Implementing a recommendation that all Americans be vaccinated against influenza may dramatically reduce health care costs and the number of people infected with seasonal influenza in the United States.
These findings come from a study published on the website of Value in Health, the official journal of the International Society for Pharmacoeconomics and Outcomes Research (ISPOR).
Seasonal influenza is a contagious, airborne infection that kills more than 36,000 people each year in the United States and leads to approximately 200,000 hospitalizations. The illness is responsible for more than 600,000 life-years lost and direct medical costs in the range of $10 billion per year in the United States.
The research, conducted by OptumInsight Life Sciences, formerly Ingenix Life Sciences, and Chancellor Health Economics Ltd., found that with a universal vaccination policy, the number of people suffering from influenza-related illnesses each year might shrink by 2 million cases, saving $3 billion in associated health care and productivity costs. Universal vaccination may also save 34,000 quality-adjusted life years (QALYs). QALY is a unit of measure that combines life years gained as a result of health interventions/health care programs with a judgment about the quality of these life years.
"To our knowledge, this is the first economic evaluation that considers application of universal influenza vaccination in the United States," said Karen M. Clements, ScD, lead author of the study and project manager for OptumInsight Life Sciences. "Our analysis shows that there are significant clinical and economic benefits associated with a universal vaccination program, which supports the CDC's recent recommendation to expand influenza vaccination."
In February 2010, the Centers for Disease Control and Prevention's (CDC) Advisory Committee on Immunization Practices called for annual influenza vaccination to include all people in the United States aged six months and older, starting with the 2010-2011 influenza season. In prior years, vaccination was recommended for children up to the age of 18, but health authorities have expanded the target population, partly because people in the 19- to 49-year-old age bracket were hit hard by the 2009 H1N1 pandemic virus.
Methodology and Results
The base case analysis compared cost and infection rates as a result of universal vaccination to costs and infection rates under a targeted vaccination program for an average flu season. To perform the analysis, researchers first stratified the U.S. population by age, from under 5 to 65 and older. For each group, they estimated the likelihood of contracting influenza-like illness and complications, while estimating health care utilization, costs and survival rates.
Under each type of vaccination program, they estimated lifetime costs in 2008 U.S. dollars and QALYs lost. The time horizon for the vaccination program was one year, but the costs and QALYs from that vaccination program were assessed over the individual's lifetime. The researchers then used the results to derive incremental cost-effectiveness ratios.
Cost and outcome data used in the analyses were drawn from a variety of public sources, including published inpatient and outpatient health insurance claims, life expectancy data from the National Center for Health Statistics, care provider cost data from the 2008 Physicians Fee and Coding Guide, and published reports on the impact of the implementation of universal vaccination in Ontario, Canada, in 2000.
"While there was no precedent for universal vaccination against influenza in the United States, our study cites Ontario as the example," said David Thompson, Ph.D., senior vice president of health economics and strategic consulting for OptumInsight Life Sciences. "The result of that implementation was decreased flu-related mortality and reduced reliance on health care resources, compared with other provinces that had not adopted universal vaccination."
In the base case analysis, a total of 63 million people contracted influenza-related illnesses under a targeted vaccination program, compared with 61 million in a universal vaccination scenario. The targeted program resulted in 859,000 QALYs lost, vs. 825,000 QALYs lost in the universal vaccination program. And the total cost under the targeted scenario was $114 billion, compared with $111 billion under the universal program.
The researchers also developed five alternative scenarios dealing with eventualities such as one season's vaccine providing only weak protection. In addition, the researchers ran simulations on an effect known as herd immunity, in which unvaccinated individuals remain disease-free because many people they come into contact with have been vaccinated, and are therefore not carrying influenza infection.
Researchers constructed various models to address elements of uncertainty. Among them was the problem that there is no way to predict how many unvaccinated individuals in a given year will suffer from influenza-like illness. Nor is it possible to say how many people actually will get vaccinated under the universal recommendations. Establishing alternative models led the researchers to conclude that the program would yield significant cost savings and improvements in QALYs gained, even in a year in which relatively few people might be expected to fall ill.
Another alternative scenario showed that if actual vaccination coverage increased at a rate that was only one-half as great as occurred in Ontario after a universal program was implemented, this shortcoming would not nullify the anticipated cost savings.
To ensure that any errors in prediction would fall on the conservative side, the researchers opted not to include indirect effects of vaccination arising from herd immunity in the base case analysis, as including such effects would substantially increase the health benefits reflected in the model.