Influenza has been called “the last great plague of humankind” because it still poses a serious health threat to our nation and the world. If a naturally occurring variant of a bird flu virus acquired the ability to replicate in the trachea and nose of humans, it would cause a pandemic, with consequences as potentially devastating as the 1918 flu, which killed 50 million people. Because influenza viruses are found in birds and many mammalian species, it will not be possible, as it was for smallpox, to wipe influenza from the face of the earth. The only way to control it is through adequate immunization programs.
In the past, public health officials have focused on immunizing the elderly, who are at greatest risk for severe illness and death from influenza. Yet the most effective way to protect the elderly, and everyone else, is to target kids. Computer-modeling studies suggest that immunizing 20 percent of children in a community is more effective at protecting those older than 65 than immunizing 90 percent of the elderly. Another study suggests that immunizing 70 percent of schoolchildren may protect an entire community (including the elderly) from flu. Schools are virus exchange systems, and children are “super-spreaders”—they “shed” more of the virus for longer periods than adults.
Perhaps the best example of the effectiveness of childhood vaccination comes from Japan. The 1957 flu pandemic prompted the Japanese to start a school-located childhood vaccination program. For at least 10 years vaccination against influenza was mandatory for all children. Excess deaths from influenza and pneumonia, a common complication, fell by half. (Death from all causes dropped, suggesting that the illness is underdiagnosed.) The study showed that for every 420 schoolchildren immunized, one life was saved, predominantly among the elderly. Once the program ended, immunization rates fell, and death rates rose dramatically over the next few years.
Mandating flu immunization for children in schools is a nonstarter in the U.S. Still, it is possible to achieve high immunization rates through voluntary community programs centered on schools. In Alachua County, Florida, the home of the University of Florida, a school-located influenza vaccination program has been in full operation since 2009. Implemented as a coalition of schools, health departments and community advocates and with the expert advice of my colleagues Parker A. Small, Jr., and J. Glenn Morris, Jr., of the University of Florida, the program administers FluMist nasal spray, a live attenuated vaccine, free of charge to students, from pre-K to 12th grade, in public and private schools regardless of insurance status. Immunization rates of elementary students have reached 65 percent—enough to reduce the incidence of influenza in Alachua County during the past two flu seasons to nearly zero.
Such a program administered in schools across the country would raise the overall immunization level, protect our communities, and provide a basis for rapidly immunizing the U.S. population against the next pandemic strain or even against a bioterrorist attack. It would save lives and money. Seasonal flu kills 36,000 people every year in the U.S. and costs more than $10 billion. The average family of four loses about $100 in wages.
School-wide vaccinations would require a big conceptual change in immunization strategies, involving schools, communities, pediatricians and health departments. Who will fund and lead such an effort? Probably not the states, which are cutting back on public health. The federal government is grappling with rising health care costs. The health insurance industry, which stands to save billions each year in reimbursements, is the logical choice, but so far it has been unwilling to take the lead. Someone will have to.
SCIENTIFIC AMERICAN ONLINE
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This article was originally published with the title Target the Super-Spreaders.