Vaccines are just for kids, right? Not any more. U.S. health officials now recommend at least a half dozen vaccines for adults, to prevent pneumococcus virus, hepatitis, shingles and other ailments. And although the portion of adults who get these vaccinations rises slightly each year, the rates are still far too low to slow the spread of dangerous diseases throughout the general population.
Children receive a full slate of vaccinations at a young age, but the schedule for adults—which treatments to receive at which ages—is more complicated. The timing recommended by the U.S. Department of Health and Human Services and the U.S. Centers for Disease Control and Prevention (CDC) can be found at www.vaccines.gov. The CDC recently updated the nationwide vaccination rates that have been achieved for six major illnesses in the schedule. Modest gains have been achieved for Tdap (tetanus, diphtheria and acellular pertussis) and HPV (human papillomavirus), according to Carolyn Bridges, associate director of adult immunizations, but the number of adults who get those and other recommended vaccines remains very low.
In 2011 (the latest year for complete data) 13 percent of adults aged 19 to 64 received a Tdap shot, up from 9 percent in 2010. Although that progress is notable, the rate across a population needed to prevent the disease from spreading—known as the herd immunity threshold—is 85 percent for diphtheria and 92 percent for pertussis (whooping cough). Tetanus is not transmitted person to person, so there is no herd immunity rate. The CDC reported more than 9,300 adult cases of pertussis alone in 2012. The rate for children who receive Tdap is about 85 percent, but has fluctuated in recent years, and other childhood rates are slipping below herd immunity thresholds (see “The Danger of Opting Out”).
The rate for women who received one or more HPV vaccinations (three is recommended) between ages 19 and 26 (the target window) jumped to nearly 30 percent, up from 21 percent in 2010. Establishing a herd immunity level is a complex exercise for HPV, in part because it is transmitted sexually and not via the air, but a goal of about 80 percent is a tentative target. Improvement in vaccine coverage is also strongly recommended by the U.S. Department of Health and Human Services in a program called Healthy People 2020, which sets national objectives for enhancing the health of Americans.
Other adult rates also remain low, although a few bright spots exist. About half of all people who live to age 85 will develop shingles—a reactivation of the varicella-zoster virus (chicken pox) that hides in their bodies, often from childhood. Yet the share of adults age 60 or older that receive the vaccine is about 16 percent, according to Bridges. More encouraging is the so-called PPSV23 vaccine, which protects against streptococcus pneumoniae bacteria, also called pneumococcus. The infection causes severe sickness and death in thousands of adults each year, especially the elderly and those with compromised immune systems. Coverage among adults 65 and older has risen to a respectable 62 percent, perhaps on its way to the Healthy People 2020 goal of 90 percent. More than 4,000 Americans died from the bacteria in 2011, most over age 50.
High vaccination rates in adults are much harder to achieve than in children for several reasons. “There are no requirements, such as children having to have vaccinations before they are allowed to attend school,” notes William Schaffner, chair of preventive medicine at Vanderbilt University. Insurance programs may not cover certain vaccinations, require co-pays or demand that patients pay up front for later reimbursement—all obstacles, especially for the poor. Medicare does not cover all recommended vaccinations, either.
Even more of a barrier, Schaffner says, is a public health shortfall in informing people: “Most of the population thinks immunizations are for kids, other than maybe flu shots.” Together, poor education and payment hurdles “plague adult immunization rates,” he says. Still, he is encouraged by the slow but steady progress in at least certain adult vaccines such as Tdap.
Schaffner also notes that adults are benefitting from expanded children’s vaccination programs. In recent years new vaccines have been added to the list of recommendations for children, notably against pneumococcus, hepatitis A and rotavirus. The health community expected hepatitis A vaccinations in children to slow the spread of the illness to adults—and it has. The same has proved true for rotavirus. But results for pneumococcus have been the most dramatic. “We vaccinated kids because they have high rates of the virus, with lots of different strains," Schaffner explains. “The vaccine protects against seven strains. The rates plummeted in children, but to our surprise and enormous delight we discovered those same seven strains began to go down in adults, too.” Children carry the virus in their noses and throats and can readily pass it on to parents and grandparents, for example. “If kids are major distributors,” Schaffner concludes, “vaccinating them also protects the adults.”