-digit dialing, was interviewed regarding influenza vaccination practices and beliefs in September 2004 and again in March 2005. Results. One-half of individuals at high risk of influenza did not know that they were at high risk and, therefore, were not vaccinated. Respondents at high objective risk were more likely to report having been vaccinated than respondents who were not at high objective risk (36% vs. 6%, respectively; odds ratio, 8.31; 95% confidence interval, 3.65 - 18.88). However, a more powerful predictor of self-reported vaccination was subjective risk (64% vs. 7%, respectively; odds ratio, 24.02; 95% confidence interval, 12.18-48.09). Subjective risk fully mediated the relationship between objective risk and vaccination. Other predictors of vaccination included physician recommendation, habit, prior vaccination intention, belief that the influenza vaccine is safe and effective, perceived likelihood of getting influenza, and trait neuroticism. Conclusion. Health communication efforts must be more effective in persuading adults with chronic illness and individuals in contact with persons at risk that they should be vaccinated against influenza.