Perspectives in Disease Prevention and Health Promotion Influenza Vaccination Coverage Levels in Selected Sites -- United States, 1989
In 1988, the Congressionally mandated Influenza Vaccine Demonstration Project awarded demonstration grant funds for the 1988-89 and 1989-90 influenza seasons to nine geographic areas, including states and counties. Goals of this project were to determine 1) the cost-effectiveness of Medicare coverage of influenza vaccination and 2) whether Medicare reimbursement and other measures to enhance vaccine delivery result in increased influenza vaccination levels among Medicare Part B beneficiaries (i.e., persons aged greater than or equal to 65 years or persons of any age with a disability or who have end-stage renal disease). Each area includes an intervention site, where influenza vaccine is a benefit provided to these beneficiaries, and a comparison site, where the benefit is not provided. Intervention sites were chosen based on their ability to support promotional intervention efforts to increase vaccine coverage, and comparison sites were chosen on the basis of similar demographic and health service utilization characteristics. Annual surveys in the nine areas will assess changes in influenza vaccine coverage.
This report summarizes preliminary results of the first survey, conducted from May through July, 1989.* Because vaccine distribution was limited during the project's first year, the data reported here are considered baseline.
A telephone survey was conducted using the September 1988 update of the Medicare statistical data file to select a stratified probability sample of noninstitutionalized Medicare Part B beneficiaries from each demonstration site. The age-sex-race distribution of the sample at each intervention site was replicated for its comparison site. Telephone numbers were available for approximately 65% of selected beneficiaries. Respondents were asked about vaccination status for the 1987-88 and 1988-89 influenza seasons, source of influenza vaccination, presence of an underlying medical condition, and factors influencing influenza vaccination status (e.g., concern about side effects). Data from this survey are self-reported.
For each of the intervention and comparison sites, at least 940 respondents were surveyed. The 17,643 respondents represented a 60% completion rate. The overall influenza vaccination coverage estimate for noninstitutionalized Medicare beneficiaries for the 1987-88 influenza season was 41% (95% confidence interval (CI)=39.9-41.3), and for 1988-89, 43% (95% CI=42.7-44.1) (Table 1, page 165). Coverage in intervention sites tended to be slightly higher than coverage in comparison sites.
The lowest reported vaccination level was among persons aged less than or equal to 65 years with a disability or who had end-stage renal disease (30% (377/1259)). In comparison, among persons aged 65-75 years and greater than 75 years, coverage was 42% (4352/10,310) and 48% (2931/6074), respectively. Vaccination levels for males (44%) and females (43%) were similar; the level for races other than white (31%) was substantially lower than for whites (44%). Among persons with and without an underlying medical condition, vaccination levels were 48% and 39%, respectively.
Of 7660 persons vaccinated, 62% reported receiving vaccine from a private physician. Among the 9983 (57%) persons not vaccinated, at least 91% were candidates for vaccination based on recommendations of the Immunization Practices Advisory Committee (ACIP) (1). The most commonly (54%) cited reason for not being vaccinated was that persons considered themselves healthy and not in need of vaccination. Additional reasons cited included: concern about side effects (30%), concern about illness associated with the vaccine (30%), and lack of a physician's recommendation for vaccination (15%). Reported by: Div of Health Systems and Special Studies, Office of Research and Demonstrations, Health Care Financing Administration. Div of Immunization, Center for Prevention Svcs, CDC.
Editorial Note: The public health impact of epidemic influenza is dramatic: influenza accounted for greater than or equal to 10,000 excess deaths during each of 19 epidemics that occurred in the United States from 1957 to 1986 (1). In three of these epidemics, more than 40,000 excess deaths occurred. However, because influenza vaccine is up to 75% effective in preventing complications and death from influenza among high-risk older persons residing in institutions (2), much of this health burden is preventable.
Influenza vaccine is recommended annually for persons with chronic cardiopulmonary disorders; residents of nursing homes and other chronic-care facilities; healthy adults greater than or equal to 65 years of age; adults and children with metabolic diseases (including diabetes mellitus), renal dysfunction, hemoglobinopathies, or immunosuppression; children and teenagers receiving long-term aspirin therapy; health-care personnel caring for high-risk patients; and home-care and household contacts of high-risk persons. In addition, vaccination should be considered for persons with human immunodeficiency virus infection, travelers to countries where influenza is likely to occur, persons providing essential community services, students or other persons in institutional settings (e.g., schools and colleges), and persons who wish to reduce their risk of acquiring influenza infection (1,3,4).
Findings from this survey suggest that influenza vaccination coverage among older persons may be higher than documented in previous surveys. For example, the most recent national coverage estimate (from the 1985 U.S. Immunization Survey) for persons aged greater than or equal to 65 years was 23%. For 1987, the Behavioral Risk Factor Surveillance System estimated influenza vaccination coverage among persons aged greater than or equal to 65 years to be 32% (5); state-specific estimates ranged from 24% to 41%. Finally, in 1987, the number of doses of trivalent influenza vaccine distributed was greater than 24 million** (CDC, unpublished data), the highest number of doses distributed in any year since 1976.
The results of this study are based on nonrandomly selected sites and cannot be generalized to the entire U.S. population of noninstitutionalized persons greater than or equal to 65 years of age for at least two reasons. First, vaccination status of nonrespondents and the 35% of Medicare Part B beneficiaries for whom telephone numbers were not available could not be determined and could result in bias of unknown direction and magnitude. Second, sites that offered to participate in the project as intervention sites may have been more likely to have ongoing active adult immunization programs (6,7). Thus, vaccination levels in the survey areas may be higher than in other areas.
Because the project was implemented late in the 1988-89 influenza season, adequate data are not yet available to conduct a cost-effectiveness evaluation. The demonstration sites will be monitored for the success of intervention efforts in increasing influenza immunization levels. At the completion of the project, if Medicare coverage is determined to be cost effective, influenza vaccine will become a covered benefit for all Medicare Part B beneficiaries.
The high proportion of vaccinees reporting a private physician as their source of vaccination and the substantial group reporting lack of a physician's recommendation as a reason for not being vaccinated underscore the influence of health-care providers in the decision to be vaccinated (8,9). Educational and promotional campaigns may help dispel concerns among patients regarding the benefits, safety, and efficacy of influenza vaccine. Health-care providers should use every opportunity to assess patients' immunization status and recommend influenza vaccine and all other vaccines (hepatitis B, measles, mumps, rubella, and pneumococcal vaccines, and diphtheria and tetanus toxoids) appropriate for adults (1,3,4).
*A second survey will be conducted in the summer of 1990. The project is expected to continue for 1991 and 1992.
**Previous estimates of 27 million (5) were based on provisional data.
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