Your toddler might be improperly vaccinated, even if she's had every immunization the government recommends, according to a new study from the Centers for Disease Control and Prevention.
More than one in four children are out of compliance with U.S. vaccination guidelines, say researchers led by Elizabeth Luman, Ph.D., of the National Center for Immunization and Respiratory Diseases.
The CDC researchers measured vaccine coverage for more than 17,000 2-year-old children against federal guidelines from the Advisory Committee on Immunization Practices (ACIP). The advisors make recommendations for routine childhood vaccinations based on safety and efficacy studies.
For 50 years, the U.S. government has counted missed vaccine doses to measure compliance, but that standard significantly underestimates the problem, according to the new research.
Government figures do not account for other vaccine lapses - like doses given at the wrong age or at wrong intervals. By factoring these in, the study found that compliance drops to only 72 percent - 9 percent lower than previously thought.
"We were surprised that accounting for other recommendations affected results so much," Luman said. She added that many lay people and health workers wrongly believe that the government bases estimates of vaccine coverage on all the ACIP guidelines.
The study appears in the June issue of the American Journal of Preventive Medicine. The CDC analysis relies on vaccination reports from families who participated in the 2005 National Immunization Survey, which randomly surveyed households with children, then followed up with their vaccine providers.
Missed doses account for two-thirds of vaccine lapses, according to the new estimate.
The study also revealed that some children get their shots too early. For instance, about 3 percent of children had their last hepatitis B vaccines prior to age 6 months, the minimum recommended for that immunization. Other toddlers received their first measles vaccine while their mother's antibodies still protected them, in effect wasting that dose.
Another lapse - getting serial doses too close together - affects 3 percent of children.
Outbreaks of vaccine-preventable disease have been in the news lately. Were missed doses or mis-timed doses an issue?
In these cases, the problem was children who had received no vaccinations whatsoever, said Jane Seward, deputy director of the Division of Viral Diseases in the National Center for Immunization and Respiratory Diseases.
"During recent measles outbreaks in San Diego, Arizona, and Wisconsin, all cases have occurred among individuals who had not received any measles vaccine," Seward said.
Reflecting the new study findings, "some of these measles cases represent missed opportunities in both children and adults," Seward said, while "the remaining cases occurred in infants too young to have been vaccinated or among children whose parents had chosen not to have their children vaccinated because of personal or religious beliefs."
The CDC researchers say they did not design the study to measure public health outcomes. "We didn't look at impact on disease; we were really focused on vaccination status of 2-year-olds," Luman said.
Denice Cora-Bramble, M.D., of the Children's National Medical Center, in Washington, D.C., deals with these issues in her work every day.
"I respect the general findings, but then we have to walk over to the clinical setting," she said. "If a kid comes in seven days too early, but the physician thinks they won't come back, do you send them home?" said Cora-Bramble, who was unaffiliated with the CDC research.
Luman acknowledges this real-life dilemma: "It's most important that kids get all the doses they're supposed to have," she said. "Providers sometimes have to do a balancing act: avoiding missed opportunities versus giving valid vaccinations. But for the 8 percent of children who received an invalid dose, official guidelines call for those vaccinations to be repeated."
Some of these children might need revaccination before they can start school, Luman said.
Cora-Bramble, who is executive director of the Goldberg Center for Community Pediatric Health, said the study covers new ground and is particularly relevant to her organization, which is working to improve its immunization rates through mobile health vans and other outreach and follow-up efforts.
"Vaccine compliance is an important benchmark for pediatricians," Cora-Bramble said. "These are some real issues that we struggle with as clinicians."
"I have two kids, and from a parent's point of view, it can be hard, logistically, to come in when scheduled," Luman said. "But I know how important timely vaccination is for the health of my children and my community."
American Journal of Preventive Medicine: Contact the editorial office at (858) 457-7292 or [email protected]
Luman ET, Shaw KM, Stokley SK. "Compliance with vaccination recommendations for U.S. children." Am J Prev Med 34(6), 2008.