In this study, persons with heart disease were more likely to be vaccinated than were persons within the same age group without any reported condition associated with increased risk of influenza complications. Moreover, we found that the likelihood of influen-za vaccination among persons with heart disease increased substantially with age. Nevertheless, vaccination coverage for persons with heart disease is below the national target level, particularly for adults aged 18 to 49 years. Vaccine coverage in this age group has remained stable during the past 5 years, with a slight decrease in 2000–2001 in all groups that has been attributed to delays in vaccine manufacturing and distribution. 15
Missed opportunities for vaccination may be frequent, since substantial proportions of persons who visit doctors frequently are unvaccinated.
Low vaccination coverage is attributed to a combination of factors: lack of systematic offering of vaccine to patients by physicians or providers at patient visits during the vaccination season; lack of awareness or interest in vaccination on the part of patients; and concerns and fears of patients regarding the influenza vaccine. Among persons aged 18 to 64 years with high-risk conditions who responded to a mail survey in 2001 (Healthstyles©
), the most commonly reported reasons for not being vaccinated were 1) not being offered vaccine by their provider or not knowing it was needed (40%), 2) concern about side effects (22%), and 3) believing that the shot doesn't work (22%).*
(Respondents could provide more than 1 reason.)
Systematic offering of vaccine by providers may be more difficult when the indications for vaccine are health conditions rather than age. Influenza vaccination is recommended for all persons aged 50 to 64 years, because 1) about one third of persons in this age group have a high-risk condition, 2) an age-based approach may be more effective in improving coverage in those at higher risk, and 3) 50- to 64-year-olds who are at lower risk can benefit from vaccination. 10
Interventions such as standing orders or provider reminders are necessary to ensure high vaccination rates; however, implementation of such interventions is infrequent. 16
Many persons with cardiac conditions see subspecialists, and subspecialists are less likely to recommend influenza vaccination than are generalists. 16
Recently published standards for the immunization of adults recommend that both primary care healthcare professionals and specialists should include routinely recommended vaccinations as part of their care. 17
We found that influenza vaccination coverage among persons with heart disease was significantly lower for blacks and Hispanics compared with whites, although the differences were not statistically significant for persons aged 18 to 49 years. Racial and ethnic disparities in influenza vaccination have been documented consistently, and these disparities persist after controlling for such factors as demographics, access to care, and utilization of care. 18,19
For Hispanics, English fluency appears to explain much of the difference; 18
however, the reasons for these disparities between blacks and whites are poorly understood. Survey findings suggest that among persons who were not vaccinated, reasons for non-vaccination were similar for blacks and whites. 20
The persistence of this disparity among persons who frequently encounter the healthcare system suggests that access to care is not a central factor explaining the disparity. Overall, we found much lower vaccination coverage for persons without health insurance, without a usual place of care, or with few recent doctor visits, indicating the importance of access to care, particularly among younger persons.
All data used in this analysis were from self-reports without validation. In addition, the specific influenza season during which the vaccination was reportedly received could not be exactly determined. The validity of self-reported influenza vaccination is considered high. 21
The validity of self-reported diabetes and hypertension is considered moderate. 21
To our knowledge, the validity of self-reported heart disease from NHIS respondents has not been evaluated.
Persons with heart disease are at increased risk of hospitalization or death resulting from influenza infection, and the benefits of influenza vaccine in preventing serious complications of influenza infection are well documented. A substantial proportion of high-risk persons aged 18 to 64 are not aware that they should be vaccinated, which highlights the importance of systematic offering of influenza vaccination by physicians. Primary care providers and cardiologists should work together to ensure that secondary prevention measures such as influenza and pneumococcal vaccination are offered to their patients with heart disease. Although changing patients' attitudes and beliefs about influenza vaccination and increasing the demand for vaccination is important, provider recommendation remains a very strong predictor of vaccination. 22