Evaluating the impact of influenza vaccination. A North American perspective

Recent studies in the US and Canada have shown that influenza vaccination prevents approximately 30 to 50% of all pneumonia and influenza hospitalisations and deaths that occur among elderly persons during 3-month influenza outbreak periods. These population-based studies have used retrospective methods and large computerised administrative databases. In addition, earlier cost-effectiveness studies have been supplemented by recent research from prepaid health plans showing that influenza vaccination can be cost saving. The use of influenza vaccine increased in the US and Canada throughout the 1980s and early 1990s, despite different methods for providing reimbursement for vaccination. The North American experience regarding the clinical effectiveness, cost effectiveness and epidemiology of influenza vaccination may provide European scientists and health officials with useful although sometimes limited insight into their own efforts to understand and improve influenza vaccination.

The effectiveness of vaccination against influenza in healthy, working adults

BACKGROUND

Although influenza causes substantial morbidity and mortality in all age groups, current recommendations emphasize annual immunization for people at high risk for complications of influenza. We conducted a double-blind, placebo-controlled trial of vaccination against influenza in healthy, working adults.

METHODS

In the fall of 1994, we recruited working adults from 18 to 64 years of age from in and around the Minneapolis-St. Paul area and randomly assigned them to receive either influenza vaccine or placebo injections. The primary study outcomes included upper respiratory illnesses, absenteeism from work because of upper respiratory illnesses, and visits to physicians' offices for upper respiratory illnesses. The economic benefits of vaccination were analyzed by estimating the direct and indirect costs associated with immunization and with upper respiratory illnesses.

RESULTS

We enrolled a total of 849 subjects. Baseline characteristics were similar in the two groups. During the follow-up period, consisting of the 1994-1995 influenza season (December 1, 1994, through March 31, 1995), those who received the vaccine reported 25 percent fewer episodes of upper respiratory illness than those who received the placebo (105 vs. 140 episodes per 100 subjects, P < 0.001), 43 percent fewer days of sick leave from work due to upper respiratory illness (70 vs. 122 days per 100 subjects, P = 0.001), and 44 percent fewer visits to physicians' offices for upper respiratory illnesses (31 vs. 55 visits per 100 subjects, P = 0.004). The cost savings were estimated to be $46.85 per person vaccinated.

CONCLUSIONS

Vaccination against influenza has substantial health-related and economic benefits for healthy, working adults.

The efficacy of influenza vaccine in elderly persons. A meta-analysis and review of the literature

OBJECTIVE

To quantify the protective efficacy of influenza vaccine in elderly persons.

DATA SOURCES

A MEDLINE search was done using the index terms influenza vaccine, vaccine efficacy, elderly, mortality, hospitalized, and pneumonia. Appropriate references in the initially selected articles were also reviewed.

STUDY SELECTION

Only cohort observational studies with mortality assessment were included in the meta-analysis. In addition, 3 recent case-control studies, 2 cost-effectiveness studies, and 1 randomized, double-blind, placebo-controlled trial were reviewed.

DATA EXTRACTION

Vaccine and epidemic virus strains, age and sex of patients, severity of illness, patient status, and study design were recorded. Upper respiratory illness, hospitalization, pneumonia, and mortality were used as outcome measures.

DATA SYNTHESIS

In a meta-analysis of 20 cohort studies, the pooled estimates of vaccine efficacy (1-odds ratio) were 56% (95% Cl, 39% to 68%) for preventing respiratory illness, 53% (Cl, 35% to 66%) for preventing pneumonia, 50% (Cl, 28% to 65%) for preventing hospitalization, and 68% (Cl, 56% to 76%) for preventing death. Vaccine efficacy in the case-control studies ranged from 32% to 45% for preventing hospitalization for pneumonia, from 31% to 65% for preventing hospital deaths from pneumonia and influenza, from 43% to 50% for preventing hospital deaths from all respiratory conditions, and from 27% to 30% for preventing deaths from all causes. The randomized, double-blind, placebo-controlled trial showed a 50% or greater reduction in influenza-related illness. Recent cost-effectiveness studies confirm the efficacy of influenza vaccine in reducing influenza-related morbidity and mortality and show that vaccine provides important cost savings per year per vaccinated person.

CONCLUSION

Despite the paucity of randomized trials, many studies confirm that influenza vaccine reduces the risks for pneumonia, hospitalization, and death in elderly persons during an influenza epidemic if the vaccine strain is identical or similar to the epidemic strain. Influenza immunization is an indispensable part of the care of persons 65 years of age and older. Annual vaccine administration requires the attention of all physicians and public health organizations.

Influenza and pneumococcal vaccination and tuberculin skin testing programs in long-term care facilities: where do we stand?

OBJECTIVE

1) To compare policies and procedures for distribution of influenza and pneumococcal vaccines to long-term care facilities for the elderly in Canada, 2) to determine vaccination rates of residents and staff, and 3) to describe vaccination and tuberculin skin testing programs in these facilities.

DESIGN

A cross-sectional survey consisting of telephone interviews and a mailed questionnaire was conducted in the spring of 1991. Telephone interviews were conducted with provincial/territorial epidemiologists. The questionnaire was sent to all (N = 1.520) Canadian long-term care facilities for the elderly with > or = 25 beds.

RESULTS

There were 1,270 responding facilities (84%). The mean overall influenza vaccination rate for residents was 78.5%. The mean vaccination rate was higher in those provinces in which the vaccine was paid for by the government (79% versus 71%; P = 0.002). Only 19% of facilities reported staff vaccination rates > 25%; rates again were higher in those provinces in which vaccine for staff was provided by the government. Pneumococcal vaccine was offered to residents in 12% of the facilities. The proportions of facilities with > 10% and > 75% of residents vaccinated were significantly higher in the provinces where the pneumococcal vaccine was recommended and paid for as compared with those where it was not (P < 0.001 for both). Tuberculin skin testing programs for residents existed in 360 long-term care facilities (28%) across the country.

CONCLUSION

In 1990, the number of residents living in Canadian long-term care facilities who were vaccinated against influenza and Streptococcus pneumoniae was suboptimal. Staff influenza vaccination rates were very low across the country. Most facilities did not have a baseline tuberculin skin test status for their residents. Vaccination rates are higher in jurisdictions in which governments provide the vaccine without charge.

Influenza vaccination programs for elderly persons: cost-effectiveness in a health maintenance organization

OBJECTIVE

To estimate the cost-effectiveness and net medical care costs of programs for annual influenza vaccinations for the elderly in a health maintenance organization (HMO).

DESIGN

Population-based, case-control study.

SETTING

The Northwest Region of Kaiser Permanente, a prepaid group practice HMO in Portland, Oregon.

PARTICIPANTS

Kaiser Permanente members 65 years of age and older who had at least 1 month of HMO eligibility during any of nine influenza seasons in the 1980s.

MEASUREMENTS

The HMO's costs for providing medical care and conducting vaccination programs were estimated using accounting data.

RESULTS

32% of high-risk elderly persons and 22% of non-high-risk elderly persons received influenza vaccinations. Aggregate vaccine effectiveness in preventing pneumonia and influenza hospitalizations was 30% (95% CI, 17% to 42%) for high-risk and 40% (CI, 1% to 64%) for non-high-risk elderly persons. The net savings to the HMO per vaccination was $6.11 for high-risk elderly persons and $1.10 for all elderly persons. The HMO incurred a net cost of $4.82 per vaccination for non-high-risk elderly persons.

CONCLUSIONS

Influenza vaccination rates in this HMO were relatively low for high-risk elderly persons. The medical care costs saved by preventing pneumonia and influenza through vaccination of high-risk elderly persons provide a compelling rationale to increase compliance with recommendations for annual influenza vaccination. Indirect benefits, such as prevention of suffering, incapacity, and lost wages, are likely to compensate for the small net cost of vaccinating non-high-risk elderly persons.

Implementation of the Medicare influenza vaccination benefit--United States, 1993

Influenza is a major cause of debilitating illness and premature death in the United States, particularly among persons aged > or = 65 years and those with chronic conditions such as lung or heart disease, diabetes, and cancer. Medicare reimbursement for excess hospitalizations during influenza epidemics ranges from $750 million to $1 billion (1). In May 1993, influenza vaccination became a covered Medicare benefit after its potential cost-effectiveness was established by the Medicare Influenza Vaccine Demonstration (2). During the fall of 1993, the Health Care Financing Administration (HCFA) initiated an information campaign to promote use of the influenza vaccination benefit, implemented simplified billing procedures, and improved electronic billing capabilities. However, reports during the 1993-94 influenza season suggested problems experienced by state and local health departments in implementing the new benefit. To characterize public influenza vaccination programs and problems with implementing this benefit, in the spring of 1994, CDC collected information from all 63 state and local health departments receiving federal immunization grants. This report summarizes the reports from these programs.

Influenza and pneumococcal vaccination of the elderly: newer vaccines and prospects for clinical benefits at the margin

The continued importance of pneumonia and influenza as a cause of hospitalization and death in the United States provides ample evidence of the need for more effective means of prevention. Recent reports have greatly enhanced our understanding of the impact of these infections as major contributions to the morbidity and mortality of respiratory disease. Other reports have provided new evidence of the clinical effectiveness of current influenza and pneumococcal vaccines and the cost effectiveness of vaccination. Together with studies on long-term outcomes of pneumonia patients, it is now clear that vaccination rather than pneumonia is truly "the old man's friend." These recent developments raise the question of what clinical benefits might be expected from new and improved influenza and pneumococcal vaccines. In all likelihood their marginal benefits will be small, and greater benefits might be achieved by overcoming problems in vaccine delivery and improving the implementation of public policies for vaccination.

Pandemic planning in Canada

A Canadian plan for pandemic influenza was completed by the National Advisory Committee on Immunization in 1988. Its development took several years and involved consultation with provincial public health and laboratory authorities, the licensing body, manufacturers of influenza vaccine and antiviral agents, and representatives in the USA and UK. Key decisions in creating the pandemic plan include: (1) aiming for federal-provincial consensus on use of vaccine and antiviral drugs, (2) a selective vaccination approach (high-risk persons plus essential workers), (3) bulk purchasing and distribution of vaccine through the public sector, (4) leaving antiviral drugs on the open market, (5) careful planning of the communications strategy, and (6) increasing inter-pandemic use of flu vaccine in target groups. The plan addresses recognition of a pandemic; activation of a Pandemic Influenza Committee whose membership and responsibilities are spelled out; the federal-provincial decision making process; influenza vaccine considerations; amantadine and other antiviral agents; estimates of target group size, vaccine uptake, manufacturing capabilities and time frames; and communication considerations. Since 1988, influenza vaccine use has increased considerably in Canada and experience has been gained with amantadine. Manufacturing capability within Canada for influenza vaccine has also been enhanced. It is now time to update the plan, especially the targets, and to make sure that everyone involved remains aware of the assigned roles.

Impact of Medicare reimbursement on influenza vaccination rates in the elderly

BACKGROUND

Influenza is responsible for significant morbidity, mortality, and medical costs, but immunization rates in the elderly remain low.

METHODS

As part of a demonstration project in rural Pennsylvania, 1,989 community-dwelling Medicare beneficiaries, 65-79 years old, completed a health risk appraisal including questions about flu shots. Participants were randomized to two experimental (hospital or physician) or control groups. Experimental groups were offered free flu shots for the 1990-91 flu season. Follow-up interviews to determine vaccination rates were completed about 1 year later.

RESULTS

Baseline immunization rates were almost identical for the hospital-based (41.2%), physician-based (41.3%), and control group not offered free immunizations (40.6%). Follow-up rates for the groups offered immunizations rose significantly to 63.6 and 69.1% for hospital and physician groups, respectively, while the control group also increased significantly to 54.1%. Individuals who were more educated, were older, and had greater chronic diseases history (myocardial infarction, hypertension, and pulmonary disease) were more likely to be immunized. Male and married elderly were more likely to be immunized as a result of the demonstration.

CONCLUSIONS

Increasing community education and providing immunizations free through Medicare will increase immunization rates among elderly. The elderly are more likely to receive flu shots provided through physicians' offices than through hospital-based clinics.

[Influenza: incidence and costs of inpatient treatment]

In Austria, in 1990, a total of 3,808 patients with influenza were hospitalized for treatment (49.34/100,000). The age-specific incidence rates show three peaks: < 5 years (132.05/100,000), adolescents (15 to 19-year-olds, 111.5/100,000), old-age groups (85-year-olds, 102.7/100,000). Complications occurred in 1,479 (38.8%) patients, including 846 cases (57.2%) with "other complications" of the respiratory tract, 365 cases (24.7%) of pneumonia, and 268 cases (18.1%) with manifestations affecting other organs. The 3.808 patients spent a total of 34,684 days in hospital. The overall costs of hospital treatment were some 104 million Austrian schillings (approx. 15 million German marks)--per patient on average 26,700 schillings (approx. 3,840 marks); per pneumonia patient 61,200 schillings (approx. 8,743 marks).

Final results: Medicare influenza vaccine demonstration--selected states, 1988-1992

Pneumonia and influenza (P&I) are the sixth leading cause of death in the United States, and persons aged > or = 65 years and persons with chronic conditions (e.g., lung or heart disease, diabetes, or cancer) are at greatest risk for P&I. During major epidemics, hospitalization rates for persons at highest risk may increase twofold to fivefold. However, only 30% of persons aged > or = 65 years responding to CDC's National Health Interview Survey for 1989 reported having received the influenza vaccine during the previous year. In 1988, the Health Care Financing Administration (HCFA) and CDC began a congressionally mandated 4-year demonstration project to evaluate the cost-effectiveness to Medicare of providing influenza vaccine to Medicare beneficiaries. This report presents final results of the Medicare Influenza Vaccine Demonstration conducted during 1988-1992.

Flu vaccinations: are they worth the cost?

Flu immunisation programmes have been offered by many organisations this year and companies will be expecting to see the dividend of reduced absenteeism. But are nonselective vaccinations worth the expense? Helen Kogan weighs up the arguments.

Review of cost-benefit analyses of influenza vaccine

Vaccination is an underutilised, low cost and effective method of preventing illness. Cost-effectiveness analysis discloses a beneficial role of influenza vaccination in preventing illness especially in patients over 65 years of age and in high risk patients. In one large study, when 150 million doses of influenza vaccine were given between 1971 and 1977 in the US, over 13 million more years of life were gained at a cost of only $US63 per year of life gained (1978 dollars). The vaccination programmes also resulted in productivity gains of approximately 5 million days which was valued at $US250 million. Other studies from Canada, Finland and the US found similar benefits. The findings of these studies are reviewed. In order to increase the use of influenza immunisation substantially, there has to be a greater acceptance of the value of immunisation by healthcare providers and the public.