WASHINGTON, D.C. - "Infectious diseases do not respect national or regional borders; therefore, the United States has a self interest in being involved not only in the control and elimination of these vaccine-preventable diseases in this country ... but also elsewhere around the globe," said Stephen L. Cochi, MD, PhD, at a recent conference on the value of vaccines, hosted by the National Health Council and the Children's Vaccine Initiative.
Approximately 97 million passengers travel by air to and from the United States each year through approximately 50 U.S. international airports. In addition, over 150 other legal U.S. entry points also exist.
"So, the United States does have some vulnerability to importations, even after eliminating indigenous circulation of disease," said Cochi, acting deputy director, National Immunization Program, Centers for Disease Control and Prevention.
Smallpox was eradicated in 1977 and represents the best example of U.S. involvement in a worldwide campaign to eradicate a disease. This success offered humanitarian and economic benefits to the United States. The United States invested about $32 million in the program during 1966-1977. It is estimated that in the last 20 years, the total U.S. investment has been returned every 26 days.
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Cochi named measles elimination as another success. Indigenous circulation has been halted several times and currently all U.S. cases of measles are suspected to be a result of importation. However, despite the availability of a successful vaccine for over 30 years, 1 million deaths a year still occur worldwide in children younger than 5 years. Approximately 80% worldwide coverage with measles vaccine has been achieved, which is a "sign that our work is not finished," he said.
The major sources of importation of measles into the United States are the industrialized countries of western Europe and Asia, primarily Japan, Cochi said.
"We still need to apply effective vaccine intervention to eliminate the remaining disease burden," he added.
The United States currently spends $45 million a year simply to include the measles antigen in the measles-mumps-rubella (MMR) vaccine, excluding program and administration costs.
The U.S. measles elimination strategy is to achieve a high level of population immunity by providing the first dose of measles vaccine at 12-15 months of age and the second dose at school entry. The plan also involves enhancing the surveillance for measles, responding quickly to disease outbreaks and improving global control of measles.
"We've come very close to eliminating indigenous measles from the United States, but we will never be successful in doing so unless we achieve global elimination of measles," said Cochi.
The United States has record-low levels of measles cases. Only about 125 cases were reported as of early December 1997, a 75% reduction from last year, Cochi said. Much of the success is due to a region-wide effort of North and South America which began in 1994. In 1996, just over 2,000 cases of measles were reported in the Western Hemisphere.
The challenges to domestic measles elimination include continual importation of measles, assurance of on-time high vaccination coverage among preschool age children, the second dose for all school children and assurance of high quality surveillance.
International challenges include the mobilization of political commitment in industrialized countries (Germany, Italy, Japan and France) and inadequate financial support to pursue this initiative.
The United States also plays a major part in the polio eradication effort. The last case of wild polio in the United States was in 1979 and the last case in the Western Hemisphere occurred in 1991.
"We have to continue to immunize against polio to keep up a barrier against manifestations of the disease until global polio eradication occurs," said Cochi, who is also chief of the NIP's Polio Eradication Activity.
Dramatic potential savings exist from polio eradication. The United States currently spends $230 million a year on polio vaccine and $1.7 billion is spent globally.
A global polio laboratory network, consisting of more than 80 laboratories, was established by the World Health Organization to study poliovirus and also serves as a surveillance network. The network consists of specialized and regional reference laboratories, and national laboratories around the world.
Globally, infectious diseases are still a major cause of mortality. Infectious diseases, some of them preventable, account for 17 million of the 52 million - approximately one-third - total deaths each year.
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