Scientists say practice has no proven value, poses risks

By Nathan Seppa

Web edition: June 20, 2012
Print edition: February 23, 2013; Vol.183 #4 (p. 11)

Parents in Oregon are increasingly delaying their children’s standard immunizations, a new study finds. The practice, which runs counter to medical advice, creates gaps in protection and increases the risk that a child won’t complete multishot vaccination regimens, researchers report in the July Pediatrics.

“There is really no benefit in altering the vaccination schedule beyond what the CDC recommends,” says Amanda Dempsey, a physician and researcher at the University of Colorado Denver, referring to the Centers for Disease Control and Prevention guidelines that babies get multiple vaccinations at ages 2, 4 and 6 months. “But there is a risk in prolonging the time that the child in question is at risk for contracting a preventable disease,” says Dempsey, who wasn’t part of this study.

Parental concerns about babies getting multiple shots per visit might stem in part from the increase in the number of routine vaccinations for infants since 1995, says study coauthor Steve Robison, an epidemiologist at the Oregon Health Authority in Portland. Vaccines now given in the first 6 months protect against hepatitis B, diphtheria, tetanus, whooping cough, meningitis, pneumonia, polio and flu.

But the growing resistance also coincides with publication of false claims linking vaccines to autism or other problems. And a handful of doctors have promoted delayed vaccine schedules that would require more visits in the first year and limit the shots administered at each.

Robison and his colleagues analyzed a medical database of nearly 100,000 children born in the Portland area from 2003 to 2009. In the first several years of that span, less than 4 percent of 9-month-olds didn’t get their vaccinations on schedule, and about one-fifth overall had at least one vaccination delayed. This trend rose from 2007 through 2009, when nearly 10 percent of kids didn’t get their vaccinations on time, with 30 percent overall experiencing some delays.

Portland is probably not unique, says Dempsey, who has studied vaccination delays. “I think this is very generalizable” to the rest of the country, she says.

The CDC website notes that stretching out vaccines typically doesn’t “reduce final antibody concentrations,” meaning full protection can still be reached. But CDC adds that “protection might not be attained until the recommended number of doses has been administered,” leaving a gap in protection.

Robison says parents who delay kids’ vaccinations might also lose track of whether a child has received a third or fourth shot in a series and risk having the child never complete the regimen.

The new study didn’t assess whether putting off immunizations led to more illness, but the trend in delaying or skipping vaccination has coincided with recent outbreaks of measles (SN: 11/19/11, p. 13) and whooping cough. CDC reported 27,550 cases of whooping cough, also known as pertussis, in 2010 in the United States. That included 9,143 cases in California — the most there in 63 years — and 10 infant deaths.

“There is pretty clear documentation in measles outbreaks that the main people at risk are unvaccinated or undervaccinated for that disease,” Dempsey says. Full measles immunization calls for two shots several years apart. “It’s not really too much of a leap of logic to say that when you delay scheduling or don’t follow the recommendations, you fall into that risk group.”