The Long-Term Evidence for VaccinesVaccination does more than protect against flu. Study after study shows that keeping children safe from viruses has long-lasting, positive health benefits.
Dec 7, 2009
With some reports saying that the worst of the H1N1 outbreak may have already come and gone this flu season in North America but not worldwide, parents who decided to sit out vaccinations for their children may feel validated. But not only is that strategy risky, it's uninformed, and ignores a larger truth about the benefit of vaccines. Throughout North America and Europe, an anti-vaccination movement has steadily grown over the past two decades, and was recently jet-propelled amid anxiety over immunizing pregnant women and children against the H1N1 "swine flu." The greatest fall-off in child vaccination, and the strongest proponents of various theoretical dangers associated with vaccines, are all rooted in wealthy, mostly Caucasian communities, located in the rich world. At a time when billions of people living in poorer countries are clamoring for equitable access to life-sparing drugs and vaccines for their families, the college-educated classes of the United States and other rich countries are saying "no thanks," even accusing their governments of "forcing" them to give "poison" to their children.
Will the children of these naysaying parents of the rich world turn to Mom and Dad 30 years from now and say, "Thanks for not getting me immunized. Thanks especially for saying no to the flu vaccine?"
If a woman is exposed to influenza while pregnant, or if an unvaccinated child gets the flu in his or her first year of life, the baby's developing brain may be severely damaged by the virus. Analysis of medical records of Americans who were born in the late '50s and early '60s shows that having the mother catch the flu while pregnant increased the chance her child would later develop schizophrenia. It's not a trivial difference: the children of moms who had flu midway during their pregnancies were as much as eight times more likely to become schizophrenic.
Overall, prenatal and infant exposure to influenza is strongly associated with cognitive failures. Babies are born with brains and immune systems that are still developing, and will not be hard-wired and strong until their second year of life. Scientists are increasingly discovering links between viral infections during those precious times, and psychiatric problems ranging from lifelong depression to acute learning deficits. In utero or infancy infection with chickenpox doubles the risk of cerebral palsy, according to Australian researchers. Having rubella during pregnancy increases by 80 percent the chances of severe birth defects in that mother's child, including small brains and hearts, blindness, deafness, and severe learning deficits.
Children who contract measles, chickenpox, or whooping cough can develop encephalitis or meningitis—infections of the central nervous system—which can cause epilepsy, brain damage, and death. Parents cannot protect their children's brains against everything, but the basic battery of vaccines can block the bulk of these viral insults. And the good news is that the still-developing immune system of babies and infants is ripe for the vaccine-induced programming that can confer decades—in some cases, lifelong—protection.
Other vaccine-preventable diseases—measles, rubella, mumps, chickenpox, and whooping cough—can damage the optic nerves and hearing of fetuses and newborns. The effect in these cases is immediate and obvious. In the pre-vaccine era in the United States, a thousand kids lost their hearing every year due to measles infection, five out of every 10,000 children who contracted mumps suffered permanent deafness, and 10 percent of child deafness was due to rubella (a.k.a. German measles).
And today, in countries with spotty child-immunization achievements—including the United Kingdom—viral infection in utero or in infancy accounts for 10 to 25 percent of child deafness.
Influenza in utero or in the first year of a child's life is a major cause of adult cardiovascular disease—heart attacks and strokes. People who suffered influenza during the Great Pandemic of 1918–19 were 20 percent more likely to develop heart disease as adults. To put that in perspective, having a "bad cholesterol count" of more than 240mg confers a 20 percent elevated risk of heart attacks, according to the American Heart Association.
Dr. Marietta Vázquez studied 350 mothers and infants from birth to 12 months of age who were hospitalized at Yale-New Haven Hospital over nine flu seasons (2000–2009). The babies of flu-vaccinated moms were larger, healthier, and, 85 percent of the time, fully protected against influenza. Similar findings have recently been reported out of Bangladesh, where the babies of vaccinated moms averaged a half pound larger than their unprotected peers and were less likely to be born prematurely.
The good news is that five decades of global child-vaccination programs have dramatically reduced infant and child mortality rates, and improved life expectancies in most of the world. In September, UNICEF reported that for the first time since WWII the number of children dying in the world annually fell below 10 million in 2008, largely due to child immunization. Vaccines, UNICEF says, are saving 2.5 million kids from dying every single year.
But outbreaks of vaccine-preventable diseases are surfacing wherever clusters of people either decline immunization, or are denied it by virtue of population poverty. The unimmunized few are a threat to all, as they may harbor viruses and pass them onto others whose vaccine-induced immunity is waning due to HIV, cancer, or simply the passing of time. Conversely, failing to be immunized in childhood renders young adults vulnerable to infectious diseases that they may not encounter until they go off to college or travel outside of their home regions.
A cursory search of outbreak reports over the last 13 months demonstrates that measles, mumps, diphtheria, whooping cough, polio, and typhoid fever are surfacing now in all sorts of settings, from jet planes to college dormitories, from Dutch religious sects to villages of Caribbean islands. Some of these outbreaks are tiny, involving no more than a cluster of individuals. But over the last year, several outbreaks have reached epidemic levels.
The United Kingdom has more such outbreaks than any other wealthy country, and that comes as no surprise as Dr. Andrew Wakefield—a key proponent of the theory that additives in vaccines cause autism—started his anti-immunization career in the U.K., in 1998 publishing now thoroughly refuted "evidence" of an autism link. Wakefield is now the subject of a hearing conducted by the U.K.'s General Medical Council for alleged medical misconduct. The discovery that he was secretly funded by personal-injury lawyers that sued vaccine makers has further fueled inquiries. Still, Wakefield's ideas continue to resonate in the UK, to the dismay of the country's pediatricians. Today, 20 percent of U.K. children enter primary school without having completed their full schedule of basic vaccinations— 40 percent, in some parts of the country—according to the Department of Health.
For those fighting disease on the global stage, the H1N1 pandemic has brought into stark relief a puzzling, difficult dichotomy. In the wealthy world, where individuals have the luxury of demanding 100 percent safety, the balance between individual and population rights has shifted so far toward individualism that it is nearly impossible for public-health authorities to persuade people to accept even one in 1 billion risks on behalf of society as a whole. (The exception is the U.S. armed forces, where duty to country includes an obligation to accept full vaccination.) But the very tools of protection that many individuals in the rich world are rejecting—especially the H1N1 vaccine—are completely unavailable to more than half the population of the world. Some 24 million children last year had no access to basic vaccines, says UNICEF, and at least 4 billion people cannot get flu vaccines right now.
For the poor and emerging-market countries, this inequity in access to life-sparing public-health tools is viewed as not only grossly unfair, but as a sign of the arrogant hypocrisy of the wealthy world. The rich countries demand that the planet's poor make sacrifices to slow down epidemics—such as slaying their chickens to stop bird flu, or losing tourist dollars by publicly acknowledging outbreaks within their borders—but offer little in return, including access to precious vaccines.
Yes, the proper adjective is "precious": miracles of science that, combined with smallpox immunization, saved more lives during the 20th century than were lost in all the wars, all the genocides, and all the epidemics of that hundred years. When a baby in an African village dies of measles, or a schoolchild in China succumbs to typhoid fever, none can question how precious that lost life was, or how vital a difference a vaccine could have made.
GARRETT is a Pulitzer Prizewinning writer and senior fellow for global health at the Council on Foreign Relations. MARCH is a doctoral candidate at the Mailman School of Public Health at Columbia University, specializing in life course, social, and psychiatric epidemiology.
Wednesday, December 9, 2009
The Long-Term Evidence for Vaccines | Print Article | Newsweek.com Prelude to backlash against backlash?