June 18, 2012 at 8:29 AM ET
An increasing number of parents may be choosing to delay or limit certain vaccinations for their young children, a new study shows, even as cases of pertussis, or whooping cough, continue to rise nationwide, with recent outbreaks in California and Washington.
The study, which examined medical records for 97,711 Portland children, found an almost four-fold increase between 2006 and 2009 in the percentage of parents who delayed or skipped vaccinations, researchers reported in the journal Pediatrics. Experts say that by delaying certain vaccinations, parents may be putting their children -- and those of others -- at a far greater risk of contracting deadly diseases, such as pneumonia and pertussis.
The new study examined the vaccination histories of children born in the Portland area between 2003 and 2009. Between 2006 and 2009, the number of parents who rejected government recommendations and made up their own vaccine schedules rose from 2.5 percent to 9.5 percent.
While the researchers could not say how typical the Portland results are compared to other areas around the country -- Portland schools reportedly have some of the highest vaccine exemption rates in the U.S. -- a 2011 study published in Pediatrics found that 13 percent of parents nationwide were using alternative schedules. Another study published in Public Health Report in 2010 found that almost 22 percent of parents were deviating in some way from the CDC's recommendations for infant vaccinations -- either by delaying shots, leaving out certain vaccines, or skipping vaccinations altogether.
The vaccine delays may not completely explain recent whooping cough outbreaks in states such as California and Washington, but “they certainly don’t help,” said Dr. Jaime Deville, a UCLA professor of infectious diseases in the pediatrics department.
The main reason parents give for delaying shots is fear their children will be harmed by receiving multiple vaccines at the same time, according to the study’s lead author, Steve Robison, an epidemiologist at the Oregon Health Authority. The vaccines most likely to be delayed by 9 months were for hepatitis B and pneumococcal disease (pneumonia).
For example, at both the two- and six-month visits the CDC recommends kids get a total of six vaccines. Even with some of them combined that adds up to a lot of shots. By age 4, children receive up to 28 vaccinations, based on the CDC immunization schedule.
Some parents believe they’ll get the same benefit if they spread the vaccinations out over more doctors’ visits rather than getting them all at once.
“There are rumors out there that your body can’t handle that many vaccines, that your body won’t be able to respond appropriately if you get several all at one time,” Robison said.
Experts say vaccines pose no harm to babies; even though multiple shots can be painful for a few moments, they say the consequences of delaying vaccinations can be much worse.
There are reasons for concern over the delayed vaccines. According to the Centers for Disease Control and Prevention there were 2,325 cases of pertussis in Washington state through June 9, 2012, compared to 171 during the same time period in 2011. A 2010 outbreak in California led to 9,143 cases -- including 10 infant deaths -- the most cases in that state since 1947.
"We’d like parents to know that the recommended number of doses of a vaccine is what is needed to build adequate protection levels both for their child and for the community," Robison said. "One dose of a vaccine, such as for pertussis, doesn’t build enough protection."
By 9 months, infants on an alternative vaccine schedule had fewer injections than those with parents following the government recommended schedule -- an average of 6.4 versus 10.4 shots -- and more doctors’ visits for vaccinations.
What’s more, few had caught up with the recommended number of vaccinations by the end of the study.
One big problem with the modified schedule is that parents are bringing children who haven’t been appropriately vaccinated into the doctor’s office more often -- thus putting other kids at greater risk, said pediatrician Dr. Andrew Nowalk, an assistant professor at the Children’s Hospital of Pittsburgh at the University of Pittsburgh Medical Center.
Deville is especially concerned about parents who are choosing to delay the pneumococcal vaccine until age 2. Infants are most vulnerable to pneumonia during the first year of life. "Parents who delay the vaccine until age 2 are leaving their children vulnerable during the period where it occurs at its highest frequency,” Deville said.
An added advantage of the pneumococcal vaccine is that it lowers the amount of bacteria living in kids’ noses and throats, Nowalk said. “So the children who aren’t getting vaccinated are more likely to be carrying the bacteria without being infected and spreading it to others,” he added. “When you don’t vaccinate your child you’re not only putting your child at risk but also those of others.”
Further, Nowalk said, there are lots of kids out there with immune deficiencies -- those with leukemia, or depressed immune systems because of organ transplants, for example -- who can't get vaccines. So they have to rely on everyone else getting vaccinated.
“When enough of the population is immunized, transmission is essentially stopped,” Deville explained. “The bottom line is that immunizations are extremely safe. They have the most value of any of our interventions when it comes to prolonging life and preventing diseases – not only for our own children but also for the community.”
Copyright 2013 Thomson Reuters.