One afternoon when I was young, my mother and I waited on a long line of other mothers and children in a large school gymnasium. When we reached the head of our line, my mother sat me on her lap, and a nurse gave me an injection and a green lollipop. It was 1954, and I was one of 1.8 million children to receive the new Salk vaccine against poliomyelitis (polio) that year. But the vaccine came too late for our neighbor, a boy I'll call Bobby, who'd contracted polio a year earlier. He had the paralytic form, which accounts for fewer than 1% of cases. Although many people recover completely, Bobby didn't. He would travel the neighborhood on crutches, his legs encased in heavy braces. His gait had its own rhythm: thump-swish-clunk, as he planted the crutches, swung his legs forward, landed, then began again.
Before the Salk vaccine existed, some 13,000 to 20,000 cases of paralytic polio were reported annually in the United States. After its introduction, incidence declined rapidly; the last U.S. outbreak occurred in 1979. Since then, polio has been considered eradicated in this country. Although isolated cases occur, these are usually imported by travelers exposed outside U.S. borders. (We reported on one such case in 2006, that of an American college student who was traveling in Central America. She'd never been immunized because her parents objected on religious grounds, and she contracted paralytic polio from an infant who'd received the live vaccine.)
This month, most parents will be ushering their children to NPs and pediatricians to get back-to-school immunizations. But a significant number of children won't be immunized—some, because of medical contraindications (such as allergies or compromised immune systems); others, because their parents have religious or philosophical objections; and some, because their parents have concerns about vaccine safety. While national vaccination rates are generally high (at or near 90% for most vaccines), the sizable numbers of unvaccinated or undervaccinated children mean that several serious diseases remain a threat.
Measles is a case in point. By 2000, vaccination campaigns had essentially eradicated measles in this country. Yet in 2008, measles began reappearing across the nation. By July, 131 cases had been reported to the Centers for Disease Control and Prevention, the highest year-to-date number since 1996. Most of these cases were not imported but rather were "importation-associated"; that is, after the virus was brought in by travelers, it was spread further by nonimmunized people, and some of them became infected. Many were "school-aged children who were eligible for vaccination but whose parents chose not to have them vaccinated."
We're also seeing a resurgence of pertussis (see Emerging Infections, June). National incidence rates have risen markedly since the mid-1990s. Last year, California had one of its worst outbreaks, with 418% more cases reported during the first six months than during the same period in 2009. Missing, delayed, and waning immunity are believed to be factors.
Public health and infectious disease professionals are concerned about the outbreaks of vaccine-preventable diseases. In March, the Pediatric Infectious Diseases Society released a strongly worded position statement that says, in part, "Whether or not children should be vaccinated before childcare or school entry ought not be a matter of 'belief.' Rather, it should be a matter of public policy based on the best available scientific evidence, and in this case the science is definitive: vaccines are safe and they save lives. In this context, it is wrong to allow parents to exempt their children from required immunizations based on their personal beliefs."
In June, Health Affairs published results of a study on parental attitudes and behaviors concerning vaccination. The researchers found that a majority of parents surveyed said they trusted the vaccination advice of their children's health care providers. That's powerful evidence of our influence over those under our care and, in the long run, over public health outcomes. We must ensure that parents understand the ramifications of not vaccinating their children. It's not just their own children who might suffer the consequences.